{"id":30176,"date":"2026-07-17T12:53:00","date_gmt":"2026-07-17T04:53:00","guid":{"rendered":"https:\/\/www.cnspd.com\/?p=30176"},"modified":"2026-07-17T16:42:27","modified_gmt":"2026-07-17T08:42:27","slug":"24v-signal-surge-protector-selection-guide-for-sensors-and-plc-i-o","status":"publish","type":"post","link":"https:\/\/www.cnspd.com\/pt\/24v-signal-surge-protector\/","title":{"rendered":"24V Signal Surge Protector Selection Guide for Sensors and PLC I\/O"},"content":{"rendered":"\t\t<div data-elementor-type=\"wp-post\" data-elementor-id=\"30176\" class=\"elementor elementor-30176\" data-elementor-post-type=\"post\">\n\t\t\t\t<div class=\"elementor-element elementor-element-0dcc869 e-flex e-con-boxed e-con e-parent\" data-id=\"0dcc869\" data-element_type=\"container\" data-e-type=\"container\">\n\t\t\t\t\t<div class=\"e-con-inner\">\n\t\t\t\t<div class=\"elementor-element elementor-element-201bc42 elementor-widget elementor-widget-html\" data-id=\"201bc42\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"html.default\">\n\t\t\t\t<div class=\"elementor-widget-container\">\n\t\t\t\t\t<style>\r\n  .ly24v-page,\r\n  .ly24v-page * {\r\n    box-sizing: border-box;\r\n  }\r\n\r\n  .ly24v-page {\r\n    --ly24v-primary: #004898;\r\n    --ly24v-primary-dark: #00366f;\r\n    --ly24v-primary-light: #0c5cad;\r\n    --ly24v-primary-soft: #edf5fd;\r\n    --ly24v-ink: #172033;\r\n    --ly24v-text: #455269;\r\n    --ly24v-muted: #6c788c;\r\n    --ly24v-line: #d9e3ee;\r\n    --ly24v-line-dark: #c6d4e2;\r\n    --ly24v-bg: #f6f8fb;\r\n    --ly24v-white: #ffffff;\r\n    --ly24v-green: #21794e;\r\n    --ly24v-green-bg: #eaf7f0;\r\n    --ly24v-yellow: #84580b;\r\n    --ly24v-yellow-bg: #fff1cf;\r\n    --ly24v-red: #bd4741;\r\n    --ly24v-red-bg: #fff2f1;\r\n    --ly24v-shadow: 0 12px 34px rgba(21, 44, 75, 0.075);\r\n\r\n    container: ly24v \/ inline-size;\r\n\r\n    width: 100%;\r\n    max-width: 1180px;\r\n    margin: 0 auto;\r\n    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999px;\r\n    background: var(--ly24v-primary);\r\n  }\r\n\r\n  .ly24v-section-head {\r\n    max-width: 870px;\r\n    margin-bottom: 28px;\r\n  }\r\n\r\n  .ly24v-section-head > p {\r\n    margin-bottom: 0;\r\n    color: var(--ly24v-muted);\r\n    font-size: 18px;\r\n  }\r\n\r\n  \/* =========================================================\r\n     INTRO\r\n  ========================================================= *\/\r\n\r\n  .ly24v-intro {\r\n    padding: 38px;\r\n    border: 1px solid var(--ly24v-line);\r\n    border-radius: 22px;\r\n    background:\r\n      linear-gradient(\r\n        135deg,\r\n        rgba(0, 72, 152, 0.06),\r\n        rgba(255, 255, 255, 0) 58%\r\n      ),\r\n      var(--ly24v-white);\r\n    box-shadow: var(--ly24v-shadow);\r\n  }\r\n\r\n  .ly24v-intro h2 {\r\n    max-width: 900px;\r\n    margin-bottom: 15px;\r\n    font-size: 39px;\r\n  }\r\n\r\n  .ly24v-lead {\r\n    max-width: 940px;\r\n    margin-bottom: 25px !important;\r\n    font-size: 20px;\r\n    line-height: 1.63;\r\n  }\r\n\r\n  .ly24v-tags {\r\n    display: flex;\r\n    flex-wrap: wrap;\r\n    gap: 9px;\r\n    margin-bottom: 27px;\r\n  }\r\n\r\n  .ly24v-tag {\r\n    display: inline-flex;\r\n    align-items: center;\r\n    min-height: 34px;\r\n    padding: 6px 12px;\r\n    border: 1px solid #c5d9ef;\r\n    border-radius: 999px;\r\n    background: var(--ly24v-primary-soft);\r\n    color: var(--ly24v-primary-dark);\r\n    font-size: 13px;\r\n    font-weight: 750;\r\n    line-height: 1.3;\r\n    white-space: normal;\r\n  }\r\n\r\n  .ly24v-direct-answer {\r\n    padding: 25px 27px 26px;\r\n    border: 1px solid #c9dcf1;\r\n    border-left: 5px solid var(--ly24v-primary);\r\n    border-radius: 15px;\r\n    background: var(--ly24v-primary-soft);\r\n  }\r\n\r\n  .ly24v-direct-label {\r\n    display: inline-flex;\r\n    align-items: center;\r\n    min-height: 30px;\r\n    margin-bottom: 12px;\r\n    padding: 5px 11px;\r\n    border-radius: 999px;\r\n    background: #dcecff;\r\n    color: var(--ly24v-primary-dark);\r\n    font-size: 12px;\r\n    font-weight: 850;\r\n    line-height: 1.2;\r\n    letter-spacing: 0.065em;\r\n    text-transform: uppercase;\r\n  }\r\n\r\n  .ly24v-direct-answer p {\r\n    max-width: 920px;\r\n    margin: 0;\r\n    color: var(--ly24v-ink);\r\n    font-size: 17px;\r\n    font-weight: 520;\r\n    line-height: 1.68;\r\n  }\r\n\r\n  .ly24v-scope {\r\n    display: grid;\r\n    grid-template-columns: repeat(2, minmax(0, 1fr));\r\n    gap: 16px;\r\n    margin-top: 23px;\r\n  }\r\n\r\n  .ly24v-scope-card {\r\n    min-width: 0;\r\n    padding: 18px 19px;\r\n    border: 1px solid var(--ly24v-line);\r\n    border-radius: 13px;\r\n    background: var(--ly24v-white);\r\n  }\r\n\r\n  .ly24v-scope-card strong {\r\n    display: block;\r\n    margin-bottom: 6px;\r\n    color: var(--ly24v-ink);\r\n  }\r\n\r\n  .ly24v-scope-card p {\r\n    margin: 0;\r\n    font-size: 14px;\r\n    line-height: 1.55;\r\n  }\r\n\r\n  .ly24v-scope-card.is-in {\r\n    border-top: 4px solid var(--ly24v-primary);\r\n  }\r\n\r\n  .ly24v-scope-card.is-out {\r\n    border-top: 4px solid #99a8ba;\r\n  }\r\n\r\n  \/* =========================================================\r\n     TABLE OF CONTENTS\r\n  ========================================================= *\/\r\n\r\n  .ly24v-toc {\r\n    margin-top: 29px;\r\n    padding: 24px 27px;\r\n    border: 1px solid var(--ly24v-line);\r\n    border-radius: 17px;\r\n    background: var(--ly24v-bg);\r\n  }\r\n\r\n  .ly24v-toc-title {\r\n    margin-bottom: 13px;\r\n    color: var(--ly24v-ink);\r\n    font-size: 18px;\r\n    font-weight: 850;\r\n  }\r\n\r\n  .ly24v-toc ol {\r\n    display: grid;\r\n    grid-template-columns: repeat(2, minmax(0, 1fr));\r\n    gap: 8px 32px;\r\n    padding-left: 20px;\r\n  }\r\n\r\n  .ly24v-toc li {\r\n    margin: 0;\r\n    color: var(--ly24v-primary);\r\n    font-size: 15px;\r\n  }\r\n\r\n  .ly24v-toc a {\r\n    text-decoration: none;\r\n  }\r\n\r\n  .ly24v-toc a:hover {\r\n    text-decoration: underline;\r\n  }\r\n\r\n  \/* =========================================================\r\n     QUICK SELECTION\r\n  ========================================================= *\/\r\n\r\n  .ly24v-selection-grid {\r\n    display: grid;\r\n    grid-template-columns: repeat(3, minmax(0, 1fr));\r\n    gap: 17px;\r\n  }\r\n\r\n  .ly24v-selection-card {\r\n    display: flex;\r\n    flex-direction: column;\r\n    min-width: 0;\r\n    min-height: 100%;\r\n    padding: 23px;\r\n    border: 1px solid var(--ly24v-line);\r\n    border-top: 4px solid var(--ly24v-primary);\r\n    border-radius: 16px;\r\n    background: var(--ly24v-white);\r\n    box-shadow: 0 7px 22px rgba(22, 46, 80, 0.045);\r\n  }\r\n\r\n  .ly24v-selection-card-head {\r\n    min-width: 0;\r\n    margin-bottom: 17px;\r\n    padding-bottom: 16px;\r\n    border-bottom: 1px solid var(--ly24v-line);\r\n  }\r\n\r\n  .ly24v-selection-type {\r\n    display: block;\r\n    margin-bottom: 7px;\r\n    color: var(--ly24v-ink);\r\n    font-size: 19px;\r\n    font-weight: 850;\r\n    line-height: 1.32;\r\n  }\r\n\r\n  .ly24v-selection-device {\r\n    display: block;\r\n    color: var(--ly24v-muted);\r\n    font-size: 13.5px;\r\n    line-height: 1.52;\r\n  }\r\n\r\n  .ly24v-selection-body {\r\n    display: flex;\r\n    flex: 1 1 auto;\r\n    flex-direction: column;\r\n    min-width: 0;\r\n  }\r\n\r\n  .ly24v-selection-label {\r\n    display: block;\r\n    margin-bottom: 7px;\r\n    color: var(--ly24v-primary);\r\n    font-size: 11px;\r\n    font-weight: 900;\r\n    line-height: 1.3;\r\n    letter-spacing: 0.065em;\r\n    text-transform: uppercase;\r\n  }\r\n\r\n  .ly24v-selection-body p {\r\n    flex: 1 1 auto;\r\n    margin: 0 0 17px;\r\n    color: var(--ly24v-text);\r\n    font-size: 14px;\r\n    line-height: 1.57;\r\n  }\r\n\r\n  .ly24v-selection-status {\r\n    display: inline-flex;\r\n    align-items: center;\r\n    align-self: flex-start;\r\n    max-width: 100%;\r\n    min-height: 30px;\r\n    padding: 6px 10px;\r\n    border-radius: 9px;\r\n    font-size: 12px;\r\n    font-weight: 850;\r\n    line-height: 1.3;\r\n    white-space: normal;\r\n  }\r\n\r\n  .ly24v-selection-status.is-confirm {\r\n    background: var(--ly24v-yellow-bg);\r\n    color: var(--ly24v-yellow);\r\n  }\r\n\r\n  .ly24v-selection-status.is-product {\r\n    background: var(--ly24v-green-bg);\r\n    color: var(--ly24v-green);\r\n  }\r\n\r\n  .ly24v-selection-status.is-separate {\r\n    background: #edf1f6;\r\n    color: #4c596b;\r\n  }\r\n\r\n  .ly24v-answer-strip {\r\n    margin-top: 18px;\r\n    padding: 18px 20px;\r\n    border: 1px solid #b9d2ec;\r\n    border-radius: 13px;\r\n    background: var(--ly24v-primary-soft);\r\n  }\r\n\r\n  .ly24v-answer-strip strong {\r\n    display: block;\r\n    margin-bottom: 5px;\r\n    color: var(--ly24v-ink);\r\n  }\r\n\r\n  .ly24v-answer-strip p {\r\n    margin: 0;\r\n  }\r\n\r\n  \/* =========================================================\r\n     TABLES\r\n  ========================================================= *\/\r\n\r\n  .ly24v-table-wrap {\r\n    position: relative;\r\n    width: 100%;\r\n    max-height: 640px;\r\n    overflow: auto;\r\n    border: 1px solid var(--ly24v-line-dark);\r\n    border-radius: 16px;\r\n    background: var(--ly24v-white);\r\n    box-shadow: 0 6px 20px rgba(25, 48, 79, 0.045);\r\n    scrollbar-gutter: stable;\r\n    -webkit-overflow-scrolling: touch;\r\n  }\r\n\r\n  .ly24v-table {\r\n    width: 100%;\r\n    min-width: 820px;\r\n    margin: 0;\r\n    border-collapse: separate;\r\n    border-spacing: 0;\r\n    table-layout: auto;\r\n    color: var(--ly24v-text);\r\n    font-size: 15px;\r\n    line-height: 1.52;\r\n  }\r\n\r\n  .ly24v-table th,\r\n  .ly24v-table td {\r\n    padding: 16px 17px;\r\n    border-right: 1px solid var(--ly24v-line);\r\n    border-bottom: 1px solid var(--ly24v-line);\r\n    text-align: left;\r\n    vertical-align: top;\r\n    overflow-wrap: normal;\r\n    word-break: normal;\r\n    hyphens: none;\r\n  }\r\n\r\n  .ly24v-table thead th {\r\n    position: sticky;\r\n    top: 0;\r\n    z-index: 5;\r\n    background: var(--ly24v-primary);\r\n    color: var(--ly24v-white);\r\n    font-size: 14px;\r\n    font-weight: 850;\r\n    line-height: 1.35;\r\n    box-shadow: 0 1px 0 var(--ly24v-primary);\r\n  }\r\n\r\n  .ly24v-table th:first-child,\r\n  .ly24v-table td:first-child {\r\n    width: 150px;\r\n    min-width: 150px;\r\n  }\r\n\r\n  .ly24v-table th:nth-child(2),\r\n  .ly24v-table td:nth-child(2) {\r\n    min-width: 210px;\r\n  }\r\n\r\n  .ly24v-table th:last-child,\r\n  .ly24v-table td:last-child {\r\n    border-right: 0;\r\n  }\r\n\r\n  .ly24v-table tbody tr:last-child td {\r\n    border-bottom: 0;\r\n  }\r\n\r\n  .ly24v-table tbody tr:nth-child(even) td {\r\n    background: #f8fafc;\r\n  }\r\n\r\n  .ly24v-table strong {\r\n    color: var(--ly24v-ink);\r\n  }\r\n\r\n  .ly24v-table small {\r\n    display: block;\r\n    margin-top: 4px;\r\n    color: var(--ly24v-muted);\r\n    font-size: 12px;\r\n    line-height: 1.4;\r\n  }\r\n\r\n  \/* =========================================================\r\n     RISK CARDS\r\n  ========================================================= *\/\r\n\r\n  .ly24v-card-grid {\r\n    display: grid;\r\n    grid-template-columns: repeat(4, minmax(0, 1fr));\r\n    gap: 15px;\r\n  }\r\n\r\n  .ly24v-card {\r\n    min-width: 0;\r\n    padding: 22px;\r\n    border: 1px solid var(--ly24v-line);\r\n    border-radius: 15px;\r\n    background: var(--ly24v-white);\r\n    box-shadow: 0 7px 22px rgba(27, 51, 83, 0.04);\r\n  }\r\n\r\n  .ly24v-card-icon {\r\n    display: inline-grid;\r\n    place-items: center;\r\n    width: 35px;\r\n    height: 35px;\r\n    margin-bottom: 14px;\r\n    border-radius: 10px;\r\n    background: var(--ly24v-primary);\r\n    color: var(--ly24v-white);\r\n    font-size: 14px;\r\n    font-weight: 900;\r\n  }\r\n\r\n  .ly24v-card h3 {\r\n    margin-bottom: 8px;\r\n    font-size: 19px;\r\n  }\r\n\r\n  .ly24v-card p {\r\n    margin: 0;\r\n    font-size: 14px;\r\n    line-height: 1.55;\r\n  }\r\n\r\n  \/* =========================================================\r\n     FIGURES\r\n  ========================================================= *\/\r\n\r\n  .ly24v-figure {\r\n    width: 100%;\r\n    margin: 29px 0;\r\n    padding: 9px;\r\n    border: 1px solid var(--ly24v-line);\r\n    border-radius: 18px;\r\n    background: var(--ly24v-white);\r\n    box-shadow: 0 10px 30px rgba(22, 46, 80, 0.07);\r\n    overflow: hidden;\r\n  }\r\n\r\n  .ly24v-figure img {\r\n    width: 100%;\r\n    aspect-ratio: 16 \/ 9;\r\n    border-radius: 12px;\r\n    background: #f4f7fb;\r\n    object-fit: contain;\r\n  }\r\n\r\n  .ly24v-figure figcaption {\r\n    padding: 12px 8px 4px;\r\n    color: var(--ly24v-muted);\r\n    font-size: 14px;\r\n    line-height: 1.55;\r\n    text-align: center;\r\n  }\r\n\r\n  \/* =========================================================\r\n     NOTES\r\n  ========================================================= *\/\r\n\r\n  .ly24v-note,\r\n  .ly24v-warning,\r\n  .ly24v-success {\r\n    margin-top: 23px;\r\n    padding: 20px 22px;\r\n    border-radius: 14px;\r\n  }\r\n\r\n  .ly24v-note {\r\n    border: 1px solid #bcd3ec;\r\n    background: var(--ly24v-primary-soft);\r\n  }\r\n\r\n  .ly24v-warning {\r\n    border: 1px solid #ebc66f;\r\n    background: #fff7e5;\r\n  }\r\n\r\n  .ly24v-success {\r\n    border: 1px solid #94c9ac;\r\n    background: #eef8f3;\r\n  }\r\n\r\n  .ly24v-note strong,\r\n  .ly24v-warning strong,\r\n  .ly24v-success strong {\r\n    display: block;\r\n    margin-bottom: 6px;\r\n    color: var(--ly24v-ink);\r\n  }\r\n\r\n  .ly24v-note p:last-child,\r\n  .ly24v-warning p:last-child,\r\n  .ly24v-success p:last-child {\r\n    margin-bottom: 0;\r\n  }\r\n\r\n  \/* =========================================================\r\n     SENSOR WIRING\r\n  ========================================================= *\/\r\n\r\n  .ly24v-wire-grid {\r\n    display: grid;\r\n    grid-template-columns: repeat(3, minmax(0, 1fr));\r\n    align-items: stretch;\r\n    gap: 17px;\r\n  }\r\n\r\n  .ly24v-wire-card {\r\n    display: flex;\r\n    flex-direction: column;\r\n    min-width: 0;\r\n    padding: 24px;\r\n    border: 1px solid var(--ly24v-line);\r\n    border-radius: 15px;\r\n    background: var(--ly24v-white);\r\n  }\r\n\r\n  .ly24v-wire-title {\r\n    display: flex;\r\n    align-items: flex-start;\r\n    gap: 12px;\r\n    margin-bottom: 15px;\r\n  }\r\n\r\n  .ly24v-wire-number {\r\n    display: inline-grid;\r\n    place-items: center;\r\n    flex: 0 0 auto;\r\n    width: 39px;\r\n    height: 39px;\r\n    margin-top: 1px;\r\n    border-radius: 50%;\r\n    background: var(--ly24v-primary);\r\n    color: var(--ly24v-white);\r\n    font-size: 16px;\r\n    font-weight: 900;\r\n  }\r\n\r\n  .ly24v-wire-title h3 {\r\n    margin: 0;\r\n    font-size: 21px;\r\n    line-height: 1.3;\r\n  }\r\n\r\n  .ly24v-wire-card > p {\r\n    font-size: 15px;\r\n  }\r\n\r\n  .ly24v-wire-card ul {\r\n    margin-top: auto;\r\n    font-size: 14px;\r\n    line-height: 1.53;\r\n  }\r\n\r\n  .ly24v-mini-lines {\r\n    display: grid;\r\n    gap: 8px;\r\n    margin: 17px 0;\r\n    padding: 14px;\r\n    border-radius: 11px;\r\n    background: var(--ly24v-bg);\r\n  }\r\n\r\n  .ly24v-mini-line {\r\n    display: grid;\r\n    grid-template-columns: 64px minmax(25px, 1fr) 72px;\r\n    align-items: center;\r\n    gap: 7px;\r\n    color: var(--ly24v-muted);\r\n    font-size: 11px;\r\n    font-weight: 800;\r\n  }\r\n\r\n  .ly24v-mini-line::before {\r\n    content: \"\";\r\n    grid-column: 2;\r\n    height: 3px;\r\n    border-radius: 999px;\r\n    background: var(--ly24v-primary);\r\n  }\r\n\r\n  .ly24v-mini-line span:first-child {\r\n    grid-column: 1;\r\n    grid-row: 1;\r\n  }\r\n\r\n  .ly24v-mini-line span:last-child {\r\n    grid-column: 3;\r\n    grid-row: 1;\r\n    text-align: right;\r\n  }\r\n\r\n  \/* =========================================================\r\n     CHECKLISTS\r\n  ========================================================= *\/\r\n\r\n  .ly24v-check-grid {\r\n    display: grid;\r\n    grid-template-columns: repeat(2, minmax(0, 1fr));\r\n    gap: 13px;\r\n  }\r\n\r\n  .ly24v-check {\r\n    display: grid;\r\n    grid-template-columns: 34px minmax(0, 1fr);\r\n    gap: 12px;\r\n    min-width: 0;\r\n    padding: 17px;\r\n    border: 1px solid var(--ly24v-line);\r\n    border-radius: 13px;\r\n    background: var(--ly24v-white);\r\n  }\r\n\r\n  .ly24v-check-icon {\r\n    display: inline-grid;\r\n    place-items: center;\r\n    width: 31px;\r\n    height: 31px;\r\n    border-radius: 9px;\r\n    background: var(--ly24v-primary-soft);\r\n    color: var(--ly24v-primary);\r\n    font-size: 13px;\r\n    font-weight: 900;\r\n  }\r\n\r\n  .ly24v-check strong {\r\n    display: block;\r\n    margin-bottom: 4px;\r\n    color: var(--ly24v-ink);\r\n  }\r\n\r\n  .ly24v-check p {\r\n    margin: 0;\r\n    color: var(--ly24v-muted);\r\n    font-size: 14px;\r\n    line-height: 1.5;\r\n  }\r\n\r\n  \/* =========================================================\r\n     EXAMPLES\r\n  ========================================================= *\/\r\n\r\n  .ly24v-example-grid {\r\n    display: grid;\r\n    grid-template-columns: repeat(2, minmax(0, 1fr));\r\n    gap: 17px;\r\n  }\r\n\r\n  .ly24v-example {\r\n    min-width: 0;\r\n    padding: 23px;\r\n    border: 1px solid var(--ly24v-line);\r\n    border-radius: 15px;\r\n    background: var(--ly24v-white);\r\n  }\r\n\r\n  .ly24v-example-label {\r\n    display: inline-block;\r\n    margin-bottom: 9px;\r\n    color: var(--ly24v-primary);\r\n    font-size: 12px;\r\n    font-weight: 900;\r\n    letter-spacing: 0.065em;\r\n    text-transform: uppercase;\r\n  }\r\n\r\n  .ly24v-example h3 {\r\n    font-size: 20px;\r\n  }\r\n\r\n  .ly24v-example ul {\r\n    font-size: 15px;\r\n    line-height: 1.55;\r\n  }\r\n\r\n  \/* =========================================================\r\n     PRODUCT BOUNDARY\r\n  ========================================================= *\/\r\n\r\n  .ly24v-product-boundary {\r\n    display: grid;\r\n    grid-template-columns: minmax(0, 1.35fr) minmax(300px, 0.65fr);\r\n    align-items: start;\r\n    gap: 28px;\r\n    padding: 32px;\r\n    border: 1px solid #acc8e6;\r\n    border-radius: 20px;\r\n    background:\r\n      linear-gradient(\r\n        135deg,\r\n        var(--ly24v-primary-soft),\r\n        var(--ly24v-white) 72%\r\n      );\r\n  }\r\n\r\n  .ly24v-product-main {\r\n    min-width: 0;\r\n  }\r\n\r\n  .ly24v-product-boundary h2 {\r\n    font-size: 30px;\r\n  }\r\n\r\n  .ly24v-product-columns {\r\n    display: grid;\r\n    grid-template-columns: repeat(2, minmax(0, 1fr));\r\n    align-items: start;\r\n    gap: 14px;\r\n    margin-top: 20px;\r\n  }\r\n\r\n  .ly24v-product-card {\r\n    min-width: 0;\r\n    padding: 19px;\r\n    border: 1px solid #c9dbed;\r\n    border-radius: 13px;\r\n    background: rgba(255, 255, 255, 0.88);\r\n  }\r\n\r\n  .ly24v-product-card h3 {\r\n    margin-bottom: 10px;\r\n    font-size: 18px;\r\n    line-height: 1.35;\r\n  }\r\n\r\n  .ly24v-product-card ul {\r\n    font-size: 14px;\r\n    line-height: 1.52;\r\n  }\r\n\r\n  .ly24v-product-card.is-confirmed {\r\n    border-top: 4px solid #278359;\r\n  }\r\n\r\n  .ly24v-product-card.is-review {\r\n    border-top: 4px solid #d18c16;\r\n  }\r\n\r\n  .ly24v-product-side {\r\n    align-self: start;\r\n    min-width: 0;\r\n    padding: 26px;\r\n    border-radius: 16px;\r\n    background: var(--ly24v-primary);\r\n    color: var(--ly24v-white);\r\n  }\r\n\r\n  .ly24v-product-side h3 {\r\n    margin-bottom: 12px;\r\n    color: var(--ly24v-white);\r\n    font-size: 22px;\r\n    line-height: 1.3;\r\n  }\r\n\r\n  .ly24v-product-side p,\r\n  .ly24v-product-side li {\r\n    color: var(--ly24v-white);\r\n  }\r\n\r\n  .ly24v-product-side p,\r\n  .ly24v-product-side ul {\r\n    font-size: 14px;\r\n  }\r\n\r\n  .ly24v-product-side ul {\r\n    margin-bottom: 21px;\r\n    padding-left: 20px;\r\n  }\r\n\r\n  \/* =========================================================\r\n     BUTTONS\r\n  ========================================================= *\/\r\n\r\n  .ly24v-button-row {\r\n    display: flex;\r\n    flex-wrap: wrap;\r\n    gap: 11px;\r\n    margin-top: 21px;\r\n  }\r\n\r\n  .ly24v-btn {\r\n    display: inline-flex !important;\r\n    align-items: center;\r\n    justify-content: center;\r\n    width: auto;\r\n    min-height: 48px;\r\n    padding: 12px 19px;\r\n    border: 2px solid var(--ly24v-primary);\r\n    border-radius: 9px;\r\n    background: var(--ly24v-primary);\r\n    color: var(--ly24v-white) !important;\r\n    font-size: 15px;\r\n    font-weight: 850;\r\n    line-height: 1.2;\r\n    text-align: center;\r\n    text-decoration: none !important;\r\n    cursor: pointer;\r\n    transition:\r\n      transform 0.2s ease,\r\n      background 0.2s ease,\r\n      border-color 0.2s ease;\r\n  }\r\n\r\n  .ly24v-btn > span {\r\n    display: block !important;\r\n    visibility: visible !important;\r\n    opacity: 1 !important;\r\n    color: var(--ly24v-white) !important;\r\n    font: inherit !important;\r\n    line-height: 1.25 !important;\r\n    text-align: center;\r\n    text-decoration: none !important;\r\n    overflow-wrap: normal !important;\r\n    word-break: normal !important;\r\n  }\r\n\r\n  .ly24v-btn:hover {\r\n    border-color: var(--ly24v-primary-dark);\r\n    background: var(--ly24v-primary-dark);\r\n    transform: translateY(-1px);\r\n  }\r\n\r\n  .ly24v-btn-outline {\r\n    background: transparent;\r\n    color: var(--ly24v-primary) !important;\r\n  }\r\n\r\n  .ly24v-btn-outline > span {\r\n    color: var(--ly24v-primary) !important;\r\n  }\r\n\r\n  .ly24v-btn-outline:hover {\r\n    background: var(--ly24v-primary);\r\n  }\r\n\r\n  .ly24v-btn-outline:hover > span {\r\n    color: var(--ly24v-white) !important;\r\n  }\r\n\r\n  .ly24v-btn-light {\r\n    border-color: var(--ly24v-white);\r\n    background: var(--ly24v-white);\r\n    color: var(--ly24v-primary) !important;\r\n  }\r\n\r\n  .ly24v-btn-light > span {\r\n    color: var(--ly24v-primary) !important;\r\n  }\r\n\r\n  .ly24v-btn-light:hover {\r\n    border-color: #dceafb;\r\n    background: #dceafb;\r\n  }\r\n\r\n  .ly24v-btn-light:hover > span {\r\n    color: var(--ly24v-primary-dark) !important;\r\n  }\r\n\r\n  \/* =========================================================\r\n     MISTAKES\r\n  ========================================================= *\/\r\n\r\n  .ly24v-mistake-grid {\r\n    display: grid;\r\n    grid-template-columns: repeat(2, minmax(0, 1fr));\r\n    gap: 14px;\r\n  }\r\n\r\n  .ly24v-mistake {\r\n    display: grid;\r\n    grid-template-columns: 34px minmax(0, 1fr);\r\n    gap: 12px;\r\n    min-width: 0;\r\n    padding: 18px;\r\n    border: 1px solid #e5afab;\r\n    border-radius: 13px;\r\n    background: var(--ly24v-red-bg);\r\n  }\r\n\r\n  .ly24v-mistake-icon {\r\n    display: inline-grid;\r\n    place-items: center;\r\n    width: 31px;\r\n    height: 31px;\r\n    border-radius: 50%;\r\n    background: var(--ly24v-red);\r\n    color: var(--ly24v-white);\r\n    font-size: 16px;\r\n    font-weight: 900;\r\n  }\r\n\r\n  .ly24v-mistake strong {\r\n    display: block;\r\n    margin-bottom: 4px;\r\n    color: var(--ly24v-ink);\r\n  }\r\n\r\n  .ly24v-mistake p {\r\n    margin: 0;\r\n    font-size: 14px;\r\n    line-height: 1.5;\r\n  }\r\n\r\n  \/* =========================================================\r\n     ORDERING\r\n  ========================================================= *\/\r\n\r\n  .ly24v-order-box {\r\n    display: grid;\r\n    grid-template-columns: minmax(0, 1fr) 320px;\r\n    align-items: start;\r\n    gap: 26px;\r\n    padding: 30px;\r\n    border: 1px solid var(--ly24v-line);\r\n    border-radius: 18px;\r\n    background: var(--ly24v-bg);\r\n  }\r\n\r\n  .ly24v-order-main {\r\n    min-width: 0;\r\n  }\r\n\r\n  .ly24v-order-main h3 {\r\n    margin-bottom: 18px;\r\n  }\r\n\r\n  .ly24v-order-list {\r\n    display: grid;\r\n    grid-template-columns: repeat(2, minmax(0, 1fr));\r\n    gap: 11px;\r\n    padding-left: 0 !important;\r\n    list-style: none;\r\n  }\r\n\r\n  .ly24v-order-list li {\r\n    display: grid;\r\n    grid-template-columns: 28px minmax(0, 1fr);\r\n    align-items: start;\r\n    gap: 9px;\r\n    min-width: 0;\r\n    margin: 0 !important;\r\n    padding: 13px 14px;\r\n    border: 1px solid #e0e7ef;\r\n    border-radius: 11px;\r\n    background: var(--ly24v-white);\r\n    font-size: 14px;\r\n    line-height: 1.48;\r\n  }\r\n\r\n  .ly24v-order-list li::before {\r\n    content: \"\u2713\";\r\n    display: inline-grid;\r\n    place-items: center;\r\n    width: 25px;\r\n    height: 25px;\r\n    border-radius: 7px;\r\n    background: var(--ly24v-primary-soft);\r\n    color: var(--ly24v-primary);\r\n    font-size: 13px;\r\n    font-weight: 900;\r\n  }\r\n\r\n  .ly24v-order-side {\r\n    align-self: start;\r\n    min-width: 0;\r\n    padding: 22px;\r\n    border-radius: 14px;\r\n    background: var(--ly24v-white);\r\n    box-shadow: 0 8px 25px rgba(26, 46, 74, 0.08);\r\n  }\r\n\r\n  .ly24v-order-side h3 {\r\n    font-size: 20px;\r\n  }\r\n\r\n  .ly24v-order-side p {\r\n    font-size: 14px;\r\n  }\r\n\r\n  \/* =========================================================\r\n     FAQ\r\n  ========================================================= *\/\r\n\r\n  .ly24v-faq-list {\r\n    display: grid;\r\n    gap: 12px;\r\n  }\r\n\r\n  .ly24v-faq {\r\n    border: 1px solid var(--ly24v-line);\r\n    border-radius: 13px;\r\n    background: var(--ly24v-white);\r\n    overflow: hidden;\r\n  }\r\n\r\n  .ly24v-faq summary {\r\n    position: relative;\r\n    padding: 18px 51px 18px 20px;\r\n    color: var(--ly24v-ink);\r\n    font-size: 17px;\r\n    font-weight: 850;\r\n    line-height: 1.45;\r\n    cursor: pointer;\r\n    list-style: none;\r\n  }\r\n\r\n  .ly24v-faq summary::-webkit-details-marker {\r\n    display: none;\r\n  }\r\n\r\n  .ly24v-faq summary::after {\r\n    content: \"+\";\r\n    position: absolute;\r\n    top: 50%;\r\n    right: 19px;\r\n    width: 25px;\r\n    height: 25px;\r\n    transform: translateY(-50%);\r\n    color: var(--ly24v-primary);\r\n    font-size: 25px;\r\n    font-weight: 500;\r\n    line-height: 23px;\r\n    text-align: center;\r\n  }\r\n\r\n  .ly24v-faq[open] summary::after {\r\n    content: \"\u2212\";\r\n  }\r\n\r\n  .ly24v-faq-answer {\r\n    padding: 0 20px 19px;\r\n  }\r\n\r\n  .ly24v-faq-answer p:last-child {\r\n    margin-bottom: 0;\r\n  }\r\n\r\n  \/* =========================================================\r\n     RELATED \/ REFERENCES\r\n  ========================================================= *\/\r\n\r\n  .ly24v-related {\r\n    display: grid;\r\n    grid-template-columns: repeat(3, minmax(0, 1fr));\r\n    gap: 14px;\r\n  }\r\n\r\n  .ly24v-related a {\r\n    display: block;\r\n    min-width: 0;\r\n    padding: 20px;\r\n    border: 1px solid var(--ly24v-line);\r\n    border-radius: 13px;\r\n    background: var(--ly24v-white);\r\n    color: var(--ly24v-ink);\r\n    font-weight: 850;\r\n    line-height: 1.45;\r\n    text-decoration: none;\r\n    transition:\r\n      transform 0.2s ease,\r\n      border-color 0.2s ease,\r\n      box-shadow 0.2s ease;\r\n  }\r\n\r\n  .ly24v-related a:hover {\r\n    border-color: #a7c3e2;\r\n    box-shadow: 0 8px 24px rgba(26, 50, 83, 0.08);\r\n    transform: translateY(-2px);\r\n  }\r\n\r\n  .ly24v-related span {\r\n    display: block;\r\n    margin-top: 7px;\r\n    color: var(--ly24v-muted);\r\n    font-size: 13px;\r\n    font-weight: 500;\r\n  }\r\n\r\n  .ly24v-references {\r\n    padding: 26px;\r\n    border-top: 3px solid var(--ly24v-primary);\r\n    border-radius: 0 0 14px 14px;\r\n    background: var(--ly24v-bg);\r\n  }\r\n\r\n  .ly24v-references h2 {\r\n    font-size: 26px;\r\n  }\r\n\r\n  .ly24v-references ol {\r\n    padding-left: 23px;\r\n    font-size: 14px;\r\n    line-height: 1.63;\r\n  }\r\n\r\n  .ly24v-references li + li {\r\n    margin-top: 10px;\r\n  }\r\n\r\n  .ly24v-references a {\r\n    overflow-wrap: anywhere;\r\n    word-break: break-word;\r\n  }\r\n\r\n  \/* =========================================================\r\n     FINAL CTA\r\n  ========================================================= *\/\r\n\r\n  .ly24v-final-cta {\r\n    margin-top: 52px;\r\n    padding: 33px;\r\n    border-radius: 20px;\r\n    background: var(--ly24v-primary);\r\n    color: var(--ly24v-white);\r\n    text-align: center;\r\n  }\r\n\r\n  .ly24v-final-cta h2,\r\n  .ly24v-final-cta p {\r\n    color: var(--ly24v-white);\r\n  }\r\n\r\n  .ly24v-final-cta h2 {\r\n    margin-bottom: 11px;\r\n    font-size: 30px;\r\n  }\r\n\r\n  .ly24v-final-cta p {\r\n    max-width: 790px;\r\n    margin: 0 auto 21px;\r\n    opacity: 0.95;\r\n  }\r\n\r\n  .ly24v-final-cta .ly24v-button-row {\r\n    justify-content: center;\r\n    margin-top: 0;\r\n  }\r\n\r\n  \/* =========================================================\r\n     CONTAINER RESPONSIVE RULES\r\n  ========================================================= *\/\r\n\r\n  @container ly24v (max-width: 1080px) {\r\n    .ly24v-selection-grid {\r\n      grid-template-columns: repeat(2, minmax(0, 1fr));\r\n    }\r\n\r\n    .ly24v-card-grid {\r\n      grid-template-columns: repeat(2, minmax(0, 1fr));\r\n    }\r\n\r\n    .ly24v-wire-grid {\r\n      grid-template-columns: repeat(2, minmax(0, 1fr));\r\n    }\r\n\r\n    .ly24v-product-boundary {\r\n      grid-template-columns: 1fr;\r\n    }\r\n\r\n    .ly24v-product-side {\r\n      width: 100%;\r\n    }\r\n  }\r\n\r\n  @container ly24v (max-width: 920px) {\r\n    .ly24v-order-box {\r\n      grid-template-columns: 1fr;\r\n    }\r\n\r\n    .ly24v-order-side {\r\n      width: 100%;\r\n    }\r\n\r\n    .ly24v-related {\r\n      grid-template-columns: 1fr;\r\n    }\r\n  }\r\n\r\n  @container ly24v (max-width: 820px) {\r\n    .ly24v-toc ol,\r\n    .ly24v-scope,\r\n    .ly24v-check-grid,\r\n    .ly24v-example-grid,\r\n    .ly24v-mistake-grid {\r\n      grid-template-columns: 1fr;\r\n    }\r\n\r\n    .ly24v-wire-grid {\r\n      grid-template-columns: 1fr;\r\n    }\r\n\r\n    .ly24v-product-columns {\r\n      grid-template-columns: 1fr;\r\n    }\r\n  }\r\n\r\n  @container ly24v (max-width: 740px) {\r\n    .ly24v-selection-grid {\r\n      grid-template-columns: 1fr;\r\n    }\r\n\r\n    .ly24v-order-list {\r\n      grid-template-columns: 1fr;\r\n    }\r\n  }\r\n\r\n  @container ly24v (max-width: 760px) {\r\n    .ly24v-table-wrap {\r\n      max-height: none;\r\n      overflow: visible;\r\n      border: 0;\r\n      border-radius: 0;\r\n      background: transparent;\r\n      box-shadow: none;\r\n    }\r\n\r\n    .ly24v-responsive-table {\r\n      min-width: 0;\r\n      border: 0;\r\n    }\r\n\r\n    .ly24v-responsive-table thead {\r\n      display: none;\r\n    }\r\n\r\n    .ly24v-responsive-table,\r\n    .ly24v-responsive-table tbody,\r\n    .ly24v-responsive-table tr,\r\n    .ly24v-responsive-table td {\r\n      display: block;\r\n      width: 100%;\r\n    }\r\n\r\n    .ly24v-responsive-table tr {\r\n      margin-bottom: 15px;\r\n      border: 1px solid var(--ly24v-line);\r\n      border-radius: 13px;\r\n      background: var(--ly24v-white);\r\n      overflow: hidden;\r\n      box-shadow: 0 5px 16px rgba(24, 46, 75, 0.045);\r\n    }\r\n\r\n    .ly24v-responsive-table td {\r\n      width: 100% !important;\r\n      min-width: 0 !important;\r\n      padding: 14px 15px;\r\n      border-right: 0;\r\n      border-bottom: 1px solid var(--ly24v-line);\r\n    }\r\n\r\n    .ly24v-responsive-table td:last-child {\r\n      border-bottom: 0;\r\n    }\r\n\r\n    .ly24v-responsive-table td::before {\r\n      content: attr(data-label);\r\n      display: block;\r\n      margin-bottom: 5px;\r\n      color: var(--ly24v-primary);\r\n      font-size: 11px;\r\n      font-weight: 900;\r\n      letter-spacing: 0.05em;\r\n      text-transform: uppercase;\r\n    }\r\n  }\r\n\r\n  \/* =========================================================\r\n     VIEWPORT RESPONSIVE RULES\r\n  ========================================================= *\/\r\n\r\n  @media (max-width: 1440px) {\r\n    .ly24v-page {\r\n      max-width: 1160px;\r\n      padding-right: 23px;\r\n      padding-left: 23px;\r\n    }\r\n  }\r\n\r\n  @media (max-width: 1366px) {\r\n    .ly24v-page {\r\n      max-width: 1120px;\r\n      padding-top: 32px;\r\n    }\r\n\r\n    .ly24v-section {\r\n      margin-top: 60px;\r\n    }\r\n  }\r\n\r\n  @media (max-width: 1280px) {\r\n    .ly24v-page {\r\n      max-width: 1080px;\r\n      font-size: 16.5px;\r\n    }\r\n\r\n    .ly24v-intro h2 {\r\n      font-size: 36px;\r\n    }\r\n  }\r\n\r\n  @media (max-width: 1024px) {\r\n    .ly24v-page {\r\n      max-width: 960px;\r\n      padding: 28px 22px 56px;\r\n    }\r\n\r\n    .ly24v-intro {\r\n      padding: 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padding-left: 16px;\r\n    }\r\n  }\r\n\r\n  @media (max-width: 375px) {\r\n    .ly24v-page h2 {\r\n      font-size: 23px;\r\n    }\r\n\r\n    .ly24v-page h3 {\r\n      font-size: 18px;\r\n    }\r\n\r\n    .ly24v-intro h2 {\r\n      font-size: 22px;\r\n    }\r\n\r\n    .ly24v-faq summary {\r\n      padding: 16px 45px 16px 16px;\r\n      font-size: 16px;\r\n    }\r\n\r\n    .ly24v-faq-answer {\r\n      padding: 0 16px 16px;\r\n    }\r\n  }\r\n\r\n  @media (max-width: 360px) {\r\n    .ly24v-page {\r\n      padding-right: 12px;\r\n      padding-left: 12px;\r\n    }\r\n\r\n    .ly24v-intro {\r\n      padding: 19px 16px;\r\n    }\r\n\r\n    .ly24v-btn {\r\n      padding-right: 13px;\r\n      padding-left: 13px;\r\n      font-size: 14px;\r\n    }\r\n  }\r\n\r\n  @media (max-width: 320px) {\r\n    .ly24v-page {\r\n      padding-right: 10px;\r\n      padding-left: 10px;\r\n      font-size: 15px;\r\n    }\r\n\r\n    .ly24v-intro {\r\n      padding: 17px 13px;\r\n    }\r\n\r\n    .ly24v-intro h2,\r\n    .ly24v-page h2 {\r\n      font-size: 21px;\r\n    }\r\n\r\n    .ly24v-tag {\r\n      width: 100%;\r\n      justify-content: center;\r\n      text-align: center;\r\n    }\r\n\r\n    .ly24v-product-boundary,\r\n    .ly24v-order-box,\r\n    .ly24v-final-cta {\r\n      padding: 19px 13px;\r\n    }\r\n  }\r\n<\/style>\r\n\r\n<article class=\"ly24v-page\">\r\n\r\n  <section class=\"ly24v-intro\" aria-labelledby=\"ly24v-intro-heading\">\r\n\r\n    <div class=\"ly24v-kicker\">\r\n      Industrial Signal Protection \u00b7 PLC I\/O \u00b7 OEM Selection\r\n    <\/div>\r\n\r\n    <div id=\"ez-toc-container\" class=\"ez-toc-v2_0_85 counter-hierarchy ez-toc-counter ez-toc-custom ez-toc-container-direction\">\n<div class=\"ez-toc-title-container\">\n<p class=\"ez-toc-title\" style=\"cursor:inherit\">Table of Contents<\/p>\n<span class=\"ez-toc-title-toggle\"><\/span><\/div>\n<nav><ul class='ez-toc-list ez-toc-list-level-1 ' ><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-1\" href=\"#\" data-href=\"https:\/\/www.cnspd.com\/pt\/24v-signal-surge-protector\/#how-to-select-a-24v-signal-surge-protector\" >How to Select a 24V Signal Surge Protector<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-2\" href=\"#\" data-href=\"https:\/\/www.cnspd.com\/pt\/24v-signal-surge-protector\/#24v-signal-spd-quick-selection-guide\" >24V Signal SPD Quick Selection Guide<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-3\" href=\"#\" data-href=\"https:\/\/www.cnspd.com\/pt\/24v-signal-surge-protector\/#when-does-a-24v-sensor-or-plc-io-line-need-an-spd\" >When Does a 24V Sensor or PLC I\/O Line Need an SPD?<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-4\" href=\"#\" data-href=\"https:\/\/www.cnspd.com\/pt\/24v-signal-surge-protector\/#24v-dc-power-spd-vs-24v-signal-spd\" >24V DC Power SPD vs 24V Signal SPD<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-5\" href=\"#\" data-href=\"https:\/\/www.cnspd.com\/pt\/24v-signal-surge-protector\/#how-di-do-ai-and-ao-change-signal-spd-selection\" >How DI, DO, AI and AO Change Signal SPD Selection<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-6\" href=\"#\" data-href=\"https:\/\/www.cnspd.com\/pt\/24v-signal-surge-protector\/#two-three-and-four-wire-sensors-need-different-protection-paths\" >Two-, Three- and Four-Wire Sensors Need Different Protection Paths<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-7\" href=\"#\" data-href=\"https:\/\/www.cnspd.com\/pt\/24v-signal-surge-protector\/#install-the-spd-at-the-field-end-cabinet-end-or-both-ends\" >Install the SPD at the Field End, Cabinet End or Both Ends?<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-8\" href=\"#\" data-href=\"https:\/\/www.cnspd.com\/pt\/24v-signal-surge-protector\/#grounding-and-shield-handling-for-a-24v-signal-spd\" >Grounding and Shield Handling for a 24V Signal SPD<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-9\" href=\"#\" data-href=\"https:\/\/www.cnspd.com\/pt\/24v-signal-surge-protector\/#parameters-to-confirm-before-choosing-the-spd\" >Parameters to Confirm Before Choosing the SPD<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-10\" href=\"#\" data-href=\"https:\/\/www.cnspd.com\/pt\/24v-signal-surge-protector\/#practical-24v-sensor-and-plc-io-selection-examples\" >Practical 24V Sensor and PLC I\/O Selection Examples<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-11\" href=\"#\" data-href=\"https:\/\/www.cnspd.com\/pt\/24v-signal-surge-protector\/#where-ly10-fits%e2%80%94and-where-separate-confirmation-is-required\" >Where LY10 Fits\u2014and Where Separate Confirmation Is Required<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-12\" href=\"#\" data-href=\"https:\/\/www.cnspd.com\/pt\/24v-signal-surge-protector\/#common-selection-and-installation-mistakes\" >Common Selection and Installation Mistakes<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-13\" href=\"#\" data-href=\"https:\/\/www.cnspd.com\/pt\/24v-signal-surge-protector\/#what-an-oem-buyer-or-panel-builder-should-confirm\" >What an OEM Buyer or Panel Builder Should Confirm<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-14\" href=\"#\" data-href=\"https:\/\/www.cnspd.com\/pt\/24v-signal-surge-protector\/#24v-signal-surge-protector-faq\" >24V Signal Surge Protector FAQ<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-15\" href=\"#\" data-href=\"https:\/\/www.cnspd.com\/pt\/24v-signal-surge-protector\/#keep-each-protection-topic-separate\" >Keep Each Protection Topic Separate<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-16\" href=\"#\" data-href=\"https:\/\/www.cnspd.com\/pt\/24v-signal-surge-protector\/#technical-references\" >Technical References<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-17\" href=\"#\" data-href=\"https:\/\/www.cnspd.com\/pt\/24v-signal-surge-protector\/#need-a-24v-signal-spd-for-a-real-plc-io-circuit\" >Need a 24V Signal SPD for a Real PLC I\/O Circuit?<\/a><\/li><\/ul><\/nav><\/div>\n<h2 id=\"ly24v-intro-heading\"><span class=\"ez-toc-section\" id=\"how-to-select-a-24v-signal-surge-protector\"><\/span>\r\n      How to Select a 24V Signal Surge Protector\r\n    <span class=\"ez-toc-section-end\"><\/span><\/h2>\r\n\r\n    <p class=\"ly24v-lead\">\r\n      A 24V marking alone is not enough to select a surge protector for a\r\n      sensor or PLC I\/O circuit. The correct SPD must also match the signal\r\n      type, circuit topology, conductor count, loop current, permissible\r\n      series resistance, protection level and installation position.\r\n    <\/p>\r\n\r\n    <div class=\"ly24v-tags\" aria-label=\"Signals covered by this guide\">\r\n      <span class=\"ly24v-tag\">PLC DI<\/span>\r\n      <span class=\"ly24v-tag\">PLC DO<\/span>\r\n      <span class=\"ly24v-tag\">PLC AI<\/span>\r\n      <span class=\"ly24v-tag\">PLC AO<\/span>\r\n      <span class=\"ly24v-tag\">4\u201320mA<\/span>\r\n      <span class=\"ly24v-tag\">0\u201310V<\/span>\r\n      <span class=\"ly24v-tag\">PNP \/ NPN Sensors<\/span>\r\n      <span class=\"ly24v-tag\">Two-, Three- and Four-Wire Circuits<\/span>\r\n    <\/div>\r\n\r\n    <div class=\"ly24v-direct-answer\">\r\n\r\n      <div class=\"ly24v-direct-label\">\r\n        Quick Answer\r\n      <\/div>\r\n\r\n      <p>\r\n        Use a signal-line SPD\u2014not a general 24V DC power SPD\u2014when an external\r\n        sensor, transmitter, switch or actuator is connected to a PLC I\/O\r\n        channel. Select the SPD according to DI, DO, AI or AO function. For\r\n        analog circuits, confirm series resistance, leakage current,\r\n        capacitance and loop-voltage margin before approving the model.\r\n      <\/p>\r\n\r\n    <\/div>\r\n\r\n    <div class=\"ly24v-scope\">\r\n\r\n      <div class=\"ly24v-scope-card is-in\">\r\n\r\n        <strong>\r\n          This page covers\r\n        <\/strong>\r\n\r\n        <p>\r\n          24V sensor and PLC I\/O circuits, including digital switching,\r\n          4\u201320mA, 0\u201310V, conductor arrangement, field installation and\r\n          cabinet-entry protection.\r\n        <\/p>\r\n\r\n      <\/div>\r\n\r\n      <div class=\"ly24v-scope-card is-out\">\r\n\r\n        <strong>\r\n          This page does not cover\r\n        <\/strong>\r\n\r\n        <p>\r\n          General 24V DC power buses, 48V telecom power, solar PV DC circuits\r\n          or RS485 protocol wiring. Those applications require separate\r\n          selection rules.\r\n        <\/p>\r\n\r\n      <\/div>\r\n\r\n    <\/div>\r\n\r\n  <\/section>\r\n\r\n  <nav class=\"ly24v-toc\" aria-label=\"Table of contents\">\r\n\r\n    <div class=\"ly24v-toc-title\">\r\n      In This Guide\r\n    <\/div>\r\n\r\n    <ol>\r\n      <li><a href=\"#ly24v-quick-selection\">Quick selection guide<\/a><\/li>\r\n      <li><a href=\"#ly24v-risk\">When a 24V signal line needs protection<\/a><\/li>\r\n      <li><a href=\"#ly24v-power-vs-signal\">Power SPD vs signal SPD<\/a><\/li>\r\n      <li><a href=\"#ly24v-io-selection\">DI, DO, AI and AO selection<\/a><\/li>\r\n      <li><a href=\"#ly24v-wiring\">Two-, three- and four-wire sensors<\/a><\/li>\r\n      <li><a href=\"#ly24v-location\">Field side, cabinet side or both<\/a><\/li>\r\n      <li><a href=\"#ly24v-grounding\">Grounding and shield handling<\/a><\/li>\r\n      <li><a href=\"#ly24v-parameters\">Parameters to confirm<\/a><\/li>\r\n      <li><a href=\"#ly24v-examples\">Application examples<\/a><\/li>\r\n      <li><a href=\"#ly24v-product-boundary\">LEEYEE product boundary<\/a><\/li>\r\n      <li><a href=\"#ly24v-ordering\">OEM ordering checklist<\/a><\/li>\r\n      <li><a href=\"#ly24v-faq\">Frequently asked questions<\/a><\/li>\r\n    <\/ol>\r\n\r\n  <\/nav>\r\n\r\n  <section class=\"ly24v-section\" id=\"ly24v-quick-selection\">\r\n\r\n    <div class=\"ly24v-section-head\">\r\n\r\n      <div class=\"ly24v-kicker\">\r\n        Selection Shortcut\r\n      <\/div>\r\n\r\n      <h2><span class=\"ez-toc-section\" id=\"24v-signal-spd-quick-selection-guide\"><\/span>\r\n        24V Signal SPD Quick Selection Guide\r\n      <span class=\"ez-toc-section-end\"><\/span><\/h2>\r\n\r\n      <p>\r\n        Start with the actual circuit. Do not select from the nominal voltage\r\n        alone.\r\n      <\/p>\r\n\r\n    <\/div>\r\n\r\n    <div class=\"ly24v-selection-grid\">\r\n\r\n      <article class=\"ly24v-selection-card\">\r\n\r\n        <div class=\"ly24v-selection-card-head\">\r\n\r\n          <span class=\"ly24v-selection-type\">\r\n            Two-Wire 4\u201320mA AI\r\n          <\/span>\r\n\r\n          <span class=\"ly24v-selection-device\">\r\n            Pressure, level, flow or temperature transmitter\r\n          <\/span>\r\n\r\n        <\/div>\r\n\r\n        <div class=\"ly24v-selection-body\">\r\n\r\n          <span class=\"ly24v-selection-label\">\r\n            What the SPD Must Match\r\n          <\/span>\r\n\r\n          <p>\r\n            Floating loop or reference arrangement, maximum loop voltage,\r\n            loop current, low series resistance, low leakage and HART\r\n            compatibility where required.\r\n          <\/p>\r\n\r\n          <span class=\"ly24v-selection-status is-confirm\">\r\n            Model confirmation required\r\n          <\/span>\r\n\r\n        <\/div>\r\n\r\n      <\/article>\r\n\r\n      <article class=\"ly24v-selection-card\">\r\n\r\n        <div class=\"ly24v-selection-card-head\">\r\n\r\n          <span class=\"ly24v-selection-type\">\r\n            Three-Wire PNP or NPN DI\r\n          <\/span>\r\n\r\n          <span class=\"ly24v-selection-device\">\r\n            Proximity sensor, photoelectric sensor or limit switch\r\n          <\/span>\r\n\r\n        <\/div>\r\n\r\n        <div class=\"ly24v-selection-body\">\r\n\r\n          <span class=\"ly24v-selection-label\">\r\n            What the SPD Must Match\r\n          <\/span>\r\n\r\n          <p>\r\n            +24V, 0V, switching output, sourcing or sinking logic, input\r\n            threshold, leakage current and terminal arrangement.\r\n          <\/p>\r\n\r\n          <span class=\"ly24v-selection-status is-confirm\">\r\n            Wiring review required\r\n          <\/span>\r\n\r\n        <\/div>\r\n\r\n      <\/article>\r\n\r\n      <article class=\"ly24v-selection-card\">\r\n\r\n        <div class=\"ly24v-selection-card-head\">\r\n\r\n          <span class=\"ly24v-selection-type\">\r\n            24V PLC DO\r\n          <\/span>\r\n\r\n          <span class=\"ly24v-selection-device\">\r\n            Solenoid valve, interposing relay, lamp or outdoor actuator\r\n          <\/span>\r\n\r\n        <\/div>\r\n\r\n        <div class=\"ly24v-selection-body\">\r\n\r\n          <span class=\"ly24v-selection-label\">\r\n            What the SPD Must Match\r\n          <\/span>\r\n\r\n          <p>\r\n            Output type, load current, polarity, common conductor and maximum\r\n            continuous operating current.\r\n          <\/p>\r\n\r\n          <span class=\"ly24v-selection-status is-confirm\">\r\n            Load review required\r\n          <\/span>\r\n\r\n        <\/div>\r\n\r\n      <\/article>\r\n\r\n      <article class=\"ly24v-selection-card\">\r\n\r\n        <div class=\"ly24v-selection-card-head\">\r\n\r\n          <span class=\"ly24v-selection-type\">\r\n            0\u201310V AI or AO\r\n          <\/span>\r\n\r\n          <span class=\"ly24v-selection-device\">\r\n            Analog sensor, actuator, valve positioner or controller\r\n          <\/span>\r\n\r\n        <\/div>\r\n\r\n        <div class=\"ly24v-selection-body\">\r\n\r\n          <span class=\"ly24v-selection-label\">\r\n            What the SPD Must Match\r\n          <\/span>\r\n\r\n          <p>\r\n            Maximum signal voltage, reference topology, leakage current,\r\n            series resistance, capacitance and permissible signal error.\r\n          <\/p>\r\n\r\n          <span class=\"ly24v-selection-status is-confirm\">\r\n            Model confirmation required\r\n          <\/span>\r\n\r\n        <\/div>\r\n\r\n      <\/article>\r\n\r\n      <article class=\"ly24v-selection-card\">\r\n\r\n        <div class=\"ly24v-selection-card-head\">\r\n\r\n          <span class=\"ly24v-selection-type\">\r\n            RS485 or Industrial Data Line\r\n          <\/span>\r\n\r\n          <span class=\"ly24v-selection-device\">\r\n            PLC, RTU, meter, gateway or remote communication device\r\n          <\/span>\r\n\r\n        <\/div>\r\n\r\n        <div class=\"ly24v-selection-body\">\r\n\r\n          <span class=\"ly24v-selection-label\">\r\n            What the SPD Must Match\r\n          <\/span>\r\n\r\n          <p>\r\n            Interface, operating voltage, conductor count, baud rate,\r\n            capacitance, grounding and shield arrangement.\r\n          <\/p>\r\n\r\n          <span class=\"ly24v-selection-status is-product\">\r\n            LY10 product direction\r\n          <\/span>\r\n\r\n        <\/div>\r\n\r\n      <\/article>\r\n\r\n      <article class=\"ly24v-selection-card\">\r\n\r\n        <div class=\"ly24v-selection-card-head\">\r\n\r\n          <span class=\"ly24v-selection-type\">\r\n            24V DC Power Input\r\n          <\/span>\r\n\r\n          <span class=\"ly24v-selection-device\">\r\n            PLC power supply, controller supply or auxiliary DC bus\r\n          <\/span>\r\n\r\n        <\/div>\r\n\r\n        <div class=\"ly24v-selection-body\">\r\n\r\n          <span class=\"ly24v-selection-label\">\r\n            What the SPD Must Match\r\n          <\/span>\r\n\r\n          <p>\r\n            DC power voltage, maximum load current, polarity, fault conditions\r\n            and power-circuit SPD requirements.\r\n          <\/p>\r\n\r\n          <span class=\"ly24v-selection-status is-separate\">\r\n            Separate power SPD selection\r\n          <\/span>\r\n\r\n        <\/div>\r\n\r\n      <\/article>\r\n\r\n    <\/div>\r\n\r\n    <div class=\"ly24v-answer-strip\">\r\n\r\n      <strong>\r\n        The key purchasing rule\r\n      <\/strong>\r\n\r\n      <p>\r\n        State the circuit as \u201ctwo-wire 4\u201320mA AI,\u201d \u201cthree-wire PNP DI,\u201d\r\n        \u201c24V transistor DO\u201d or \u201c0\u201310V AO.\u201d A request that says only\r\n        \u201c24V SPD\u201d does not contain enough information for reliable model\r\n        selection.\r\n      <\/p>\r\n\r\n    <\/div>\r\n\r\n  <\/section>\r\n\r\n  <section class=\"ly24v-section\" id=\"ly24v-risk\">\r\n\r\n    <div class=\"ly24v-section-head\">\r\n\r\n      <div class=\"ly24v-kicker\">\r\n        Risk Assessment\r\n      <\/div>\r\n\r\n      <h2><span class=\"ez-toc-section\" id=\"when-does-a-24v-sensor-or-plc-io-line-need-an-spd\"><\/span>\r\n        When Does a 24V Sensor or PLC I\/O Line Need an SPD?\r\n      <span class=\"ez-toc-section-end\"><\/span><\/h2>\r\n\r\n      <p>\r\n        Not every internal control wire needs individual protection. The\r\n        decision depends on cable exposure, installation boundaries, equipment\r\n        sensitivity and the operational cost of failure.\r\n      <\/p>\r\n\r\n    <\/div>\r\n\r\n    <div class=\"ly24v-card-grid\">\r\n\r\n      <div class=\"ly24v-card\">\r\n\r\n        <span class=\"ly24v-card-icon\">01<\/span>\r\n\r\n        <h3>Outdoor Field Device<\/h3>\r\n\r\n        <p>\r\n          Sensors and transmitters installed outdoors can receive induced\r\n          transient voltage through their field wiring even without a direct\r\n          lightning strike.\r\n        <\/p>\r\n\r\n      <\/div>\r\n\r\n      <div class=\"ly24v-card\">\r\n\r\n        <span class=\"ly24v-card-icon\">02<\/span>\r\n\r\n        <h3>Long Cable Route<\/h3>\r\n\r\n        <p>\r\n          Long cables provide a larger coupling path for lightning effects,\r\n          switching transients and voltage differences between locations.\r\n        <\/p>\r\n\r\n      <\/div>\r\n\r\n      <div class=\"ly24v-card\">\r\n\r\n        <span class=\"ly24v-card-icon\">03<\/span>\r\n\r\n        <h3>Cross-Building Connection<\/h3>\r\n\r\n        <p>\r\n          Cabling between buildings, outdoor junction boxes or different\r\n          equipotential zones can expose both ends of the circuit.\r\n        <\/p>\r\n\r\n      <\/div>\r\n\r\n      <div class=\"ly24v-card\">\r\n\r\n        <span class=\"ly24v-card-icon\">04<\/span>\r\n\r\n        <h3>High Downtime Cost<\/h3>\r\n\r\n        <p>\r\n          Process plants, water systems, pump stations and automated production\r\n          lines may justify local protection because one failed I\/O card can\r\n          stop a larger system.\r\n        <\/p>\r\n\r\n      <\/div>\r\n\r\n    <\/div>\r\n\r\n    <div class=\"ly24v-warning\">\r\n\r\n      <strong>\r\n        Low operating voltage does not mean low transient risk.\r\n      <\/strong>\r\n\r\n      <p>\r\n        The circuit may operate at only 24V, but a transient coupled into the\r\n        cable can exceed the withstand capability of the PLC input, transmitter\r\n        or sensor interface. Surge immunity testing and signal-SPD performance\r\n        are therefore evaluated separately from the normal operating voltage.\r\n        <sup>[1][3]<\/sup>\r\n      <\/p>\r\n\r\n    <\/div>\r\n\r\n  <\/section>\r\n\r\n  <section class=\"ly24v-section\" id=\"ly24v-power-vs-signal\">\r\n\r\n    <div class=\"ly24v-section-head\">\r\n\r\n      <div class=\"ly24v-kicker\">\r\n        Critical Difference\r\n      <\/div>\r\n\r\n      <h2><span class=\"ez-toc-section\" id=\"24v-dc-power-spd-vs-24v-signal-spd\"><\/span>\r\n        24V DC Power SPD vs 24V Signal SPD\r\n      <span class=\"ez-toc-section-end\"><\/span><\/h2>\r\n\r\n      <p>\r\n        Both products may include \u201c24V\u201d in their description, but they protect\r\n        different circuits and cannot be selected by the same parameters.\r\n      <\/p>\r\n\r\n    <\/div>\r\n\r\n    <div class=\"ly24v-table-wrap\">\r\n\r\n      <table class=\"ly24v-table ly24v-responsive-table\">\r\n\r\n        <thead>\r\n          <tr>\r\n            <th>Selection Point<\/th>\r\n            <th>24V DC Power SPD<\/th>\r\n            <th>24V Signal SPD<\/th>\r\n          <\/tr>\r\n        <\/thead>\r\n\r\n        <tbody>\r\n\r\n          <tr>\r\n            <td data-label=\"Selection Point\">\r\n              <strong>Main purpose<\/strong>\r\n            <\/td>\r\n\r\n            <td data-label=\"24V DC Power SPD\">\r\n              Protect a DC power supply, auxiliary power bus or powered\r\n              equipment input.\r\n            <\/td>\r\n\r\n            <td data-label=\"24V Signal SPD\">\r\n              Protect PLC I\/O, sensor, transmitter or low-voltage control\r\n              conductors.\r\n            <\/td>\r\n          <\/tr>\r\n\r\n          <tr>\r\n            <td data-label=\"Selection Point\">\r\n              <strong>Normal current<\/strong>\r\n            <\/td>\r\n\r\n            <td data-label=\"24V DC Power SPD\">\r\n              May need to carry the continuous current of a complete power\r\n              load.\r\n            <\/td>\r\n\r\n            <td data-label=\"24V Signal SPD\">\r\n              Usually carries lower signal or loop current and must preserve\r\n              signal behaviour.\r\n            <\/td>\r\n          <\/tr>\r\n\r\n          <tr>\r\n            <td data-label=\"Selection Point\">\r\n              <strong>Key parameters<\/strong>\r\n            <\/td>\r\n\r\n            <td data-label=\"24V DC Power SPD\">\r\n              Uc, load current, polarity, protection level, fault conditions\r\n              and power-system topology.\r\n            <\/td>\r\n\r\n            <td data-label=\"24V Signal SPD\">\r\n              Uc, limiting voltage, leakage, series resistance, capacitance,\r\n              bandwidth and circuit topology.\r\n            <\/td>\r\n          <\/tr>\r\n\r\n          <tr>\r\n            <td data-label=\"Selection Point\">\r\n              <strong>Typical circuit<\/strong>\r\n            <\/td>\r\n\r\n            <td data-label=\"24V DC Power SPD\">\r\n              PLC power input, 24V auxiliary bus or industrial controller\r\n              power supply.\r\n            <\/td>\r\n\r\n            <td data-label=\"24V Signal SPD\">\r\n              DI, DO, 4\u201320mA, 0\u201310V and sensor or transmitter wiring.\r\n            <\/td>\r\n          <\/tr>\r\n\r\n          <tr>\r\n            <td data-label=\"Selection Point\">\r\n              <strong>Main selection risk<\/strong>\r\n            <\/td>\r\n\r\n            <td data-label=\"24V DC Power SPD\">\r\n              A power SPD may not provide the required signal characteristics\r\n              for an analog or digital I\/O circuit.\r\n            <\/td>\r\n\r\n            <td data-label=\"24V Signal SPD\">\r\n              A signal SPD may not carry the current required by a 24V DC\r\n              power load.\r\n            <\/td>\r\n          <\/tr>\r\n\r\n          <tr>\r\n            <td data-label=\"Selection Point\">\r\n              <strong>Relevant application standard<\/strong>\r\n            <\/td>\r\n\r\n            <td data-label=\"24V DC Power SPD\">\r\n              Confirm the standard and test documentation applicable to the\r\n              specific DC power circuit.\r\n            <\/td>\r\n\r\n            <td data-label=\"24V Signal SPD\">\r\n              IEC 61643-21 applies to SPDs connected to telecommunications and\r\n              signalling networks.<sup>[1]<\/sup>\r\n            <\/td>\r\n          <\/tr>\r\n\r\n        <\/tbody>\r\n\r\n      <\/table>\r\n\r\n    <\/div>\r\n\r\n    <div class=\"ly24v-note\">\r\n\r\n      <strong>\r\n        Do not use \u201cDC SPD\u201d as a complete product description.\r\n      <\/strong>\r\n\r\n      <p>\r\n        PV DC SPDs, telecom DC power SPDs, auxiliary-power SPDs and signal-line\r\n        SPDs can all operate on DC circuits, but their voltages, current paths,\r\n        test requirements and applications are different.\r\n      <\/p>\r\n\r\n    <\/div>\r\n\r\n  <\/section>\r\n\r\n  <section class=\"ly24v-section\" id=\"ly24v-io-selection\">\r\n\r\n    <div class=\"ly24v-section-head\">\r\n\r\n      <div class=\"ly24v-kicker\">\r\n        PLC Port Selection\r\n      <\/div>\r\n\r\n      <h2><span class=\"ez-toc-section\" id=\"how-di-do-ai-and-ao-change-signal-spd-selection\"><\/span>\r\n        How DI, DO, AI and AO Change Signal SPD Selection\r\n      <span class=\"ez-toc-section-end\"><\/span><\/h2>\r\n\r\n      <p>\r\n        The I\/O function tells the supplier what the circuit carries and what\r\n        must be preserved during normal operation.\r\n      <\/p>\r\n\r\n    <\/div>\r\n\r\n    <figure class=\"ly24v-figure\">\r\n\r\n      <img loading=\"lazy\"\r\n        src=\"https:\/\/www.cnspd.com\/wp-content\/uploads\/2026\/07\/plc-di-do-ai-ao-signal-spd-selection-comparison.webp\"\r\n        alt=\"Comparison of 24V signal surge protector selection for PLC DI, DO, AI and AO circuits\"\r\n        width=\"1600\"\r\n        height=\"900\"\r\n        loading=\"lazy\"\r\n        decoding=\"async\"\r\n      >\r\n\r\n      <figcaption>\r\n        DI and DO selection focuses on switching logic, current and conductor\r\n        arrangement. AI and AO circuits require additional checks for\r\n        resistance, leakage, capacitance and signal accuracy.\r\n      <\/figcaption>\r\n\r\n    <\/figure>\r\n\r\n    <div class=\"ly24v-table-wrap\">\r\n\r\n      <table class=\"ly24v-table ly24v-responsive-table\">\r\n\r\n        <thead>\r\n          <tr>\r\n            <th>PLC Function<\/th>\r\n            <th>Typical Circuit<\/th>\r\n            <th>Parameters to Confirm<\/th>\r\n            <th>Selection Warning<\/th>\r\n          <\/tr>\r\n        <\/thead>\r\n\r\n        <tbody>\r\n\r\n          <tr>\r\n            <td data-label=\"PLC Function\">\r\n              <strong>DI<\/strong>\r\n              <small>Digital input<\/small>\r\n            <\/td>\r\n\r\n            <td data-label=\"Typical Circuit\">\r\n              PNP or NPN proximity sensor, limit switch, pressure switch or\r\n              remote dry contact.\r\n            <\/td>\r\n\r\n            <td data-label=\"Parameters to Confirm\">\r\n              Maximum normal voltage, common reference, PNP\/NPN logic,\r\n              protected conductors, leakage current and input threshold.\r\n            <\/td>\r\n\r\n            <td data-label=\"Selection Warning\">\r\n              Excessive leakage can affect a sensitive input state. Do not\r\n              assign terminals before confirming sourcing or sinking logic.\r\n            <\/td>\r\n          <\/tr>\r\n\r\n          <tr>\r\n            <td data-label=\"PLC Function\">\r\n              <strong>DO<\/strong>\r\n              <small>Digital output<\/small>\r\n            <\/td>\r\n\r\n            <td data-label=\"Typical Circuit\">\r\n              Transistor or relay output controlling a valve, relay, lamp or\r\n              actuator.\r\n            <\/td>\r\n\r\n            <td data-label=\"Parameters to Confirm\">\r\n              Output type, maximum load current, polarity, common conductor\r\n              and load characteristics.\r\n            <\/td>\r\n\r\n            <td data-label=\"Selection Warning\">\r\n              A signal SPD does not replace a flyback diode or other local\r\n              suppression required for repetitive inductive switching.\r\n            <\/td>\r\n          <\/tr>\r\n\r\n          <tr>\r\n            <td data-label=\"PLC Function\">\r\n              <strong>AI<\/strong>\r\n              <small>Analog input<\/small>\r\n            <\/td>\r\n\r\n            <td data-label=\"Typical Circuit\">\r\n              4\u201320mA pressure, level or flow transmitter; 0\u201310V sensor output.\r\n            <\/td>\r\n\r\n            <td data-label=\"Parameters to Confirm\">\r\n              Loop voltage, current, series resistance, leakage, limiting\r\n              voltage, capacitance and HART compatibility where required.\r\n            <\/td>\r\n\r\n            <td data-label=\"Selection Warning\">\r\n              Added resistance or leakage can reduce loop-voltage margin or\r\n              introduce measurement error.\r\n            <\/td>\r\n          <\/tr>\r\n\r\n          <tr>\r\n            <td data-label=\"PLC Function\">\r\n              <strong>AO<\/strong>\r\n              <small>Analog output<\/small>\r\n            <\/td>\r\n\r\n            <td data-label=\"Typical Circuit\">\r\n              PLC output to a valve positioner, drive reference, actuator or\r\n              remote controller.\r\n            <\/td>\r\n\r\n            <td data-label=\"Parameters to Confirm\">\r\n              Output range, maximum loop burden, output current, added\r\n              impedance and permissible signal error.\r\n            <\/td>\r\n\r\n            <td data-label=\"Selection Warning\">\r\n              Confirm that the output can still drive the complete circuit\r\n              after SPD and cable resistance are included.\r\n            <\/td>\r\n          <\/tr>\r\n\r\n        <\/tbody>\r\n\r\n      <\/table>\r\n\r\n    <\/div>\r\n\r\n  <\/section>\r\n\r\n  <section class=\"ly24v-section\" id=\"ly24v-wiring\">\r\n\r\n    <div class=\"ly24v-section-head\">\r\n\r\n      <div class=\"ly24v-kicker\">\r\n        Sensor Wiring\r\n      <\/div>\r\n\r\n      <h2><span class=\"ez-toc-section\" id=\"two-three-and-four-wire-sensors-need-different-protection-paths\"><\/span>\r\n        Two-, Three- and Four-Wire Sensors Need Different Protection Paths\r\n      <span class=\"ez-toc-section-end\"><\/span><\/h2>\r\n\r\n      <p>\r\n        The conductor arrangement determines whether power and signal share the\r\n        same pair and how many external conductors need protection.\r\n      <\/p>\r\n\r\n    <\/div>\r\n\r\n    <div class=\"ly24v-wire-grid\">\r\n\r\n      <article class=\"ly24v-wire-card\">\r\n\r\n        <div class=\"ly24v-wire-title\">\r\n\r\n          <span class=\"ly24v-wire-number\">2<\/span>\r\n\r\n          <h3>\r\n            Two-Wire Transmitter\r\n          <\/h3>\r\n\r\n        <\/div>\r\n\r\n        <p>\r\n          A two-wire 4\u201320mA transmitter commonly uses the same conductor pair\r\n          for operating power and measured current.\r\n        <\/p>\r\n\r\n        <div class=\"ly24v-mini-lines\" aria-label=\"Two-wire loop\">\r\n\r\n          <div class=\"ly24v-mini-line\">\r\n            <span>Loop +<\/span>\r\n            <span>AI +<\/span>\r\n          <\/div>\r\n\r\n          <div class=\"ly24v-mini-line\">\r\n            <span>Loop \u2212<\/span>\r\n            <span>AI \u2212<\/span>\r\n          <\/div>\r\n\r\n        <\/div>\r\n\r\n        <ul>\r\n          <li>Confirm maximum loop voltage, not only nominal 24V.<\/li>\r\n          <li>Confirm added series resistance and loop-current capacity.<\/li>\r\n          <li>Confirm HART compatibility where communication is used.<\/li>\r\n        <\/ul>\r\n\r\n      <\/article>\r\n\r\n      <article class=\"ly24v-wire-card\">\r\n\r\n        <div class=\"ly24v-wire-title\">\r\n\r\n          <span class=\"ly24v-wire-number\">3<\/span>\r\n\r\n          <h3>\r\n            Three-Wire Sensor\r\n          <\/h3>\r\n\r\n        <\/div>\r\n\r\n        <p>\r\n          A common three-wire sensor has +24V, 0V and a separate digital or\r\n          analog output sharing the supply reference.\r\n        <\/p>\r\n\r\n        <div class=\"ly24v-mini-lines\" aria-label=\"Three-wire sensor\">\r\n\r\n          <div class=\"ly24v-mini-line\">\r\n            <span>+24V<\/span>\r\n            <span>Supply +<\/span>\r\n          <\/div>\r\n\r\n          <div class=\"ly24v-mini-line\">\r\n            <span>0V<\/span>\r\n            <span>Common<\/span>\r\n          <\/div>\r\n\r\n          <div class=\"ly24v-mini-line\">\r\n            <span>Signal<\/span>\r\n            <span>DI \/ AI<\/span>\r\n          <\/div>\r\n\r\n        <\/div>\r\n\r\n        <ul>\r\n          <li>Confirm PNP, NPN, sourcing or sinking operation.<\/li>\r\n          <li>Identify every conductor leaving the protected zone.<\/li>\r\n          <li>Do not assume that a two-wire loop SPD is sufficient.<\/li>\r\n        <\/ul>\r\n\r\n      <\/article>\r\n\r\n      <article class=\"ly24v-wire-card\">\r\n\r\n        <div class=\"ly24v-wire-title\">\r\n\r\n          <span class=\"ly24v-wire-number\">4<\/span>\r\n\r\n          <h3>\r\n            Four-Wire Instrument\r\n          <\/h3>\r\n\r\n        <\/div>\r\n\r\n        <p>\r\n          Power and signal can use separate pairs, requiring separate\r\n          protection functions or a coordinated multi-conductor solution.\r\n        <\/p>\r\n\r\n        <div class=\"ly24v-mini-lines\" aria-label=\"Four-wire instrument\">\r\n\r\n          <div class=\"ly24v-mini-line\">\r\n            <span>Power +<\/span>\r\n            <span>24V +<\/span>\r\n          <\/div>\r\n\r\n          <div class=\"ly24v-mini-line\">\r\n            <span>Power \u2212<\/span>\r\n            <span>24V 0V<\/span>\r\n          <\/div>\r\n\r\n          <div class=\"ly24v-mini-line\">\r\n            <span>Signal +<\/span>\r\n            <span>AI +<\/span>\r\n          <\/div>\r\n\r\n          <div class=\"ly24v-mini-line\">\r\n            <span>Signal \u2212<\/span>\r\n            <span>AI \u2212<\/span>\r\n          <\/div>\r\n\r\n        <\/div>\r\n\r\n        <ul>\r\n          <li>Separate power-pair and signal-pair requirements.<\/li>\r\n          <li>Confirm whether the signal pair is floating or referenced.<\/li>\r\n          <li>Confirm terminal count and protection modes before ordering.<\/li>\r\n        <\/ul>\r\n\r\n      <\/article>\r\n\r\n    <\/div>\r\n\r\n  <\/section>\r\n\r\n  <section class=\"ly24v-section\" id=\"ly24v-location\">\r\n\r\n    <div class=\"ly24v-section-head\">\r\n\r\n      <div class=\"ly24v-kicker\">\r\n        Installation Position\r\n      <\/div>\r\n\r\n      <h2><span class=\"ez-toc-section\" id=\"install-the-spd-at-the-field-end-cabinet-end-or-both-ends\"><\/span>\r\n        Install the SPD at the Field End, Cabinet End or Both Ends?\r\n      <span class=\"ez-toc-section-end\"><\/span><\/h2>\r\n\r\n      <p>\r\n        The installation position follows the cable exposure, protection-zone\r\n        boundary, equipment value and local bonding conditions.\r\n      <\/p>\r\n\r\n    <\/div>\r\n\r\n    <figure class=\"ly24v-figure\">\r\n\r\n      <img loading=\"lazy\"\r\n        src=\"https:\/\/www.cnspd.com\/wp-content\/uploads\/2026\/07\/24v-sensor-plc-io-surge-protection-architecture.webp\"\r\n        alt=\"24V sensor and PLC I\/O surge protection architecture showing SPDs at the field and control cabinet ends\"\r\n        width=\"1600\"\r\n        height=\"900\"\r\n        loading=\"lazy\"\r\n        decoding=\"async\"\r\n      >\r\n\r\n      <figcaption>\r\n        For a long or exposed field cable, coordinated protection may be\r\n        required near the field device and again at the control-cabinet entry\r\n        before the PLC I\/O module.\r\n      <\/figcaption>\r\n\r\n    <\/figure>\r\n\r\n    <div class=\"ly24v-table-wrap\">\r\n\r\n      <table class=\"ly24v-table ly24v-responsive-table\">\r\n\r\n        <thead>\r\n          <tr>\r\n            <th>Installation Scenario<\/th>\r\n            <th>Typical Protection Decision<\/th>\r\n            <th>Engineering Reason<\/th>\r\n          <\/tr>\r\n        <\/thead>\r\n\r\n        <tbody>\r\n\r\n          <tr>\r\n            <td data-label=\"Installation Scenario\">\r\n              <strong>Short wiring inside one cabinet<\/strong>\r\n            <\/td>\r\n\r\n            <td data-label=\"Typical Protection Decision\">\r\n              A dedicated signal SPD is often unnecessary unless a specific\r\n              internal transient risk has been identified.\r\n            <\/td>\r\n\r\n            <td data-label=\"Engineering Reason\">\r\n              The conductors do not cross an external protection boundary or a\r\n              separate grounding zone.\r\n            <\/td>\r\n          <\/tr>\r\n\r\n          <tr>\r\n            <td data-label=\"Installation Scenario\">\r\n              <strong>Indoor device in the same equipotential zone<\/strong>\r\n            <\/td>\r\n\r\n            <td data-label=\"Typical Protection Decision\">\r\n              Consider cabinet-entry protection when the cable is long,\r\n              exposed or operationally critical.\r\n            <\/td>\r\n\r\n            <td data-label=\"Engineering Reason\">\r\n              The PLC module is often the more sensitive and expensive\r\n              endpoint.\r\n            <\/td>\r\n          <\/tr>\r\n\r\n          <tr>\r\n            <td data-label=\"Installation Scenario\">\r\n              <strong>Outdoor sensor or transmitter<\/strong>\r\n            <\/td>\r\n\r\n            <td data-label=\"Typical Protection Decision\">\r\n              Consider coordinated SPDs near the field instrument and at the\r\n              cabinet entry.\r\n            <\/td>\r\n\r\n            <td data-label=\"Engineering Reason\">\r\n              Both endpoints can be exposed to transient voltage along the\r\n              field cable.\r\n            <\/td>\r\n          <\/tr>\r\n\r\n          <tr>\r\n            <td data-label=\"Installation Scenario\">\r\n              <strong>Cable between separate buildings<\/strong>\r\n            <\/td>\r\n\r\n            <td data-label=\"Typical Protection Decision\">\r\n              Protect both local endpoints and review bonding and shield\r\n              treatment.\r\n            <\/td>\r\n\r\n            <td data-label=\"Engineering Reason\">\r\n              Potential differences can occur between the two building\r\n              grounding systems.\r\n            <\/td>\r\n          <\/tr>\r\n\r\n          <tr>\r\n            <td data-label=\"Installation Scenario\">\r\n              <strong>Hazardous-area instrument loop<\/strong>\r\n            <\/td>\r\n\r\n            <td data-label=\"Typical Protection Decision\">\r\n              Use an appropriately approved SPD coordinated with the\r\n              intrinsic-safety design.\r\n            <\/td>\r\n\r\n            <td data-label=\"Engineering Reason\">\r\n              A general signal SPD must not be assumed suitable for an Ex i\r\n              circuit.\r\n            <\/td>\r\n          <\/tr>\r\n\r\n        <\/tbody>\r\n\r\n      <\/table>\r\n\r\n    <\/div>\r\n\r\n    <div class=\"ly24v-note\">\r\n\r\n      <strong>\r\n        Cabinet-entry rule\r\n      <\/strong>\r\n\r\n      <p>\r\n        Place the SPD where the external field cable enters the cabinet,\r\n        before the unprotected cable is routed through the PLC area. Keep the\r\n        incoming field conductors separated from the protected wiring leaving\r\n        the SPD. IEC 61643-22 addresses the selection, location and coordination\r\n        principles for signalling-network SPDs.<sup>[2]<\/sup>\r\n      <\/p>\r\n\r\n    <\/div>\r\n\r\n  <\/section>\r\n\r\n  <section class=\"ly24v-section\" id=\"ly24v-grounding\">\r\n\r\n    <div class=\"ly24v-section-head\">\r\n\r\n      <div class=\"ly24v-kicker\">\r\n        Bonding and EMC\r\n      <\/div>\r\n\r\n      <h2><span class=\"ez-toc-section\" id=\"grounding-and-shield-handling-for-a-24v-signal-spd\"><\/span>\r\n        Grounding and Shield Handling for a 24V Signal SPD\r\n      <span class=\"ez-toc-section-end\"><\/span><\/h2>\r\n\r\n      <p>\r\n        A suitable product can still deliver poor installed protection when\r\n        its discharge path is long or when protected and unprotected wiring\r\n        are routed together.\r\n      <\/p>\r\n\r\n    <\/div>\r\n\r\n    <div class=\"ly24v-check-grid\">\r\n\r\n      <div class=\"ly24v-check\">\r\n        <span class=\"ly24v-check-icon\">01<\/span>\r\n\r\n        <div>\r\n          <strong>Use a short local PE path<\/strong>\r\n\r\n          <p>\r\n            Connect the SPD to the cabinet PE or equipotential bonding\r\n            structure using the shortest practical route.\r\n          <\/p>\r\n        <\/div>\r\n      <\/div>\r\n\r\n      <div class=\"ly24v-check\">\r\n        <span class=\"ly24v-check-icon\">02<\/span>\r\n\r\n        <div>\r\n          <strong>Check DIN-rail bonding<\/strong>\r\n\r\n          <p>\r\n            When the SPD uses the mounting rail as part of its PE connection,\r\n            the rail must be reliably bonded to the cabinet PE structure.\r\n          <\/p>\r\n        <\/div>\r\n      <\/div>\r\n\r\n      <div class=\"ly24v-check\">\r\n        <span class=\"ly24v-check-icon\">03<\/span>\r\n\r\n        <div>\r\n          <strong>Separate line and protected sides<\/strong>\r\n\r\n          <p>\r\n            Do not route incoming field wiring beside the protected conductors\r\n            after the SPD.\r\n          <\/p>\r\n        <\/div>\r\n      <\/div>\r\n\r\n      <div class=\"ly24v-check\">\r\n        <span class=\"ly24v-check-icon\">04<\/span>\r\n\r\n        <div>\r\n          <strong>Do not use the shield as the only PE path<\/strong>\r\n\r\n          <p>\r\n            The cable shield performs an EMC function and should not replace\r\n            the SPD grounding connection.\r\n          <\/p>\r\n        <\/div>\r\n      <\/div>\r\n\r\n      <div class=\"ly24v-check\">\r\n        <span class=\"ly24v-check-icon\">05<\/span>\r\n\r\n        <div>\r\n          <strong>Confirm the circuit reference<\/strong>\r\n\r\n          <p>\r\n            Floating analog pairs and common-reference digital circuits can\r\n            require different protection arrangements.\r\n          <\/p>\r\n        <\/div>\r\n      <\/div>\r\n\r\n      <div class=\"ly24v-check\">\r\n        <span class=\"ly24v-check-icon\">06<\/span>\r\n\r\n        <div>\r\n          <strong>Coordinate shield termination<\/strong>\r\n\r\n          <p>\r\n            Single-ended or multi-point shield bonding depends on the EMC\r\n            design and equipotential conditions, not one universal rule.\r\n          <\/p>\r\n        <\/div>\r\n      <\/div>\r\n\r\n    <\/div>\r\n\r\n  <\/section>\r\n\r\n  <section class=\"ly24v-section\" id=\"ly24v-parameters\">\r\n\r\n    <div class=\"ly24v-section-head\">\r\n\r\n      <div class=\"ly24v-kicker\">\r\n        Technical Selection\r\n      <\/div>\r\n\r\n      <h2><span class=\"ez-toc-section\" id=\"parameters-to-confirm-before-choosing-the-spd\"><\/span>\r\n        Parameters to Confirm Before Choosing the SPD\r\n      <span class=\"ez-toc-section-end\"><\/span><\/h2>\r\n\r\n      <p>\r\n        These parameters determine whether the protector can survive normal\r\n        operation and protect the port without distorting the signal.\r\n      <\/p>\r\n\r\n    <\/div>\r\n\r\n    <div class=\"ly24v-check-grid\">\r\n\r\n      <div class=\"ly24v-check\">\r\n        <span class=\"ly24v-check-icon\">01<\/span>\r\n\r\n        <div>\r\n          <strong>Nominal and maximum operating voltage<\/strong>\r\n\r\n          <p>\r\n            State the normal voltage and the highest expected value, including\r\n            power-supply tolerance.\r\n          <\/p>\r\n        <\/div>\r\n      <\/div>\r\n\r\n      <div class=\"ly24v-check\">\r\n        <span class=\"ly24v-check-icon\">02<\/span>\r\n\r\n        <div>\r\n          <strong>Signal and PLC I\/O type<\/strong>\r\n\r\n          <p>\r\n            Identify DI, DO, AI, AO, 4\u201320mA, 0\u201310V, PNP, NPN or another\r\n            defined interface.\r\n          <\/p>\r\n        <\/div>\r\n      <\/div>\r\n\r\n      <div class=\"ly24v-check\">\r\n        <span class=\"ly24v-check-icon\">03<\/span>\r\n\r\n        <div>\r\n          <strong>Circuit topology<\/strong>\r\n\r\n          <p>\r\n            Confirm floating pair, common reference and required line-to-line\r\n            and line-to-earth protection modes.\r\n          <\/p>\r\n        <\/div>\r\n      <\/div>\r\n\r\n      <div class=\"ly24v-check\">\r\n        <span class=\"ly24v-check-icon\">04<\/span>\r\n\r\n        <div>\r\n          <strong>Maximum operating current<\/strong>\r\n\r\n          <p>\r\n            The SPD must carry the loop or load current without excessive\r\n            heating or voltage drop.\r\n          <\/p>\r\n        <\/div>\r\n      <\/div>\r\n\r\n      <div class=\"ly24v-check\">\r\n        <span class=\"ly24v-check-icon\">05<\/span>\r\n\r\n        <div>\r\n          <strong>Series resistance<\/strong>\r\n\r\n          <p>\r\n            Include the SPD resistance in the complete analog-loop burden and\r\n            voltage-margin calculation.\r\n          <\/p>\r\n        <\/div>\r\n      <\/div>\r\n\r\n      <div class=\"ly24v-check\">\r\n        <span class=\"ly24v-check-icon\">06<\/span>\r\n\r\n        <div>\r\n          <strong>Leakage current<\/strong>\r\n\r\n          <p>\r\n            Excess leakage can affect a PLC input threshold or introduce error\r\n            in a sensitive analog circuit.\r\n          <\/p>\r\n        <\/div>\r\n      <\/div>\r\n\r\n      <div class=\"ly24v-check\">\r\n        <span class=\"ly24v-check-icon\">07<\/span>\r\n\r\n        <div>\r\n          <strong>Voltage protection or limiting level<\/strong>\r\n\r\n          <p>\r\n            Compare the SPD limiting voltage with the withstand capability of\r\n            the PLC or field device.\r\n          <\/p>\r\n        <\/div>\r\n      <\/div>\r\n\r\n      <div class=\"ly24v-check\">\r\n        <span class=\"ly24v-check-icon\">08<\/span>\r\n\r\n        <div>\r\n          <strong>Capacitance, bandwidth or HART<\/strong>\r\n\r\n          <p>\r\n            Confirm that the SPD will not attenuate or distort the required\r\n            signal or superimposed communication.\r\n          <\/p>\r\n        <\/div>\r\n      <\/div>\r\n\r\n      <div class=\"ly24v-check\">\r\n        <span class=\"ly24v-check-icon\">09<\/span>\r\n\r\n        <div>\r\n          <strong>Conductors, channels and terminals<\/strong>\r\n\r\n          <p>\r\n            Confirm two-, three- or four-wire construction, common terminals\r\n            and channels per module.\r\n          <\/p>\r\n        <\/div>\r\n      <\/div>\r\n\r\n      <div class=\"ly24v-check\">\r\n        <span class=\"ly24v-check-icon\">10<\/span>\r\n\r\n        <div>\r\n          <strong>Environment and approval<\/strong>\r\n\r\n          <p>\r\n            Confirm operating temperature, mounting, enclosure, hazardous-area\r\n            status and required standards documentation.\r\n          <\/p>\r\n        <\/div>\r\n      <\/div>\r\n\r\n    <\/div>\r\n\r\n    <div class=\"ly24v-warning\">\r\n\r\n      <strong>\r\n        Do not compare products by kA rating alone.\r\n      <\/strong>\r\n\r\n      <p>\r\n        A larger discharge-current value does not automatically make a product\r\n        better for a PLC or sensor port. The test waveform, protection mode,\r\n        limiting voltage and signal characteristics must also be known.\r\n      <\/p>\r\n\r\n    <\/div>\r\n\r\n  <\/section>\r\n\r\n  <section class=\"ly24v-section\" id=\"ly24v-examples\">\r\n\r\n    <div class=\"ly24v-section-head\">\r\n\r\n      <div class=\"ly24v-kicker\">\r\n        Application Examples\r\n      <\/div>\r\n\r\n      <h2><span class=\"ez-toc-section\" id=\"practical-24v-sensor-and-plc-io-selection-examples\"><\/span>\r\n        Practical 24V Sensor and PLC I\/O Selection Examples\r\n      <span class=\"ez-toc-section-end\"><\/span><\/h2>\r\n\r\n      <p>\r\n        These examples show why circuits with the same nominal 24V voltage can\r\n        require different SPDs.\r\n      <\/p>\r\n\r\n    <\/div>\r\n\r\n    <div class=\"ly24v-example-grid\">\r\n\r\n      <article class=\"ly24v-example\">\r\n\r\n        <span class=\"ly24v-example-label\">\r\n          Example A\r\n        <\/span>\r\n\r\n        <h3>\r\n          Outdoor Two-Wire 4\u201320mA Transmitter\r\n        <\/h3>\r\n\r\n        <ul>\r\n          <li>Protect the complete current-loop pair.<\/li>\r\n          <li>Confirm the highest loop voltage and maximum loop current.<\/li>\r\n          <li>\r\n            Add the SPD resistance to cable and PLC input burden calculations.\r\n          <\/li>\r\n          <li>Confirm HART compatibility where required.<\/li>\r\n          <li>\r\n            Consider coordinated protection at both ends of an exposed cable.\r\n          <\/li>\r\n        <\/ul>\r\n\r\n      <\/article>\r\n\r\n      <article class=\"ly24v-example\">\r\n\r\n        <span class=\"ly24v-example-label\">\r\n          Example B\r\n        <\/span>\r\n\r\n        <h3>\r\n          Three-Wire PNP Sensor Connected to PLC DI\r\n        <\/h3>\r\n\r\n        <ul>\r\n          <li>Identify +24V, 0V and the switching-output conductor.<\/li>\r\n          <li>Confirm the common-reference protection arrangement.<\/li>\r\n          <li>Check leakage against the PLC input threshold.<\/li>\r\n          <li>Protect the required external conductors.<\/li>\r\n          <li>Install the SPD at the control-cabinet cable entry.<\/li>\r\n        <\/ul>\r\n\r\n      <\/article>\r\n\r\n      <article class=\"ly24v-example\">\r\n\r\n        <span class=\"ly24v-example-label\">\r\n          Example C\r\n        <\/span>\r\n\r\n        <h3>\r\n          PLC DO Controlling an Outdoor Solenoid\r\n        <\/h3>\r\n\r\n        <ul>\r\n          <li>Confirm output type, polarity and load current.<\/li>\r\n          <li>Protect the long external cable at the cabinet boundary.<\/li>\r\n          <li>Provide suitable local suppression for the inductive coil.<\/li>\r\n          <li>\r\n            Do not expect the surge SPD to replace repetitive-switching\r\n            suppression.\r\n          <\/li>\r\n        <\/ul>\r\n\r\n      <\/article>\r\n\r\n      <article class=\"ly24v-example\">\r\n\r\n        <span class=\"ly24v-example-label\">\r\n          Example D\r\n        <\/span>\r\n\r\n        <h3>\r\n          0\u201310V Sensor Connected to PLC AI\r\n        <\/h3>\r\n\r\n        <ul>\r\n          <li>Confirm maximum signal voltage and reference topology.<\/li>\r\n          <li>Prioritize low leakage and low added signal error.<\/li>\r\n          <li>Check series resistance and capacitance.<\/li>\r\n          <li>Separate protected and unprotected wiring.<\/li>\r\n          <li>Do not substitute a general 24V power SPD.<\/li>\r\n        <\/ul>\r\n\r\n      <\/article>\r\n\r\n    <\/div>\r\n\r\n  <\/section>\r\n\r\n  <section\r\n    class=\"ly24v-section ly24v-product-boundary\"\r\n    id=\"ly24v-product-boundary\"\r\n  >\r\n\r\n    <div class=\"ly24v-product-main\">\r\n\r\n      <div class=\"ly24v-kicker\">\r\n        Product Application Boundary\r\n      <\/div>\r\n\r\n      <h2><span class=\"ez-toc-section\" id=\"where-ly10-fits%e2%80%94and-where-separate-confirmation-is-required\"><\/span>\r\n        Where LY10 Fits\u2014and Where Separate Confirmation Is Required\r\n      <span class=\"ez-toc-section-end\"><\/span><\/h2>\r\n\r\n      <p>\r\n        LEEYEE LY10 is publicly presented as a DIN-rail data signal surge\r\n        protector for RS485, telemetry, remote-control, PLC, sensor and\r\n        industrial communication lines. The available range includes 12V,\r\n        24V and 48V signal-system versions.\r\n      <\/p>\r\n\r\n      <p>\r\n        This does not automatically prove that one LY10 version is suitable\r\n        for every 4\u201320mA, 0\u201310V, AI, AO or three-wire sensor circuit.\r\n        Compatibility must be confirmed against the complete electrical\r\n        parameters of the real loop.\r\n      <\/p>\r\n\r\n      <div class=\"ly24v-product-columns\">\r\n\r\n        <article class=\"ly24v-product-card is-confirmed\">\r\n\r\n          <h3>\r\n            Publicly Confirmed Product Direction\r\n          <\/h3>\r\n\r\n          <ul>\r\n            <li>RS485 and industrial communication lines<\/li>\r\n            <li>Telemetry and remote-control signals<\/li>\r\n            <li>12V, 24V and 48V signal-system versions<\/li>\r\n            <li>DIN-rail series installation<\/li>\r\n            <li>Rated load current listed as 500mA<\/li>\r\n            <li>Transmission rate listed up to 10Mbps<\/li>\r\n            <li>Insertion loss listed as no more than 0.2dB<\/li>\r\n          <\/ul>\r\n\r\n        <\/article>\r\n\r\n        <article class=\"ly24v-product-card is-review\">\r\n\r\n          <h3>\r\n            Applications Requiring Additional Confirmation\r\n          <\/h3>\r\n\r\n          <ul>\r\n            <li>Two-wire 4\u201320mA transmitter loops<\/li>\r\n            <li>0\u201310V analog inputs and outputs<\/li>\r\n            <li>HART-enabled analog loops<\/li>\r\n            <li>Three-wire PNP or NPN sensors<\/li>\r\n            <li>PLC outputs carrying external load current<\/li>\r\n            <li>Circuits with strict resistance or leakage limits<\/li>\r\n            <li>Hazardous-area or intrinsically safe loops<\/li>\r\n          <\/ul>\r\n\r\n        <\/article>\r\n\r\n      <\/div>\r\n\r\n      <div class=\"ly24v-button-row\">\r\n\r\n        <a\r\n          href=\"https:\/\/www.cnspd.com\/portfolio\/ly10-data-signal-dc-surge-protective-device\/\"\r\n          class=\"ly24v-btn ly24v-btn-outline\"\r\n          target=\"_blank\"\r\n          rel=\"noopener\"\r\n        >\r\n          <span>View LY10 Signal SPD<\/span>\r\n        <\/a>\r\n\r\n        <a\r\n          href=\"javascript:void(0);\"\r\n          class=\"ly24v-btn leeyee-site-popup-btn\"\r\n          aria-label=\"Request 24V signal SPD model confirmation\"\r\n        >\r\n          <span>Request Model Confirmation<\/span>\r\n        <\/a>\r\n\r\n      <\/div>\r\n\r\n    <\/div>\r\n\r\n    <aside class=\"ly24v-product-side\">\r\n\r\n      <h3>\r\n        Send the Real Circuit Before Ordering\r\n      <\/h3>\r\n\r\n      <p>\r\n        A wiring diagram allows LEEYEE to determine whether an existing\r\n        signal-SPD model can be used or whether another configuration is\r\n        required.\r\n      <\/p>\r\n\r\n      <ul>\r\n        <li>PLC I\/O module model<\/li>\r\n        <li>DI, DO, AI or AO<\/li>\r\n        <li>4\u201320mA, 0\u201310V, PNP, NPN or data signal<\/li>\r\n        <li>Maximum circuit voltage and current<\/li>\r\n        <li>Two-, three- or four-wire device<\/li>\r\n        <li>Cable length and installation environment<\/li>\r\n        <li>Grounding and shield arrangement<\/li>\r\n      <\/ul>\r\n\r\n      <a\r\n        href=\"javascript:void(0);\"\r\n        class=\"ly24v-btn ly24v-btn-light leeyee-site-popup-btn\"\r\n        aria-label=\"Ask LEEYEE to review a 24V signal circuit\"\r\n      >\r\n        <span>Ask LEEYEE to Review the Circuit<\/span>\r\n      <\/a>\r\n\r\n    <\/aside>\r\n\r\n  <\/section>\r\n\r\n  <section class=\"ly24v-section\">\r\n\r\n    <div class=\"ly24v-section-head\">\r\n\r\n      <div class=\"ly24v-kicker\">\r\n        Avoid Wrong Orders\r\n      <\/div>\r\n\r\n      <h2><span class=\"ez-toc-section\" id=\"common-selection-and-installation-mistakes\"><\/span>\r\n        Common Selection and Installation Mistakes\r\n      <span class=\"ez-toc-section-end\"><\/span><\/h2>\r\n\r\n    <\/div>\r\n\r\n    <div class=\"ly24v-mistake-grid\">\r\n\r\n      <div class=\"ly24v-mistake\">\r\n        <span class=\"ly24v-mistake-icon\">\u00d7<\/span>\r\n\r\n        <div>\r\n          <strong>Buying a power SPD because it says 24V<\/strong>\r\n\r\n          <p>\r\n            A 24V power protector is not automatically suitable for an analog\r\n            or digital PLC signal circuit.\r\n          <\/p>\r\n        <\/div>\r\n      <\/div>\r\n\r\n      <div class=\"ly24v-mistake\">\r\n        <span class=\"ly24v-mistake-icon\">\u00d7<\/span>\r\n\r\n        <div>\r\n          <strong>Using one model for every I\/O function<\/strong>\r\n\r\n          <p>\r\n            DI, DO, AI and AO can have different current, reference and\r\n            signal-integrity requirements.\r\n          <\/p>\r\n        <\/div>\r\n      <\/div>\r\n\r\n      <div class=\"ly24v-mistake\">\r\n        <span class=\"ly24v-mistake-icon\">\u00d7<\/span>\r\n\r\n        <div>\r\n          <strong>Ignoring PNP or NPN wiring<\/strong>\r\n\r\n          <p>\r\n            Incorrect assumptions about sourcing, sinking and the common\r\n            conductor can produce the wrong terminal arrangement.\r\n          <\/p>\r\n        <\/div>\r\n      <\/div>\r\n\r\n      <div class=\"ly24v-mistake\">\r\n        <span class=\"ly24v-mistake-icon\">\u00d7<\/span>\r\n\r\n        <div>\r\n          <strong>Ignoring analog-loop resistance<\/strong>\r\n\r\n          <p>\r\n            Added resistance can reduce available loop voltage or affect\r\n            measurement performance.\r\n          <\/p>\r\n        <\/div>\r\n      <\/div>\r\n\r\n      <div class=\"ly24v-mistake\">\r\n        <span class=\"ly24v-mistake-icon\">\u00d7<\/span>\r\n\r\n        <div>\r\n          <strong>Installing the SPD deep inside the cabinet<\/strong>\r\n\r\n          <p>\r\n            Unprotected field wiring should not travel through the sensitive\r\n            PLC area before reaching the SPD.\r\n          <\/p>\r\n        <\/div>\r\n      <\/div>\r\n\r\n      <div class=\"ly24v-mistake\">\r\n        <span class=\"ly24v-mistake-icon\">\u00d7<\/span>\r\n\r\n        <div>\r\n          <strong>Comparing products by kA alone<\/strong>\r\n\r\n          <p>\r\n            The waveform, protection mode, limiting voltage and signal\r\n            parameters are also required for a meaningful comparison.\r\n          <\/p>\r\n        <\/div>\r\n      <\/div>\r\n\r\n    <\/div>\r\n\r\n  <\/section>\r\n\r\n  <section class=\"ly24v-section\" id=\"ly24v-ordering\">\r\n\r\n    <div class=\"ly24v-section-head\">\r\n\r\n      <div class=\"ly24v-kicker\">\r\n        Procurement Checklist\r\n      <\/div>\r\n\r\n      <h2><span class=\"ez-toc-section\" id=\"what-an-oem-buyer-or-panel-builder-should-confirm\"><\/span>\r\n        What an OEM Buyer or Panel Builder Should Confirm\r\n      <span class=\"ez-toc-section-end\"><\/span><\/h2>\r\n\r\n      <p>\r\n        Provide enough circuit information to prevent model, terminal,\r\n        labelling and sampling errors.\r\n      <\/p>\r\n\r\n    <\/div>\r\n\r\n    <figure class=\"ly24v-figure\">\r\n\r\n      <img loading=\"lazy\"\r\n        src=\"https:\/\/www.cnspd.com\/wp-content\/uploads\/2026\/07\/24v-signal-spd-oem-ordering-checklist.webp\"\r\n        alt=\"OEM ordering checklist for 24V sensor and PLC I\/O signal surge protectors\"\r\n        width=\"1600\"\r\n        height=\"900\"\r\n        loading=\"lazy\"\r\n        decoding=\"async\"\r\n      >\r\n\r\n      <figcaption>\r\n        Confirm the voltage, I\/O function, signal format, sensor wiring,\r\n        electrical performance, mounting, terminals and required documentation\r\n        before approving the model.\r\n      <\/figcaption>\r\n\r\n    <\/figure>\r\n\r\n    <div class=\"ly24v-order-box\">\r\n\r\n      <div class=\"ly24v-order-main\">\r\n\r\n        <h3>\r\n          Technical and Commercial Confirmation List\r\n        <\/h3>\r\n\r\n        <ul class=\"ly24v-order-list\">\r\n          <li>Nominal and maximum circuit voltage<\/li>\r\n          <li>DI, DO, AI or AO function<\/li>\r\n          <li>4\u201320mA, 0\u201310V, PNP, NPN or data signal<\/li>\r\n          <li>Two-, three- or four-wire circuit<\/li>\r\n          <li>Floating or common-reference topology<\/li>\r\n          <li>Maximum loop or load current<\/li>\r\n          <li>Permissible resistance, leakage and signal error<\/li>\r\n          <li>Conductors, channels and terminal numbering<\/li>\r\n          <li>DIN-rail, cabinet or field mounting<\/li>\r\n          <li>Temperature, hazardous-area and approval requirements<\/li>\r\n          <li>OEM logo, label and packaging requirements<\/li>\r\n          <li>Sample quantity and estimated annual volume<\/li>\r\n        <\/ul>\r\n\r\n      <\/div>\r\n\r\n      <aside class=\"ly24v-order-side\">\r\n\r\n        <h3>\r\n          Best RFQ Attachment\r\n        <\/h3>\r\n\r\n        <p>\r\n          Send the PLC I\/O list, field wiring diagram and one marked-up cabinet\r\n          drawing. These documents provide more useful information than a\r\n          request stating only \u201c24V SPD required.\u201d\r\n        <\/p>\r\n\r\n        <a\r\n          href=\"javascript:void(0);\"\r\n          class=\"ly24v-btn leeyee-site-popup-btn\"\r\n          aria-label=\"Send 24V signal SPD requirements\"\r\n        >\r\n          <span>Send Your Requirements<\/span>\r\n        <\/a>\r\n\r\n      <\/aside>\r\n\r\n    <\/div>\r\n\r\n  <\/section>\r\n\r\n  <section class=\"ly24v-section\" id=\"ly24v-faq\">\r\n\r\n    <div class=\"ly24v-section-head\">\r\n\r\n      <div class=\"ly24v-kicker\">\r\n        FAQ\r\n      <\/div>\r\n\r\n      <h2><span class=\"ez-toc-section\" id=\"24v-signal-surge-protector-faq\"><\/span>\r\n        24V Signal Surge Protector FAQ\r\n      <span class=\"ez-toc-section-end\"><\/span><\/h2>\r\n\r\n    <\/div>\r\n\r\n    <div class=\"ly24v-faq-list\">\r\n\r\n      <details class=\"ly24v-faq\">\r\n\r\n        <summary>\r\n          Does every 24V sensor need a surge protector?\r\n        <\/summary>\r\n\r\n        <div class=\"ly24v-faq-answer\">\r\n          <p>\r\n            No. Short wiring located completely inside one cabinet may not need\r\n            an individual signal SPD. Protection becomes more important for\r\n            outdoor devices, long cables, cross-building wiring, separate\r\n            grounding zones and systems where downtime is costly.\r\n          <\/p>\r\n        <\/div>\r\n\r\n      <\/details>\r\n\r\n      <details class=\"ly24v-faq\">\r\n\r\n        <summary>\r\n          Can one 24V SPD protect DI, DO, AI and AO?\r\n        <\/summary>\r\n\r\n        <div class=\"ly24v-faq-answer\">\r\n          <p>\r\n            Not automatically. Digital and analog circuits can have different\r\n            topology, current, leakage, resistance, capacitance and\r\n            signal-integrity requirements. Confirm the exact I\/O function\r\n            before selecting the model.\r\n          <\/p>\r\n        <\/div>\r\n\r\n      <\/details>\r\n\r\n      <details class=\"ly24v-faq\">\r\n\r\n        <summary>\r\n          Can a 24V DC power SPD protect a 4\u201320mA loop?\r\n        <\/summary>\r\n\r\n        <div class=\"ly24v-faq-answer\">\r\n          <p>\r\n            It should not be assumed. A 4\u201320mA loop requires a signal protector\r\n            selected for the loop voltage, current, resistance, leakage,\r\n            limiting voltage and communication requirements.\r\n          <\/p>\r\n        <\/div>\r\n\r\n      <\/details>\r\n\r\n      <details class=\"ly24v-faq\">\r\n\r\n        <summary>\r\n          Will an SPD affect a 4\u201320mA measurement?\r\n        <\/summary>\r\n\r\n        <div class=\"ly24v-faq-answer\">\r\n          <p>\r\n            It can when its series resistance or leakage current is unsuitable.\r\n            Include the SPD resistance in the transmitter, cable and PLC input\r\n            burden calculation and verify that adequate loop-voltage margin\r\n            remains.\r\n          <\/p>\r\n        <\/div>\r\n\r\n      <\/details>\r\n\r\n      <details class=\"ly24v-faq\">\r\n\r\n        <summary>\r\n          Where should the SPD be installed in a PLC cabinet?\r\n        <\/summary>\r\n\r\n        <div class=\"ly24v-faq-answer\">\r\n          <p>\r\n            Install it at the external cable-entry boundary before the field\r\n            wiring reaches the PLC I\/O terminals. Keep the PE connection short\r\n            and separate incoming field wiring from the protected side.\r\n          <\/p>\r\n        <\/div>\r\n\r\n      <\/details>\r\n\r\n      <details class=\"ly24v-faq\">\r\n\r\n        <summary>\r\n          Is LY10 suitable for every 24V PLC I\/O circuit?\r\n        <\/summary>\r\n\r\n        <div class=\"ly24v-faq-answer\">\r\n          <p>\r\n            No universal suitability should be assumed. LY10 is publicly\r\n            positioned for RS485 and compatible industrial communication\r\n            lines. A 4\u201320mA, 0\u201310V, AI, AO, PNP or NPN circuit requires\r\n            confirmation against the actual electrical parameters.\r\n          <\/p>\r\n        <\/div>\r\n\r\n      <\/details>\r\n\r\n    <\/div>\r\n\r\n  <\/section>\r\n\r\n  <section class=\"ly24v-section\">\r\n\r\n    <div class=\"ly24v-section-head\">\r\n\r\n      <div class=\"ly24v-kicker\">\r\n        Related Technical Guides\r\n      <\/div>\r\n\r\n      <h2><span class=\"ez-toc-section\" id=\"keep-each-protection-topic-separate\"><\/span>\r\n        Keep Each Protection Topic Separate\r\n      <span class=\"ez-toc-section-end\"><\/span><\/h2>\r\n\r\n      <p>\r\n        Use this page for 24V sensor and PLC I\/O signals. Use the related guides\r\n        for complete control-panel architecture and RS485 communication wiring.\r\n      <\/p>\r\n\r\n    <\/div>\r\n\r\n    <div class=\"ly24v-related\">\r\n\r\n      <a\r\n        href=\"https:\/\/www.cnspd.com\/surge-protection-for-industrial-control-panels\/\"\r\n        target=\"_blank\"\r\n        rel=\"noopener\"\r\n      >\r\n        Surge Protection for Industrial Control Panels\r\n\r\n        <span>\r\n          AC input, 24V power, PLC, VFD, relay and field-wiring protection at\r\n          panel level.\r\n        <\/span>\r\n      <\/a>\r\n\r\n      <a\r\n        href=\"https:\/\/www.cnspd.com\/rs485-spd-wiring-selection\/\"\r\n        target=\"_blank\"\r\n        rel=\"noopener\"\r\n      >\r\n        RS485 SPD Wiring and Selection Guide\r\n\r\n        <span>\r\n          A\/B conductors, shield, baud rate, cabinet entry and industrial\r\n          communication protection.\r\n        <\/span>\r\n      <\/a>\r\n\r\n      <a\r\n        href=\"https:\/\/www.cnspd.com\/portfolio\/ly10-data-signal-dc-surge-protective-device\/\"\r\n        target=\"_blank\"\r\n        rel=\"noopener\"\r\n      >\r\n        LY10 Data Signal Surge Protector\r\n\r\n        <span>\r\n          DIN-rail product direction for RS485, telemetry, remote-control and\r\n          industrial communication lines.\r\n        <\/span>\r\n      <\/a>\r\n\r\n    <\/div>\r\n\r\n  <\/section>\r\n\r\n  <section class=\"ly24v-section ly24v-references\">\r\n\r\n    <h2><span class=\"ez-toc-section\" id=\"technical-references\"><\/span>\r\n      Technical References\r\n    <span class=\"ez-toc-section-end\"><\/span><\/h2>\r\n\r\n    <ol>\r\n\r\n      <li>\r\n        IEC 61643-21:2025, surge protective devices connected to\r\n        telecommunications and signalling networks\u2014requirements and test\r\n        methods.\r\n        <a\r\n          href=\"https:\/\/webstore.iec.ch\/en\/publication\/69085\"\r\n          target=\"_blank\"\r\n          rel=\"noopener nofollow\"\r\n        >\r\n          IEC publication page\r\n        <\/a>.\r\n      <\/li>\r\n\r\n      <li>\r\n        IEC 61643-22:2015, selection, operation, location and coordination\r\n        principles for SPDs connected to telecommunications and signalling\r\n        networks.\r\n        <a\r\n          href=\"https:\/\/webstore.iec.ch\/en\/publication\/22772\"\r\n          target=\"_blank\"\r\n          rel=\"noopener nofollow\"\r\n        >\r\n          IEC publication page\r\n        <\/a>.\r\n      <\/li>\r\n\r\n      <li>\r\n        IEC 61000-4-5:2014+A1:2017, electromagnetic compatibility surge\r\n        immunity testing and measurement techniques.\r\n        <a\r\n          href=\"https:\/\/webstore.iec.ch\/en\/publication\/61166\"\r\n          target=\"_blank\"\r\n          rel=\"noopener nofollow\"\r\n        >\r\n          IEC publication page\r\n        <\/a>.\r\n      <\/li>\r\n\r\n      <li>\r\n        Phoenix Contact, surge protection for measurement, control and signal\r\n        technology, including analog and common-reference signal circuits.\r\n        <a\r\n          href=\"https:\/\/www.phoenixcontact.com\/en-pc\/products\/surge-protection\/surge-protection-for-mcr-technology-and-signals\"\r\n          target=\"_blank\"\r\n          rel=\"noopener nofollow\"\r\n        >\r\n          Phoenix Contact technical page\r\n        <\/a>.\r\n      <\/li>\r\n\r\n      <li>\r\n        Weidm\u00fcller, surge protection for instrumentation and control circuits,\r\n        including analog and binary signals.\r\n        <a\r\n          href=\"https:\/\/www.weidmuller.com.sg\/en\/products\/electronics\/lightning_and_surge_protection\/surge_protection_for_instrumentation_and_control_%28i_c%29.jsp\"\r\n          target=\"_blank\"\r\n          rel=\"noopener nofollow\"\r\n        >\r\n          Weidm\u00fcller technical page\r\n        <\/a>.\r\n      <\/li>\r\n\r\n      <li>\r\n        LEEYEE LY10 DIN-rail data signal surge protector product information.\r\n        <a\r\n          href=\"https:\/\/www.cnspd.com\/portfolio\/ly10-data-signal-dc-surge-protective-device\/\"\r\n          target=\"_blank\"\r\n          rel=\"noopener\"\r\n        >\r\n          LEEYEE product page\r\n        <\/a>.\r\n      <\/li>\r\n\r\n    <\/ol>\r\n\r\n  <\/section>\r\n\r\n  <section class=\"ly24v-final-cta\">\r\n\r\n    <h2><span class=\"ez-toc-section\" id=\"need-a-24v-signal-spd-for-a-real-plc-io-circuit\"><\/span>\r\n      Need a 24V Signal SPD for a Real PLC I\/O Circuit?\r\n    <span class=\"ez-toc-section-end\"><\/span><\/h2>\r\n\r\n    <p>\r\n      Send the PLC I\/O list, sensor wiring, maximum circuit voltage, loop or\r\n      load current, cable length and grounding arrangement. LEEYEE will first\r\n      separate power, digital I\/O, analog-loop and communication requirements\r\n      before confirming a model.\r\n    <\/p>\r\n\r\n    <div class=\"ly24v-button-row\">\r\n\r\n      <a\r\n        href=\"javascript:void(0);\"\r\n        class=\"ly24v-btn ly24v-btn-light leeyee-site-popup-btn\"\r\n        aria-label=\"Request a 24V signal SPD recommendation\"\r\n      >\r\n        <span>Request a 24V Signal SPD Recommendation<\/span>\r\n      <\/a>\r\n\r\n    <\/div>\r\n\r\n  <\/section>\r\n\r\n<\/article>\r\n\r\n<script type=\"application\/ld+json\">\r\n{\r\n  \"@context\": \"https:\/\/schema.org\",\r\n  \"@type\": \"FAQPage\",\r\n  \"mainEntity\": [\r\n    {\r\n      \"@type\": \"Question\",\r\n      \"name\": \"Does every 24V sensor need a surge protector?\",\r\n      \"acceptedAnswer\": {\r\n        \"@type\": \"Answer\",\r\n        \"text\": \"No. Short wiring located completely inside one cabinet may not need an individual signal SPD. Protection becomes more important for outdoor devices, long cables, cross-building wiring, separate grounding zones and systems where downtime is costly.\"\r\n      }\r\n    },\r\n    {\r\n      \"@type\": \"Question\",\r\n      \"name\": \"Can one 24V SPD protect DI, DO, AI and AO?\",\r\n      \"acceptedAnswer\": {\r\n        \"@type\": \"Answer\",\r\n        \"text\": \"Not automatically. Digital and analog circuits can have different topology, current, leakage, resistance, capacitance and signal-integrity requirements. Confirm the exact I\/O function before selecting the model.\"\r\n      }\r\n    },\r\n    {\r\n      \"@type\": \"Question\",\r\n      \"name\": \"Can a 24V DC power SPD protect a 4-20mA loop?\",\r\n      \"acceptedAnswer\": {\r\n        \"@type\": \"Answer\",\r\n        \"text\": \"It should not be assumed. A 4-20mA loop requires a signal protector selected for the loop voltage, current, resistance, leakage, limiting voltage and communication requirements.\"\r\n      }\r\n    },\r\n    {\r\n      \"@type\": \"Question\",\r\n      \"name\": \"Will an SPD affect a 4-20mA measurement?\",\r\n      \"acceptedAnswer\": {\r\n        \"@type\": \"Answer\",\r\n        \"text\": \"It can when its series resistance or leakage current is unsuitable. Include the SPD resistance in the transmitter, cable and PLC input burden calculation and verify that adequate loop-voltage margin remains.\"\r\n      }\r\n    },\r\n    {\r\n      \"@type\": \"Question\",\r\n      \"name\": \"Where should the SPD be installed in a PLC cabinet?\",\r\n      \"acceptedAnswer\": {\r\n        \"@type\": \"Answer\",\r\n        \"text\": \"Install it at the external cable-entry boundary before the field wiring reaches the PLC I\/O terminals. Keep the PE connection short and separate incoming field wiring from the protected side.\"\r\n      }\r\n    },\r\n    {\r\n      \"@type\": \"Question\",\r\n      \"name\": \"Is LY10 suitable for every 24V PLC I\/O circuit?\",\r\n      \"acceptedAnswer\": {\r\n        \"@type\": \"Answer\",\r\n        \"text\": \"No universal suitability should be assumed. LY10 is publicly positioned for RS485 and compatible industrial communication lines. A 4-20mA, 0-10V, AI, AO, PNP or NPN circuit requires confirmation against the actual electrical parameters.\"\r\n      }\r\n    }\r\n  ]\r\n}\r\n<\/script>\r\n\r\n<script>\r\n  document.addEventListener('DOMContentLoaded', function () {\r\n    var signalPopupButtons = document.querySelectorAll(\r\n      '.leeyee-site-popup-btn'\r\n    );\r\n\r\n    signalPopupButtons.forEach(function (button) {\r\n      button.addEventListener('click', function (event) {\r\n        event.preventDefault();\r\n\r\n        var realPopupTrigger = document.querySelector(\r\n          '.w-popup.ush_popup_1 .w-popup-trigger'\r\n        );\r\n\r\n        if (realPopupTrigger) {\r\n          realPopupTrigger.click();\r\n        } else {\r\n          window.open(\r\n            'https:\/\/www.cnspd.com\/contact\/',\r\n            '_blank',\r\n            'noopener'\r\n          );\r\n        }\r\n      });\r\n    });\r\n  });\r\n<\/script>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t","protected":false},"excerpt":{"rendered":"<p>Industrial Signal Protection \u00b7 PLC I\/O \u00b7 OEM Selection How to Select a 24V Signal Surge Protector A 24V marking alone is not enough to select a surge protector for a sensor or PLC I\/O circuit. The correct SPD must also match the signal type, circuit topology, conductor count, loop current, permissible series resistance, protection&#8230;<\/p>","protected":false},"author":18,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1,488,422],"tags":[],"class_list":["post-30176","post","type-post","status-publish","format-standard","hentry","category-news","category-surge-protection","category-industry-news"],"acf":[],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v27.9 - https:\/\/yoast.com\/product\/yoast-seo-wordpress\/ -->\n<title>24V Signal Surge Protector for PLC I\/O &amp; Sensors | LEEYEE<\/title>\n<meta name=\"description\" content=\"Select a 24V signal surge protector for PLC DI, DO, AI, AO, 4\u201320mA and 0\u201310V sensor circuits. Compare wiring, installation and OEM order checks.\" \/>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/www.cnspd.com\/pt\/24v-signal-surge-protector\/\" \/>\n<meta property=\"og:locale\" content=\"pt_PT\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"24V Signal Surge Protector for PLC I\/O &amp; Sensors | LEEYEE\" \/>\n<meta property=\"og:description\" content=\"Select a 24V signal surge protector for PLC DI, DO, AI, AO, 4\u201320mA and 0\u201310V sensor circuits. 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