{"id":31023,"date":"2026-09-15T09:02:26","date_gmt":"2026-09-15T01:02:26","guid":{"rendered":"https:\/\/www.cnspd.com\/?p=31023"},"modified":"2026-09-15T09:04:11","modified_gmt":"2026-09-15T01:04:11","slug":"automatic-transfer-switch-for-generator-backup-power-systems","status":"publish","type":"post","link":"https:\/\/www.cnspd.com\/it\/generator-automatic-transfer-switch\/","title":{"rendered":"Commutatore automatico per sistemi di alimentazione di riserva con generatore"},"content":{"rendered":"\t\t<div data-elementor-type=\"wp-post\" data-elementor-id=\"31023\" class=\"elementor elementor-31023\" data-elementor-post-type=\"post\">\n\t\t\t\t<div class=\"elementor-element elementor-element-7a7b602 e-flex e-con-boxed e-con e-parent\" data-id=\"7a7b602\" 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-2ccf087 elementor-widget elementor-widget-html\" data-id=\"2ccf087\" 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#leeyee-generator-ats-guide{\r\n  --ly-blue:#004898;\r\n  --ly-blue-dark:#00366f;\r\n  --ly-blue-soft:#eef5ff;\r\n  --ly-blue-soft-2:#f7fbff;\r\n  --ly-text:#22313b;\r\n  --ly-heading:#142a38;\r\n  --ly-muted:#5d6b75;\r\n  --ly-line:#dbe5ec;\r\n  --ly-warning:#915b08;\r\n  --ly-warning-bg:#fff8e9;\r\n  --ly-success:#216746;\r\n  --ly-success-bg:#f2faf6;\r\n  width:100%;\r\n  max-width:860px;\r\n  margin:0 auto;\r\n  padding:10px 18px 64px;\r\n  box-sizing:border-box;\r\n  color:var(--ly-text);\r\n  font-family:Arial,Helvetica,sans-serif;\r\n  font-size:16.5px;\r\n  line-height:1.7;\r\n  overflow-wrap:anywhere;\r\n}\r\n#leeyee-generator-ats-guide *,\r\n#leeyee-generator-ats-guide *::before,\r\n#leeyee-generator-ats-guide *::after{\r\n  box-sizing:border-box;\r\n}\r\n#leeyee-generator-ats-guide p{\r\n  margin:0 0 18px;\r\n}\r\n#leeyee-generator-ats-guide strong{\r\n  color:#162b39;\r\n}\r\n#leeyee-generator-ats-guide a:not(.leeyee-site-popup-btn){\r\n  color:var(--ly-blue);\r\n  text-decoration:underline;\r\n  text-decoration-thickness:1px;\r\n  text-underline-offset:3px;\r\n}\r\n#leeyee-generator-ats-guide h2{\r\n  margin:52px 0 18px;\r\n  color:var(--ly-heading);\r\n  font-size:clamp(28px,3vw,33px);\r\n  line-height:1.22;\r\n  letter-spacing:-.02em;\r\n}\r\n#leeyee-generator-ats-guide h3{\r\n  margin:32px 0 12px;\r\n  color:#19384b;\r\n  font-size:clamp(22px,2.4vw,25px);\r\n  line-height:1.3;\r\n}\r\n#leeyee-generator-ats-guide .ly-lede{\r\n  margin:0 0 16px;\r\n  color:#344854;\r\n  font-size:18px;\r\n  line-height:1.7;\r\n}\r\n#leeyee-generator-ats-guide .ly-scope{\r\n  margin:0 0 28px;\r\n  padding:12px 16px;\r\n  border-left:3px solid var(--ly-blue);\r\n  background:var(--ly-blue-soft-2);\r\n  color:#485965;\r\n  font-size:15px;\r\n}\r\n#leeyee-generator-ats-guide .ly-quick{\r\n  margin:26px 0 28px;\r\n  padding:25px 27px;\r\n  border:1px solid #bed3e5;\r\n  border-left:5px solid var(--ly-blue);\r\n  border-radius:10px;\r\n  background:var(--ly-blue-soft-2);\r\n}\r\n#leeyee-generator-ats-guide .ly-quick h2{\r\n  margin:0 0 14px;\r\n  font-size:25px;\r\n}\r\n#leeyee-generator-ats-guide .ly-quick p:last-of-type{\r\n  margin-bottom:0;\r\n}\r\n#leeyee-generator-ats-guide .ly-keyline{\r\n  margin-top:18px;\r\n  padding-top:16px;\r\n  border-top:1px solid #ccdce8;\r\n  color:var(--ly-blue-dark);\r\n  font-weight:700;\r\n}\r\n#leeyee-generator-ats-guide .ly-note,\r\n#leeyee-generator-ats-guide .ly-warning,\r\n#leeyee-generator-ats-guide .ly-buyer{\r\n  margin:25px 0;\r\n  padding:19px 21px;\r\n  border-radius:9px;\r\n}\r\n#leeyee-generator-ats-guide .ly-note{\r\n  border:1px solid #c7dced;\r\n  background:var(--ly-blue-soft);\r\n}\r\n#leeyee-generator-ats-guide .ly-warning{\r\n  border:1px solid #ead4aa;\r\n  border-left:4px solid #ca8420;\r\n  background:var(--ly-warning-bg);\r\n}\r\n#leeyee-generator-ats-guide .ly-buyer{\r\n  border:1px solid #cbe5d6;\r\n  border-left:4px solid var(--ly-success);\r\n  background:var(--ly-success-bg);\r\n}\r\n#leeyee-generator-ats-guide .ly-label{\r\n  display:block;\r\n  margin:0 0 7px;\r\n  color:var(--ly-blue);\r\n  font-size:13px;\r\n  font-weight:800;\r\n  line-height:1.2;\r\n  letter-spacing:.07em;\r\n  text-transform:uppercase;\r\n}\r\n#leeyee-generator-ats-guide .ly-warning .ly-label{\r\n  color:var(--ly-warning);\r\n}\r\n#leeyee-generator-ats-guide .ly-buyer .ly-label{\r\n  color:var(--ly-success);\r\n}\r\n#leeyee-generator-ats-guide .ly-figure{\r\n  width:100%;\r\n  margin:28px auto 36px;\r\n}\r\n#leeyee-generator-ats-guide .ly-figure img{\r\n  display:block;\r\n  width:100%;\r\n  height:auto;\r\n  margin:0 auto;\r\n  border:1px solid var(--ly-line);\r\n  border-radius:10px;\r\n  background:#fff;\r\n}\r\n#leeyee-generator-ats-guide figcaption{\r\n  margin-top:10px;\r\n  color:#667681;\r\n  font-size:14px;\r\n  line-height:1.55;\r\n}\r\n#leeyee-generator-ats-guide .ly-table-note{\r\n  margin:0 0 11px;\r\n  color:#536570;\r\n  font-size:14px;\r\n}\r\n#leeyee-generator-ats-guide .ly-table-wrap{\r\n  width:100%;\r\n  margin:22px 0 12px;\r\n}\r\n#leeyee-generator-ats-guide table{\r\n  width:100%;\r\n  border-collapse:separate;\r\n  border-spacing:0;\r\n  border:1px solid var(--ly-line);\r\n  border-radius:9px;\r\n  overflow:hidden;\r\n  background:#fff;\r\n}\r\n#leeyee-generator-ats-guide th{\r\n  padding:13px 15px;\r\n  background:var(--ly-blue);\r\n  color:#fff;\r\n  font-size:14px;\r\n  line-height:1.4;\r\n  text-align:left;\r\n  vertical-align:top;\r\n}\r\n#leeyee-generator-ats-guide td{\r\n  padding:13px 15px;\r\n  border-top:1px solid var(--ly-line);\r\n  color:#334752;\r\n  line-height:1.55;\r\n  vertical-align:top;\r\n}\r\n#leeyee-generator-ats-guide tbody tr:first-child td{\r\n  border-top:0;\r\n}\r\n#leeyee-generator-ats-guide tbody tr:nth-child(even){\r\n  background:#fafcfd;\r\n}\r\n#leeyee-generator-ats-guide .ly-table-conclusion{\r\n  margin:10px 0 28px;\r\n  color:#344854;\r\n  font-weight:700;\r\n}\r\n#leeyee-generator-ats-guide .ly-selection-table{\r\n  margin:24px 0 34px;\r\n}\r\n#leeyee-generator-ats-guide .ly-selection-table h2{\r\n  margin-top:0;\r\n  font-size:26px;\r\n}\r\n#leeyee-generator-ats-guide .ly-selection-emphasis{\r\n  margin:14px 0 0;\r\n  padding:14px 17px;\r\n  border-left:4px solid var(--ly-blue);\r\n  background:#f7fbff;\r\n  color:#17394d;\r\n  font-weight:700;\r\n}\r\n#leeyee-generator-ats-guide .ly-sequence{\r\n  margin:24px 0 30px;\r\n  padding:0;\r\n  list-style:none;\r\n  counter-reset:ly-step;\r\n}\r\n#leeyee-generator-ats-guide .ly-sequence li{\r\n  position:relative;\r\n  margin:0 0 13px;\r\n  padding:17px 18px 17px 60px;\r\n  border:1px solid var(--ly-line);\r\n  border-radius:8px;\r\n  background:#fff;\r\n  counter-increment:ly-step;\r\n}\r\n#leeyee-generator-ats-guide .ly-sequence li::before{\r\n  content:counter(ly-step);\r\n  position:absolute;\r\n  top:16px;\r\n  left:16px;\r\n  width:29px;\r\n  height:29px;\r\n  border-radius:50%;\r\n  background:var(--ly-blue);\r\n  color:#fff;\r\n  font-size:14px;\r\n  font-weight:800;\r\n  line-height:29px;\r\n  text-align:center;\r\n}\r\n#leeyee-generator-ats-guide .ly-sequence li strong{\r\n  display:block;\r\n  margin-bottom:3px;\r\n}\r\n#leeyee-generator-ats-guide .ly-formula{\r\n  margin:23px 0;\r\n  padding:19px 20px;\r\n  border:1px solid var(--ly-line);\r\n  border-radius:9px;\r\n  background:#fafcfd;\r\n  color:#1f3f53;\r\n  font-size:19px;\r\n  font-weight:700;\r\n  line-height:1.5;\r\n  text-align:center;\r\n}\r\n#leeyee-generator-ats-guide .ly-formula small{\r\n  display:block;\r\n  margin-top:7px;\r\n  color:var(--ly-muted);\r\n  font-size:14px;\r\n  font-weight:400;\r\n}\r\n#leeyee-generator-ats-guide .ly-two-col{\r\n  display:grid;\r\n  grid-template-columns:1fr 1fr;\r\n  gap:16px;\r\n  margin:22px 0 30px;\r\n}\r\n#leeyee-generator-ats-guide .ly-two-col > div{\r\n  padding:19px 20px;\r\n  border:1px solid var(--ly-line);\r\n  border-radius:9px;\r\n  background:#fff;\r\n}\r\n#leeyee-generator-ats-guide .ly-two-col h3{\r\n  margin:0 0 8px;\r\n  font-size:20px;\r\n}\r\n#leeyee-generator-ats-guide .ly-checklist{\r\n  margin:25px 0 30px;\r\n  padding:24px 25px;\r\n  border:1px solid #bdd2e5;\r\n  border-radius:10px;\r\n  background:var(--ly-blue-soft-2);\r\n}\r\n#leeyee-generator-ats-guide .ly-checklist h3{\r\n  margin:0 0 17px;\r\n}\r\n#leeyee-generator-ats-guide .ly-check-grid{\r\n  display:grid;\r\n  grid-template-columns:1fr 1fr;\r\n  gap:7px 24px;\r\n}\r\n#leeyee-generator-ats-guide .ly-check-item{\r\n  position:relative;\r\n  padding:7px 0 7px 27px;\r\n  color:#354955;\r\n}\r\n#leeyee-generator-ats-guide .ly-check-item::before{\r\n  content:\"\u2713\";\r\n  position:absolute;\r\n  top:6px;\r\n  left:0;\r\n  color:var(--ly-blue);\r\n  font-weight:900;\r\n}\r\n#leeyee-generator-ats-guide .ly-cta{\r\n  margin:33px 0 42px;\r\n  padding:28px;\r\n  border:1px solid #bdd2e5;\r\n  border-radius:12px;\r\n  background:var(--ly-blue-soft);\r\n}\r\n#leeyee-generator-ats-guide .ly-cta h2{\r\n  margin:0 0 10px;\r\n  font-size:25px;\r\n}\r\n#leeyee-generator-ats-guide .ly-cta-action{\r\n  display:flex;\r\n  align-items:center;\r\n  justify-content:flex-start;\r\n  margin-top:20px;\r\n}\r\n\r\n\/* LEEYEE POPUP BUTTON *\/\r\n#leeyee-generator-ats-guide .leeyee-about-btn-light{\r\n  appearance:none;\r\n  -webkit-appearance:none;\r\n  display:inline-flex;\r\n  align-items:center;\r\n  justify-content:center;\r\n  min-height:48px;\r\n  padding:13px 24px;\r\n  margin:0;\r\n  border:2px solid var(--ly-blue);\r\n  border-radius:7px;\r\n  background:#fff;\r\n  color:var(--ly-blue);\r\n  font-family:inherit;\r\n  font-size:16px;\r\n  font-weight:700;\r\n  line-height:1.2;\r\n  text-align:center;\r\n  text-decoration:none;\r\n  cursor:pointer;\r\n  box-shadow:0 3px 10px rgba(0,72,152,.08);\r\n  transition:\r\n    background-color .2s ease,\r\n    color .2s ease,\r\n    border-color .2s ease,\r\n    box-shadow .2s ease,\r\n    transform .2s ease;\r\n}\r\n#leeyee-generator-ats-guide .leeyee-about-btn-light .w-btn-label{\r\n  display:block;\r\n  color:inherit;\r\n  font:inherit;\r\n  line-height:inherit;\r\n}\r\n#leeyee-generator-ats-guide .leeyee-about-btn-light:hover{\r\n  border-color:var(--ly-blue);\r\n  background:var(--ly-blue);\r\n  color:#fff;\r\n  box-shadow:0 6px 16px rgba(0,72,152,.16);\r\n  transform:translateY(-1px);\r\n}\r\n#leeyee-generator-ats-guide .leeyee-about-btn-light:active{\r\n  transform:translateY(0);\r\n  box-shadow:0 2px 7px rgba(0,72,152,.12);\r\n}\r\n#leeyee-generator-ats-guide .leeyee-about-btn-light:focus{\r\n  outline:none;\r\n}\r\n#leeyee-generator-ats-guide .leeyee-about-btn-light:focus-visible{\r\n  outline:3px solid rgba(0,72,152,.2);\r\n  outline-offset:3px;\r\n}\r\n#leeyee-generator-ats-guide .ly-faq{\r\n  margin-top:15px;\r\n  border-top:1px solid var(--ly-line);\r\n}\r\n#leeyee-generator-ats-guide .ly-faq details{\r\n  border-bottom:1px solid var(--ly-line);\r\n}\r\n#leeyee-generator-ats-guide .ly-faq summary{\r\n  position:relative;\r\n  padding:18px 34px 18px 0;\r\n  cursor:pointer;\r\n  list-style:none;\r\n  color:#1b3749;\r\n  font-weight:700;\r\n}\r\n#leeyee-generator-ats-guide .ly-faq summary::-webkit-details-marker{\r\n  display:none;\r\n}\r\n#leeyee-generator-ats-guide .ly-faq summary::after{\r\n  content:\"+\";\r\n  position:absolute;\r\n  top:13px;\r\n  right:4px;\r\n  color:var(--ly-blue);\r\n  font-size:25px;\r\n  font-weight:400;\r\n}\r\n#leeyee-generator-ats-guide .ly-faq details[open] summary::after{\r\n  content:\"\u2013\";\r\n}\r\n#leeyee-generator-ats-guide .ly-faq-answer{\r\n  padding:0 28px 18px 0;\r\n  color:#455762;\r\n}\r\n#leeyee-generator-ats-guide .ly-related{\r\n  margin-top:42px;\r\n  padding-top:5px;\r\n  border-top:1px solid var(--ly-line);\r\n}\r\n#leeyee-generator-ats-guide .ly-refs{\r\n  margin-top:50px;\r\n}\r\n#leeyee-generator-ats-guide .ly-refs ol{\r\n  margin:15px 0 0;\r\n  padding-left:22px;\r\n}\r\n#leeyee-generator-ats-guide .ly-refs li{\r\n  margin:0 0 13px;\r\n  padding-left:4px;\r\n  color:#4e606b;\r\n  font-size:14px;\r\n  line-height:1.62;\r\n}\r\n#leeyee-generator-ats-guide sup{\r\n  line-height:0;\r\n}\r\n#leeyee-generator-ats-guide sup a{\r\n  font-weight:700;\r\n  text-decoration:none;\r\n}\r\n#leeyee-generator-ats-guide .ly-small{\r\n  color:var(--ly-muted);\r\n  font-size:14px;\r\n}\r\n@media(max-width:1024px){\r\n  #leeyee-generator-ats-guide{\r\n    max-width:840px;\r\n  }\r\n}\r\n@media(max-width:820px){\r\n  #leeyee-generator-ats-guide{\r\n    padding-left:17px;\r\n    padding-right:17px;\r\n  }\r\n}\r\n@media(max-width:768px){\r\n  #leeyee-generator-ats-guide{\r\n    font-size:16px;\r\n  }\r\n  #leeyee-generator-ats-guide h2{\r\n    margin-top:45px;\r\n  }\r\n  #leeyee-generator-ats-guide .ly-quick,\r\n  #leeyee-generator-ats-guide .ly-cta,\r\n  #leeyee-generator-ats-guide .ly-checklist{\r\n    padding:21px 20px;\r\n  }\r\n  #leeyee-generator-ats-guide .ly-two-col,\r\n  #leeyee-generator-ats-guide .ly-check-grid{\r\n    grid-template-columns:1fr;\r\n  }\r\n}\r\n@media(max-width:600px){\r\n  #leeyee-generator-ats-guide .ly-stack-table,\r\n  #leeyee-generator-ats-guide .ly-stack-table tbody,\r\n  #leeyee-generator-ats-guide .ly-stack-table tr,\r\n  #leeyee-generator-ats-guide .ly-stack-table td{\r\n    display:block;\r\n    width:100%;\r\n  }\r\n  #leeyee-generator-ats-guide .ly-stack-table{\r\n    border:0;\r\n    background:transparent;\r\n  }\r\n  #leeyee-generator-ats-guide .ly-stack-table thead{\r\n    display:none;\r\n  }\r\n  #leeyee-generator-ats-guide .ly-stack-table tr{\r\n    margin-bottom:13px;\r\n    border:1px solid var(--ly-line);\r\n    border-radius:8px;\r\n    overflow:hidden;\r\n    background:#fff;\r\n  }\r\n  #leeyee-generator-ats-guide .ly-stack-table td{\r\n    display:grid;\r\n    grid-template-columns:minmax(110px,38%) 1fr;\r\n    gap:11px;\r\n    border-top:1px solid var(--ly-line);\r\n  }\r\n  #leeyee-generator-ats-guide .ly-stack-table td:first-child{\r\n    border-top:0;\r\n  }\r\n  #leeyee-generator-ats-guide .ly-stack-table td::before{\r\n    content:attr(data-label);\r\n    color:var(--ly-blue-dark);\r\n    font-weight:700;\r\n  }\r\n  #leeyee-generator-ats-guide .ly-cta-action{\r\n    display:block;\r\n  }\r\n  #leeyee-generator-ats-guide .leeyee-about-btn-light{\r\n    width:100%;\r\n    min-height:50px;\r\n    padding:14px 18px;\r\n  }\r\n}\r\n@media(max-width:480px){\r\n  #leeyee-generator-ats-guide{\r\n    padding-left:15px;\r\n    padding-right:15px;\r\n  }\r\n  #leeyee-generator-ats-guide .ly-lede{\r\n    font-size:17px;\r\n  }\r\n  #leeyee-generator-ats-guide .ly-note,\r\n  #leeyee-generator-ats-guide .ly-warning,\r\n  #leeyee-generator-ats-guide .ly-buyer{\r\n    padding:17px;\r\n  }\r\n  #leeyee-generator-ats-guide .ly-sequence li{\r\n    padding-left:54px;\r\n  }\r\n}\r\n@media(max-width:390px){\r\n  #leeyee-generator-ats-guide{\r\n    padding-left:14px;\r\n    padding-right:14px;\r\n  }\r\n  #leeyee-generator-ats-guide .ly-stack-table td{\r\n    grid-template-columns:1fr;\r\n    gap:4px;\r\n  }\r\n}\r\n@media(max-width:320px){\r\n  #leeyee-generator-ats-guide{\r\n    padding-left:12px;\r\n    padding-right:12px;\r\n  }\r\n  #leeyee-generator-ats-guide .ly-quick,\r\n  #leeyee-generator-ats-guide .ly-cta,\r\n  #leeyee-generator-ats-guide .ly-checklist{\r\n    padding-left:16px;\r\n    padding-right:16px;\r\n  }\r\n}\r\n<\/style>\r\n\r\n<article id=\"leeyee-generator-ats-guide\" aria-label=\"Automatic transfer switch for generator backup power systems guide\">\r\n\r\n  <p class=\"ly-lede\">\r\n    An <strong>automatic transfer switch for a generator backup system<\/strong> should not be selected as an isolated switch. The ATS must match the utility source, generator output, generator controller, backed-up load, phase and neutral arrangement, transfer sequence, protection design and project requirements.\r\n  <\/p>\r\n\r\n  <div class=\"ly-scope\">\r\n    This guide is for generator-set integrators, ATS panel builders, electrical contractors, industrial and commercial project teams, distributors and OEM buyers. It focuses on utility-to-generator backup architecture and engineering selection rather than household generator operation.\r\n  <\/div>\r\n\r\n  <section class=\"ly-quick\">\r\n    <div id=\"ez-toc-container\" class=\"ez-toc-v2_0_87 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\/it\/generator-automatic-transfer-switch\/#quick-answer-how-does-a-generator-ats-work\" >Quick Answer: How Does a Generator ATS Work?<\/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\/it\/generator-automatic-transfer-switch\/#generator-ats-selection-at-a-glance\" >Generator ATS Selection at a Glance<\/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\/it\/generator-automatic-transfer-switch\/#where-does-the-ats-sit-in-a-generator-backup-system\" >Where Does the ATS Sit in a Generator Backup System?<\/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\/it\/generator-automatic-transfer-switch\/#what-happens-when-utility-power-fails\" >What Happens When Utility Power Fails?<\/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\/it\/generator-automatic-transfer-switch\/#what-happens-when-utility-power-returns\" >What Happens When Utility Power Returns?<\/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\/it\/generator-automatic-transfer-switch\/#how-long-does-generator-backup-transfer-take\" >How Long Does Generator Backup Transfer Take?<\/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\/it\/generator-automatic-transfer-switch\/#ats-controller-vs-generator-controller-who-does-what\" >ATS Controller vs Generator Controller: Who Does What?<\/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\/it\/generator-automatic-transfer-switch\/#how-should-you-select-an-ats-for-a-generator-backup-system\" >How Should You Select an ATS for a Generator Backup System?<\/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\/it\/generator-automatic-transfer-switch\/#must-generator-capacity-and-ats-current-rating-be-the-same\" >Must Generator Capacity and ATS Current Rating Be the Same?<\/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\/it\/generator-automatic-transfer-switch\/#single-phase-vs-three-phase-generator-ats-selection\" >Single-Phase vs Three-Phase Generator ATS Selection<\/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\/it\/generator-automatic-transfer-switch\/#open-transition-delayed-transition-or-closed-transition\" >Open Transition, Delayed Transition or Closed Transition?<\/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\/it\/generator-automatic-transfer-switch\/#do-you-need-an-ats-device-or-a-complete-ats-panel\" >Do You Need an ATS Device or a Complete ATS Panel?<\/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\/it\/generator-automatic-transfer-switch\/#when-are-manual-operation-and-bypass-useful\" >When Are Manual Operation and Bypass Useful?<\/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\/it\/generator-automatic-transfer-switch\/#can-several-ats-units-use-one-generator\" >Can Several ATS Units Use One Generator?<\/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\/it\/generator-automatic-transfer-switch\/#common-generator-ats-selection-mistakes\" >Common Generator ATS Selection Mistakes<\/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\/it\/generator-automatic-transfer-switch\/#where-can-a-compact-leeyee-ats-fit\" >Where Can a Compact LEEYEE ATS Fit?<\/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\/it\/generator-automatic-transfer-switch\/#which-standards-should-be-checked-for-a-generator-ats-project\" >Which Standards Should Be Checked for a Generator ATS Project?<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-18\" href=\"#\" data-href=\"https:\/\/www.cnspd.com\/it\/generator-automatic-transfer-switch\/#before-ordering-an-automatic-transfer-switch-for-a-generator\" >Before Ordering an Automatic Transfer Switch for a Generator<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-19\" href=\"#\" data-href=\"https:\/\/www.cnspd.com\/it\/generator-automatic-transfer-switch\/#need-a-generator-ats-configuration-review\" >Need a Generator ATS Configuration Review?<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-20\" href=\"#\" data-href=\"https:\/\/www.cnspd.com\/it\/generator-automatic-transfer-switch\/#frequently-asked-questions-about-generator-ats-systems\" >Frequently Asked Questions About Generator ATS Systems<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-21\" href=\"#\" data-href=\"https:\/\/www.cnspd.com\/it\/generator-automatic-transfer-switch\/#related-ats-reading\" >Related ATS Reading<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-22\" href=\"#\" data-href=\"https:\/\/www.cnspd.com\/it\/generator-automatic-transfer-switch\/#references\" >References<\/a><\/li><\/ul><\/nav><\/div>\n<h2><span class=\"ez-toc-section\" id=\"quick-answer-how-does-a-generator-ats-work\"><\/span>Quick Answer: How Does a Generator ATS Work?<span class=\"ez-toc-section-end\"><\/span><\/h2>\r\n\r\n    <p>\r\n      While utility power is acceptable, the ATS keeps the backed-up load on the normal source. If the utility becomes unacceptable for the configured start delay, the ATS or associated controller can issue a generator-start request. The generator controller then starts the genset and builds voltage and frequency.\r\n    <\/p>\r\n\r\n    <p>\r\n      The ATS should transfer the load only after the generator source reaches the controller's acceptable conditions and any configured transfer delay has expired. When utility power returns and remains acceptable for the retransfer delay, the load returns to utility. A stop or cooldown delay can then allow the generator to run unloaded before shutdown.<sup><a href=\"#ref-2\">[2]<\/a><\/sup>\r\n    <\/p>\r\n\r\n    <p>\r\n      <strong>Do not assume that every automatic transfer switch includes a generator engine-start output.<\/strong> Some transfer-switch controllers provide dedicated engine-start contacts; other compact source-transfer devices only transfer between AC sources that have already become available. The actual generator-start interface must be confirmed before ordering.<sup><a href=\"#ref-3\">[3]<\/a><\/sup>\r\n    <\/p>\r\n\r\n    <div class=\"ly-keyline\">\r\n      Buyer meaning: generator model, controller model, voltage, frequency, phase, backed-up load current, neutral arrangement and generator-start interface all affect ATS selection.\r\n    <\/div>\r\n  <\/section>\r\n\r\n  <section class=\"ly-selection-table\">\r\n    <h2><span class=\"ez-toc-section\" id=\"generator-ats-selection-at-a-glance\"><\/span>Generator ATS Selection at a Glance<span class=\"ez-toc-section-end\"><\/span><\/h2>\r\n\r\n    <p class=\"ly-table-note\">\r\n      Before comparing ATS models, confirm these project conditions first.\r\n    <\/p>\r\n\r\n    <div class=\"ly-table-wrap\">\r\n      <table class=\"ly-stack-table\">\r\n        <thead>\r\n          <tr>\r\n            <th>Confirm First<\/th>\r\n            <th>Why It Changes ATS Selection<\/th>\r\n          <\/tr>\r\n        <\/thead>\r\n        <tbody>\r\n          <tr>\r\n            <td data-label=\"Confirm\">Generator voltage and phase<\/td>\r\n            <td data-label=\"Why It Matters\">Determines compatible ATS voltage and pole configuration<\/td>\r\n          <\/tr>\r\n          <tr>\r\n            <td data-label=\"Confirm\">Maximum backed-up load current<\/td>\r\n            <td data-label=\"Why It Matters\">Determines the continuous-current requirement of the ATS<\/td>\r\n          <\/tr>\r\n          <tr>\r\n            <td data-label=\"Confirm\">Generator controller model<\/td>\r\n            <td data-label=\"Why It Matters\">Determines whether and how generator auto-start can be coordinated<\/td>\r\n          <\/tr>\r\n          <tr>\r\n            <td data-label=\"Confirm\">Neutral and earthing arrangement<\/td>\r\n            <td data-label=\"Why It Matters\">Affects whether the neutral must be switched and whether 3P or 4P is appropriate<\/td>\r\n          <\/tr>\r\n          <tr>\r\n            <td data-label=\"Confirm\">Motor \/ transformer loads<\/td>\r\n            <td data-label=\"Why It Matters\">Starting and inrush current can affect switching duty and generator performance<\/td>\r\n          <\/tr>\r\n          <tr>\r\n            <td data-label=\"Confirm\">Maximum acceptable interruption<\/td>\r\n            <td data-label=\"Why It Matters\">Determines whether ordinary open-transition transfer is sufficient<\/td>\r\n          <\/tr>\r\n          <tr>\r\n            <td data-label=\"Confirm\">ATS device or complete panel<\/td>\r\n            <td data-label=\"Why It Matters\">Defines whether the supplier provides only the transfer device or an engineered cabinet<\/td>\r\n          <\/tr>\r\n        <\/tbody>\r\n      <\/table>\r\n    <\/div>\r\n\r\n    <div class=\"ly-selection-emphasis\">\r\n      Do not choose a generator ATS from generator kVA alone.\r\n    <\/div>\r\n  <\/section>\r\n\r\n  <figure class=\"ly-figure\">\r\n    <img fetchpriority=\"high\"\r\n      src=\"https:\/\/www.cnspd.com\/wp-content\/uploads\/2026\/09\/generator-ats-backup-power-system-architecture.webp\"\r\n      alt=\"Utility and generator backup power system architecture showing ATS, generator controller and backed-up load\"\r\n      width=\"1448\"\r\n      height=\"1086\"\r\n      loading=\"eager\"\r\n      decoding=\"async\">\r\n    <figcaption>\r\n      Utility-generator ATS architecture. The electrical power path and generator start-control path are separate functions. Final source monitoring, neutral switching and generator-start wiring must follow the actual ATS, generator controller and project design.\r\n    <\/figcaption>\r\n  <\/figure>\r\n\r\n  <h2><span class=\"ez-toc-section\" id=\"where-does-the-ats-sit-in-a-generator-backup-system\"><\/span>Where Does the ATS Sit in a Generator Backup System?<span class=\"ez-toc-section-end\"><\/span><\/h2>\r\n\r\n  <p>\r\n    The ATS is installed at the point where a backed-up load must select between the normal utility source and the generator source. Its location is determined by the electrical distribution architecture, not simply by how close it is to the generator.\r\n  <\/p>\r\n\r\n  <p>\r\n    In a whole-section backup design, the ATS can feed an entire backed-up distribution section. In a selected-load design, it can feed only a critical-load panel or dedicated feeder while non-critical loads remain outside the generator-backed path.\r\n  <\/p>\r\n\r\n  <div class=\"ly-note\">\r\n    <span class=\"ly-label\">Engineering Meaning<\/span>\r\n    Define the <strong>backup boundary<\/strong> before selecting the ATS. A generator may have enough capacity for several circuits, but the ATS must be selected for the loads that actually pass through it.\r\n  <\/div>\r\n\r\n  <h2><span class=\"ez-toc-section\" id=\"what-happens-when-utility-power-fails\"><\/span>What Happens When Utility Power Fails?<span class=\"ez-toc-section-end\"><\/span><\/h2>\r\n\r\n  <p>\r\n    A professional generator backup sequence involves several decisions. \u201cUtility fails, generator starts, ATS switches\u201d is only the simplified summary.\r\n  <\/p>\r\n\r\n  <ol class=\"ly-sequence\">\r\n    <li>\r\n      <strong>The ATS monitors the normal source.<\/strong>\r\n      Depending on the controller, monitoring can include voltage, frequency and phase-related conditions. The available functions and trip or pickup settings are product-specific.<sup><a href=\"#ref-2\">[2]<\/a><\/sup>\r\n    <\/li>\r\n\r\n    <li>\r\n      <strong>A start delay can filter short disturbances.<\/strong>\r\n      Cummins describes a start time delay as a means of preventing unnecessary generator starts or transfer sequences for short-duration disturbances of the normal source.<sup><a href=\"#ref-2\">[2]<\/a><\/sup>\r\n    <\/li>\r\n\r\n    <li>\r\n      <strong>The generator receives a start request.<\/strong>\r\n      If the transfer-control system includes an engine-start interface, the ATS\/controller changes the required contact state or sends the specified start command to the generator controller. Schneider Electric \/ ASCO documentation shows that contact logic can differ by equipment.<sup><a href=\"#ref-3\">[3]<\/a><\/sup>\r\n    <\/li>\r\n\r\n    <li>\r\n      <strong>The generator starts and builds its output.<\/strong>\r\n      The genset controller handles engine starting and generator operation. Engine running status alone does not prove that the generator source is ready to carry the load.\r\n    <\/li>\r\n\r\n    <li>\r\n      <strong>The ATS verifies that the backup source is acceptable.<\/strong>\r\n      Generator voltage and, where monitored, frequency must reach the controller's acceptable limits before the transfer sequence proceeds.<sup><a href=\"#ref-2\">[2]<\/a><\/sup>\r\n    <\/li>\r\n\r\n    <li>\r\n      <strong>The transfer delay expires.<\/strong>\r\n      A transfer delay can allow the generator output to stabilize before the load is applied.<sup><a href=\"#ref-2\">[2]<\/a><\/sup>\r\n    <\/li>\r\n\r\n    <li>\r\n      <strong>The ATS transfers the load.<\/strong>\r\n      In a conventional open-transition arrangement, the connected source is opened before the alternative source is connected. Other transition modes require transfer equipment and controls specifically designed for those functions.<sup><a href=\"#ref-1\">[1]<\/a><\/sup>\r\n    <\/li>\r\n  <\/ol>\r\n\r\n  <figure class=\"ly-figure\">\r\n    <img loading=\"lazy\"\r\n      src=\"https:\/\/www.cnspd.com\/wp-content\/uploads\/2026\/09\/generator-ats-transfer-sequence-timeline.webp\"\r\n      alt=\"Generator ATS transfer sequence from utility failure through generator start, load transfer, utility return and cooldown\"\r\n      width=\"1448\"\r\n      height=\"1086\"\r\n      loading=\"lazy\"\r\n      decoding=\"async\">\r\n    <figcaption>\r\n      Typical utility-to-generator transfer sequence. Exact delays are not universal values; they depend on the ATS\/controller, generator, load, system design and project settings.\r\n    <\/figcaption>\r\n  <\/figure>\r\n\r\n  <div class=\"ly-warning\">\r\n    <span class=\"ly-label\">Important Distinction<\/span>\r\n    <strong>ATS switching time is not the same as total generator backup restoration time.<\/strong>\r\n    A transfer mechanism can operate quickly after the emergency source becomes acceptable, but a stopped generator still needs time to receive the start request, crank, reach operating speed, build acceptable voltage and frequency and satisfy the configured transfer conditions.\r\n  <\/div>\r\n\r\n  <h2><span class=\"ez-toc-section\" id=\"what-happens-when-utility-power-returns\"><\/span>What Happens When Utility Power Returns?<span class=\"ez-toc-section-end\"><\/span><\/h2>\r\n\r\n  <p>\r\n    A generator ATS does not necessarily return the load to utility the instant normal voltage reappears. A recently restored source may still be unstable.\r\n  <\/p>\r\n\r\n  <ol class=\"ly-sequence\">\r\n    <li>\r\n      <strong>The ATS detects the returning normal source.<\/strong>\r\n      Utility power must return to the controller's acceptable source conditions.\r\n    <\/li>\r\n\r\n    <li>\r\n      <strong>The retransfer delay begins.<\/strong>\r\n      The delay allows the normal source to remain stable before the load is moved away from generator power and helps reduce repeated transfer\/retransfer cycles when utility power is unstable.<sup><a href=\"#ref-2\">[2]<\/a><\/sup>\r\n    <\/li>\r\n\r\n    <li>\r\n      <strong>The load returns to utility.<\/strong>\r\n      After the retransfer conditions are satisfied, the normal source again supplies the backed-up load.\r\n    <\/li>\r\n\r\n    <li>\r\n      <strong>The generator can continue running unloaded.<\/strong>\r\n      A generator stop or cooldown delay can keep the genset operating without load after retransfer.<sup><a href=\"#ref-2\">[2]<\/a><\/sup>\r\n    <\/li>\r\n\r\n    <li>\r\n      <strong>The generator returns to standby.<\/strong>\r\n      The generator controller completes its shutdown sequence and waits for the next valid start request.\r\n    <\/li>\r\n  <\/ol>\r\n\r\n  <h2><span class=\"ez-toc-section\" id=\"how-long-does-generator-backup-transfer-take\"><\/span>How Long Does Generator Backup Transfer Take?<span class=\"ez-toc-section-end\"><\/span><\/h2>\r\n\r\n  <p>\r\n    There is no single universal transfer time from utility failure to generator-powered load. Total restoration time depends on the control settings and the generator itself.\r\n  <\/p>\r\n\r\n  <div class=\"ly-formula\">\r\n    Total time to generator power \u2248 start delay + generator starting\/stabilization + transfer delay + ATS switching operation\r\n    <small>Actual sequence and timing must be confirmed for the specific controller, genset and project.<\/small>\r\n  <\/div>\r\n\r\n  <p>\r\n    This is why a catalogue value such as \u201ctransfer switching time\u201d should not be presented as the complete outage-to-generator recovery time.\r\n  <\/p>\r\n\r\n  <div class=\"ly-buyer\">\r\n    <span class=\"ly-label\">Buyer Meaning<\/span>\r\n    If a project specifies a maximum permitted interruption time, ask for the complete generator-start and transfer sequence instead of comparing ATS products only by their switching-time value.\r\n  <\/div>\r\n\r\n  <h2><span class=\"ez-toc-section\" id=\"ats-controller-vs-generator-controller-who-does-what\"><\/span>ATS Controller vs Generator Controller: Who Does What?<span class=\"ez-toc-section-end\"><\/span><\/h2>\r\n\r\n  <p>\r\n    A useful way to understand the system is to treat the ATS controller as the <strong>source decision controller<\/strong> and the genset controller as the <strong>generator machine controller<\/strong>.\r\n  <\/p>\r\n\r\n  <p class=\"ly-table-note\">\r\n    The responsibility split below is typical rather than universal. The actual controller and wiring documentation takes priority.\r\n  <\/p>\r\n\r\n  <div class=\"ly-table-wrap\">\r\n    <table class=\"ly-stack-table\">\r\n      <thead>\r\n        <tr>\r\n          <th>Function<\/th>\r\n          <th>Typical Responsibility<\/th>\r\n          <th>Project Confirmation<\/th>\r\n        <\/tr>\r\n      <\/thead>\r\n      <tbody>\r\n        <tr>\r\n          <td data-label=\"Function\">Monitor utility source<\/td>\r\n          <td data-label=\"Responsibility\">ATS \/ transfer controller<\/td>\r\n          <td data-label=\"Confirm\">Voltage, frequency and phase-monitoring functions actually provided<\/td>\r\n        <\/tr>\r\n        <tr>\r\n          <td data-label=\"Function\">Request generator start<\/td>\r\n          <td data-label=\"Responsibility\">ATS\/controller if an engine-start output is provided<\/td>\r\n          <td data-label=\"Confirm\">Contact logic, terminals and interface requirements<\/td>\r\n        <\/tr>\r\n        <tr>\r\n          <td data-label=\"Function\">Crank and start engine<\/td>\r\n          <td data-label=\"Responsibility\">Generator controller<\/td>\r\n          <td data-label=\"Confirm\">Generator controller model and remote-start input<\/td>\r\n        <\/tr>\r\n        <tr>\r\n          <td data-label=\"Function\">Engine protection<\/td>\r\n          <td data-label=\"Responsibility\">Generator controller<\/td>\r\n          <td data-label=\"Confirm\">Use the genset manufacturer's control documentation<\/td>\r\n        <\/tr>\r\n        <tr>\r\n          <td data-label=\"Function\">Accept emergency source<\/td>\r\n          <td data-label=\"Responsibility\">ATS \/ transfer controller<\/td>\r\n          <td data-label=\"Confirm\">Generator voltage and frequency acceptance settings<\/td>\r\n        <\/tr>\r\n        <tr>\r\n          <td data-label=\"Function\">Transfer the load<\/td>\r\n          <td data-label=\"Responsibility\">Transfer switching equipment<\/td>\r\n          <td data-label=\"Confirm\">Transition type, poles, current rating and switching duty<\/td>\r\n        <\/tr>\r\n        <tr>\r\n          <td data-label=\"Function\">Cooldown \/ shutdown<\/td>\r\n          <td data-label=\"Responsibility\">Coordinated ATS and generator control<\/td>\r\n          <td data-label=\"Confirm\">Where the stop delay is implemented and how shutdown is commanded<\/td>\r\n        <\/tr>\r\n      <\/tbody>\r\n    <\/table>\r\n  <\/div>\r\n\r\n  <p class=\"ly-table-conclusion\">\r\n    Procurement conclusion: the generator controller model becomes an important ATS enquiry parameter whenever automatic genset starting is part of the project.\r\n  <\/p>\r\n\r\n  <h3>Does Every Automatic Transfer Switch Start the Generator?<\/h3>\r\n\r\n  <p>\r\n    No. Automatic source transfer and automatic engine starting are related functions, but they should not be treated as the same feature.\r\n  <\/p>\r\n\r\n  <p>\r\n    ASCO transfer-switch documentation identifies dedicated engine-start terminals and shows that contact logic and terminal arrangements vary by transfer-switch model.<sup><a href=\"#ref-3\">[3]<\/a><\/sup> A compact source-transfer device may instead depend on a separate controller or another system to make the generator source available.\r\n  <\/p>\r\n\r\n  <div class=\"ly-warning\">\r\n    <span class=\"ly-label\">Procurement Risk<\/span>\r\n    If the generator normally remains stopped, confirm exactly which controller sends the start request. Otherwise, the ATS may correctly detect loss of utility while the generator input remains unavailable because no valid start command has been issued.\r\n  <\/div>\r\n\r\n  <h2><span class=\"ez-toc-section\" id=\"how-should-you-select-an-ats-for-a-generator-backup-system\"><\/span>How Should You Select an ATS for a Generator Backup System?<span class=\"ez-toc-section-end\"><\/span><\/h2>\r\n\r\n  <h3>1. Confirm Utility and Generator Voltage<\/h3>\r\n\r\n  <p>\r\n    The utility voltage, generator output voltage and ATS rated operating voltage must be compatible with the intended system. Confirm the actual line-to-line and line-to-neutral arrangement rather than relying only on a country-level nominal voltage.\r\n  <\/p>\r\n\r\n  <h3>2. Confirm Frequency<\/h3>\r\n\r\n  <p>\r\n    Confirm whether the project operates at 50 Hz or 60 Hz and whether both the ATS controller and generator are suitable for that system. Source-monitoring functions must also be configured for the intended frequency.\r\n  <\/p>\r\n\r\n  <h3>3. Confirm Single-Phase or Three-Phase Architecture<\/h3>\r\n\r\n  <p>\r\n    Single-phase and three-phase generator systems require different conductor and pole arrangements. However, phase count alone does not determine whether the neutral should be switched.\r\n  <\/p>\r\n\r\n  <h3>4. Decide Whether the Neutral Must Be Switched<\/h3>\r\n\r\n  <p>\r\n    Neutral switching depends on the facility grounding arrangement, generator neutral treatment and any ground-fault protection scheme. Cummins notes that the choice between a solid neutral connection and a switched neutral depends on how the distribution system is grounded and whether ground-fault protection is used.<sup><a href=\"#ref-2\">[2]<\/a><\/sup>\r\n  <\/p>\r\n\r\n  <div class=\"ly-note\">\r\n    <span class=\"ly-label\">Project Confirmation Required<\/span>\r\n    Do not use a universal rule such as \u201csingle phase always uses 2P\u201d or \u201cthree phase always uses 4P.\u201d Confirm the single-line diagram, generator neutral arrangement, earthing method and applicable local requirements before fixing the pole configuration.\r\n  <\/div>\r\n\r\n  <h3>5. Select ATS Current From the Load It Must Carry<\/h3>\r\n\r\n  <p>\r\n    ATS continuous-current selection starts from the current carried by the transfer equipment. Cummins describes continuous current as being selected according to the total connected-load requirement in a manner comparable to conductor sizing.<sup><a href=\"#ref-2\">[2]<\/a><\/sup>\r\n  <\/p>\r\n\r\n  <p>\r\n    Generator nameplate capacity remains useful because it establishes the available source capacity, but generator kVA and ATS amperes are different ratings.\r\n  <\/p>\r\n\r\n  <div class=\"ly-formula\">\r\n    Three-phase generator full-load current: I = S \u00f7 (\u221a3 \u00d7 V)\r\n    <small>S = apparent power in VA; V = line-to-line voltage. This is a useful source-current calculation, not the complete ATS selection method.<\/small>\r\n  <\/div>\r\n\r\n  <p>\r\n    For example, a 30 kVA, 400 V three-phase generator has a calculated full-load current of about 43 A. The final ATS selection must still consider the backed-up load, switching duty, utilization category, motor or transformer inrush, protection coordination and the equipment manufacturer's ratings.\r\n  <\/p>\r\n\r\n  <h3>6. Identify Motor, Pump, Compressor and Transformer Loads<\/h3>\r\n\r\n  <p>\r\n    High-inrush or inductive loads can affect both generator performance and transfer-switch application. Do not select an ATS only from steady-state current when the backed-up feeder includes large motors, pumps, compressors or transformers.\r\n  <\/p>\r\n\r\n  <p>\r\n    Confirm the actual utilization category, permitted load type and switching duty in the ATS technical documentation.\r\n  <\/p>\r\n\r\n  <h3>7. Confirm Short-Circuit and Upstream Protection<\/h3>\r\n\r\n  <p>\r\n    A transfer switch is part of a larger protection system. Its short-circuit withstand or conditional rating, the upstream overcurrent protective device and the installation fault level must be reviewed together.\r\n  <\/p>\r\n\r\n  <p>\r\n    Do not assume that an ATS provides overload, short-circuit or surge protection unless those functions are explicitly included and rated in the specific equipment.\r\n  <\/p>\r\n\r\n  <h2><span class=\"ez-toc-section\" id=\"must-generator-capacity-and-ats-current-rating-be-the-same\"><\/span>Must Generator Capacity and ATS Current Rating Be the Same?<span class=\"ez-toc-section-end\"><\/span><\/h2>\r\n\r\n  <p>\r\n    <strong>No.<\/strong> Generator capacity is commonly expressed in kVA or kW. ATS continuous-current capability is expressed in amperes together with voltage, switching and short-circuit ratings.\r\n  <\/p>\r\n\r\n  <p>\r\n    A generator can supply several separately protected loads through more than one ATS. Conversely, one ATS may serve only a selected critical-load panel even when the generator has additional spare capacity.\r\n  <\/p>\r\n\r\n  <div class=\"ly-buyer\">\r\n    <span class=\"ly-label\">Buyer Meaning<\/span>\r\n    Do not send only \u201cGenerator = 100 kVA\u201d when requesting an ATS quotation. Also provide the system voltage, phase, maximum backed-up load current, important motor loads and intended distribution architecture.\r\n  <\/div>\r\n\r\n  <h2><span class=\"ez-toc-section\" id=\"single-phase-vs-three-phase-generator-ats-selection\"><\/span>Single-Phase vs Three-Phase Generator ATS Selection<span class=\"ez-toc-section-end\"><\/span><\/h2>\r\n\r\n  <p class=\"ly-table-note\">\r\n    Use this table as an initial engineering discussion only. Neutral switching remains project-specific.\r\n  <\/p>\r\n\r\n  <div class=\"ly-table-wrap\">\r\n    <table class=\"ly-stack-table\">\r\n      <thead>\r\n        <tr>\r\n          <th>System<\/th>\r\n          <th>ATS Arrangement to Evaluate<\/th>\r\n          <th>Main Confirmation<\/th>\r\n        <\/tr>\r\n      <\/thead>\r\n      <tbody>\r\n        <tr>\r\n          <td data-label=\"System\">Single-phase<\/td>\r\n          <td data-label=\"Evaluate\">2-pole switching may be used where both line and neutral are required to switch<\/td>\r\n          <td data-label=\"Confirm\">Voltage, conductor arrangement and neutral treatment<\/td>\r\n        <\/tr>\r\n        <tr>\r\n          <td data-label=\"System\">Three-phase with solid neutral<\/td>\r\n          <td data-label=\"Evaluate\">3-pole phase transfer may be possible<\/td>\r\n          <td data-label=\"Confirm\">Grounding, generator neutral and ground-fault protection<\/td>\r\n        <\/tr>\r\n        <tr>\r\n          <td data-label=\"System\">Three-phase with switched neutral<\/td>\r\n          <td data-label=\"Evaluate\">4-pole transfer arrangement<\/td>\r\n          <td data-label=\"Confirm\">Generator neutral, earthing architecture and project requirements<\/td>\r\n        <\/tr>\r\n      <\/tbody>\r\n    <\/table>\r\n  <\/div>\r\n\r\n  <p class=\"ly-table-conclusion\">\r\n    Procurement conclusion: pole count should follow the actual neutral and grounding design, not a simplified phase-count rule.\r\n  <\/p>\r\n\r\n  <h2><span class=\"ez-toc-section\" id=\"open-transition-delayed-transition-or-closed-transition\"><\/span>Open Transition, Delayed Transition or Closed Transition?<span class=\"ez-toc-section-end\"><\/span><\/h2>\r\n\r\n  <div class=\"ly-two-col\">\r\n    <div>\r\n      <h3>Open Transition<\/h3>\r\n      <p>\r\n        The connected source is opened before the alternative source is connected. This break-before-make approach is widely used where a short transfer interruption is acceptable.\r\n      <\/p>\r\n    <\/div>\r\n\r\n    <div>\r\n      <h3>Special Transition Requirements<\/h3>\r\n      <p>\r\n        Delayed, programmed or closed-transition systems require transfer equipment and controls specifically designed for those operating modes. Closed transition introduces source synchronization and paralleling considerations.\r\n      <\/p>\r\n    <\/div>\r\n  <\/div>\r\n\r\n  <p>\r\n    IEC 60947-6-1:2026 includes provisions for automatic transfer switching equipment, bypass\/isolation transfer switching equipment, closed-transition ATSE and stand-alone ATS controllers.<sup><a href=\"#ref-1\">[1]<\/a><\/sup>\r\n  <\/p>\r\n\r\n  <div class=\"ly-warning\">\r\n    <span class=\"ly-label\">Critical-Load Boundary<\/span>\r\n    A fast ATS is not automatically a substitute for a UPS. If the load cannot tolerate the generator-start period or the source-transfer interruption, the continuity architecture must be engineered separately.\r\n  <\/div>\r\n\r\n  <h2><span class=\"ez-toc-section\" id=\"do-you-need-an-ats-device-or-a-complete-ats-panel\"><\/span>Do You Need an ATS Device or a Complete ATS Panel?<span class=\"ez-toc-section-end\"><\/span><\/h2>\r\n\r\n  <p>\r\n    This is an important procurement question. A switchboard manufacturer may need only the transfer device. A generator integrator or project contractor may need a complete assembled cabinet.\r\n  <\/p>\r\n\r\n  <figure class=\"ly-figure\">\r\n    <img loading=\"lazy\"\r\n      src=\"https:\/\/www.cnspd.com\/wp-content\/uploads\/2026\/09\/ats-device-vs-generator-ats-panel-comparison.webp\"\r\n      alt=\"Comparison between an ATS device and a complete generator ATS panel for backup power projects\"\r\n      width=\"1448\"\r\n      height=\"1086\"\r\n      loading=\"lazy\"\r\n      decoding=\"async\">\r\n    <figcaption>\r\n      ATS device versus complete ATS panel. Panel contents are project-specific: breakers, controls, metering, generator-start interface and other functions must be specified rather than assumed to be included.\r\n    <\/figcaption>\r\n  <\/figure>\r\n\r\n  <div class=\"ly-table-wrap\">\r\n    <table class=\"ly-stack-table\">\r\n      <thead>\r\n        <tr>\r\n          <th>Requirement<\/th>\r\n          <th>ATS Device<\/th>\r\n          <th>ATS Panel \/ Cabinet<\/th>\r\n        <\/tr>\r\n      <\/thead>\r\n      <tbody>\r\n        <tr>\r\n          <td data-label=\"Requirement\">Transfer switching equipment<\/td>\r\n          <td data-label=\"ATS Device\">Included<\/td>\r\n          <td data-label=\"ATS Panel\">Included in the assembly<\/td>\r\n        <\/tr>\r\n        <tr>\r\n          <td data-label=\"Requirement\">Enclosure<\/td>\r\n          <td data-label=\"ATS Device\">Provided by the panel builder<\/td>\r\n          <td data-label=\"ATS Panel\">Normally part of the specified assembly<\/td>\r\n        <\/tr>\r\n        <tr>\r\n          <td data-label=\"Requirement\">Incoming \/ outgoing protection<\/td>\r\n          <td data-label=\"ATS Device\">Normally external to the transfer device<\/td>\r\n          <td data-label=\"ATS Panel\">Can be integrated when specified<\/td>\r\n        <\/tr>\r\n        <tr>\r\n          <td data-label=\"Requirement\">Generator-start interface<\/td>\r\n          <td data-label=\"ATS Device\">Must be confirmed by model<\/td>\r\n          <td data-label=\"ATS Panel\">Can be engineered around the generator controller<\/td>\r\n        <\/tr>\r\n        <tr>\r\n          <td data-label=\"Requirement\">Metering \/ indication \/ communication<\/td>\r\n          <td data-label=\"ATS Device\">Product dependent<\/td>\r\n          <td data-label=\"ATS Panel\">Can be included according to project scope<\/td>\r\n        <\/tr>\r\n      <\/tbody>\r\n    <\/table>\r\n  <\/div>\r\n\r\n  <p class=\"ly-table-conclusion\">\r\n    Procurement conclusion: define the supply boundary before requesting a quotation. \u201cATS\u201d can mean only the transfer device or a complete engineered transfer assembly.\r\n  <\/p>\r\n\r\n  <h2><span class=\"ez-toc-section\" id=\"when-are-manual-operation-and-bypass-useful\"><\/span>When Are Manual Operation and Bypass Useful?<span class=\"ez-toc-section-end\"><\/span><\/h2>\r\n\r\n  <h3>Manual Operation<\/h3>\r\n\r\n  <p>\r\n    Manual operation can support commissioning, maintenance, controlled testing and emergency service procedures. The exact method and safe operating conditions depend on the transfer-switch design and manufacturer's instructions.\r\n  <\/p>\r\n\r\n  <h3>Bypass \/ Isolation<\/h3>\r\n\r\n  <p>\r\n    Bypass\/isolation becomes relevant when transfer equipment must be maintained while another controlled power path remains available. It is generally associated with engineered systems where maintainability and availability justify the additional equipment.\r\n  <\/p>\r\n\r\n  <p>\r\n    IEC 60947-6-1:2026 includes dedicated requirements for bypass\/isolation transfer switching equipment.<sup><a href=\"#ref-1\">[1]<\/a><\/sup>\r\n  <\/p>\r\n\r\n  <h2><span class=\"ez-toc-section\" id=\"can-several-ats-units-use-one-generator\"><\/span>Can Several ATS Units Use One Generator?<span class=\"ez-toc-section-end\"><\/span><\/h2>\r\n\r\n  <p>\r\n    Yes, this is possible in a properly engineered system. The generator-start control scheme, contact ratings, isolation and controller logic must be designed for the actual equipment.\r\n  <\/p>\r\n\r\n  <p>\r\n    Schneider Electric \/ ASCO publishes an example in which several transfer switches are connected to a common generator and their engine-start contacts are coordinated so that loss of normal power at a participating transfer switch can request generator start.<sup><a href=\"#ref-4\">[4]<\/a><\/sup>\r\n  <\/p>\r\n\r\n  <div class=\"ly-note\">\r\n    <span class=\"ly-label\">Do Not Generalize the Wiring<\/span>\r\n    The ASCO example proves that multi-ATS generator control is possible; it is not a universal wiring instruction for every manufacturer. Follow the ATS and generator-controller documentation used in the actual project.\r\n  <\/div>\r\n\r\n  <h2><span class=\"ez-toc-section\" id=\"common-generator-ats-selection-mistakes\"><\/span>Common Generator ATS Selection Mistakes<span class=\"ez-toc-section-end\"><\/span><\/h2>\r\n\r\n  <div class=\"ly-table-wrap\">\r\n    <table class=\"ly-stack-table\">\r\n      <thead>\r\n        <tr>\r\n          <th>Wrong Assumption<\/th>\r\n          <th>Possible Project Problem<\/th>\r\n          <th>What to Confirm Instead<\/th>\r\n        <\/tr>\r\n      <\/thead>\r\n      <tbody>\r\n        <tr>\r\n          <td data-label=\"Wrong Assumption\">Every automatic ATS starts a genset<\/td>\r\n          <td data-label=\"Problem\">Backup input never becomes available<\/td>\r\n          <td data-label=\"Confirm\">Engine-start interface and controller logic<\/td>\r\n        <\/tr>\r\n        <tr>\r\n          <td data-label=\"Wrong Assumption\">ATS current should copy generator kVA<\/td>\r\n          <td data-label=\"Problem\">Incorrect transfer-device sizing<\/td>\r\n          <td data-label=\"Confirm\">Actual source current and backed-up load current<\/td>\r\n        <\/tr>\r\n        <tr>\r\n          <td data-label=\"Wrong Assumption\">Three-phase always means one pole arrangement<\/td>\r\n          <td data-label=\"Problem\">Neutral or grounding mismatch<\/td>\r\n          <td data-label=\"Confirm\">Earthing system and neutral treatment<\/td>\r\n        <\/tr>\r\n        <tr>\r\n          <td data-label=\"Wrong Assumption\">Fast switching time equals fast generator recovery<\/td>\r\n          <td data-label=\"Problem\">Unrealistic interruption expectation<\/td>\r\n          <td data-label=\"Confirm\">Full start, stabilization and transfer sequence<\/td>\r\n        <\/tr>\r\n        <tr>\r\n          <td data-label=\"Wrong Assumption\">ATS replaces circuit protection<\/td>\r\n          <td data-label=\"Problem\">Incomplete protection design<\/td>\r\n          <td data-label=\"Confirm\">Breakers, fuses, fault level, earthing and other required protection<\/td>\r\n        <\/tr>\r\n      <\/tbody>\r\n    <\/table>\r\n  <\/div>\r\n\r\n  <h2><span class=\"ez-toc-section\" id=\"where-can-a-compact-leeyee-ats-fit\"><\/span>Where Can a Compact LEEYEE ATS Fit?<span class=\"ez-toc-section-end\"><\/span><\/h2>\r\n\r\n  <p>\r\n    LEEYEE supplies compact low-voltage automatic transfer solutions for applications within the documented ratings of the selected model. A compact ATS can be appropriate where two compatible AC sources must be transferred and the required current, voltage, pole arrangement, utilization category and switching duty are within the product specification.\r\n  <\/p>\r\n\r\n  <p>\r\n    For a generator application, however, the transfer device must not be evaluated in isolation. If the generator normally remains stopped, the system also needs a valid method for requesting generator start and confirming that the backup source has become acceptable.\r\n  <\/p>\r\n\r\n  <div class=\"ly-buyer\">\r\n    <span class=\"ly-label\">Product Boundary<\/span>\r\n    Do not assume that a compact DIN-rail ATS is suitable for large generator plants, closed-transition applications, high-current switchboards or loads requiring uninterrupted power. Match the transfer equipment to the actual project requirements.\r\n  <\/div>\r\n\r\n  <p>\r\n    For current LEEYEE transfer-switch product information, model data and wiring details, review the\r\n    <a href=\"https:\/\/www.cnspd.com\/products\/leeyee-automatic-transfer-switch-solar-backup\/\">LEEYEE automatic transfer switch product page<\/a>.\r\n  <\/p>\r\n\r\n  <h2><span class=\"ez-toc-section\" id=\"which-standards-should-be-checked-for-a-generator-ats-project\"><\/span>Which Standards Should Be Checked for a Generator ATS Project?<span class=\"ez-toc-section-end\"><\/span><\/h2>\r\n\r\n  <p>\r\n    For IEC-oriented projects, the current international transfer-switching standard is <strong>IEC 60947-6-1:2026, Edition 4.0<\/strong>. It covers transfer switching equipment and includes requirements relevant to automatic transfer switching, stand-alone ATS controllers, bypass\/isolation equipment and closed-transition equipment.<sup><a href=\"#ref-1\">[1]<\/a><\/sup>\r\n  <\/p>\r\n\r\n  <p>\r\n    For North American projects, UL Solutions identifies <strong>UL 1008<\/strong> for automatic transfer switches used in emergency systems and optional standby systems.<sup><a href=\"#ref-5\">[5]<\/a><\/sup>\r\n  <\/p>\r\n\r\n  <div class=\"ly-warning\">\r\n    <span class=\"ly-label\">Certificate Scope<\/span>\r\n    A reference to IEC 60947-6-1 or UL 1008 does not prove that a specific ATS model is certified to that standard or edition. For project approval, verify the exact model, certificate or test-report scope, issuing body and edition required by the customer or authority.\r\n  <\/div>\r\n\r\n  <h2><span class=\"ez-toc-section\" id=\"before-ordering-an-automatic-transfer-switch-for-a-generator\"><\/span>Before Ordering an Automatic Transfer Switch for a Generator<span class=\"ez-toc-section-end\"><\/span><\/h2>\r\n\r\n  <p>\r\n    A useful quotation starts with a complete system brief. Sending only \u201c63 A ATS\u201d or \u201c100 kVA generator\u201d leaves important engineering questions unanswered.\r\n  <\/p>\r\n\r\n  <div class=\"ly-checklist\">\r\n    <h3>Generator ATS Project Checklist<\/h3>\r\n\r\n    <div class=\"ly-check-grid\">\r\n      <div class=\"ly-check-item\">Utility voltage and frequency<\/div>\r\n      <div class=\"ly-check-item\">Generator output voltage and frequency<\/div>\r\n      <div class=\"ly-check-item\">Single-phase or three-phase system<\/div>\r\n      <div class=\"ly-check-item\">Single-line diagram if available<\/div>\r\n      <div class=\"ly-check-item\">Earthing and neutral arrangement<\/div>\r\n      <div class=\"ly-check-item\">Maximum continuous backed-up current<\/div>\r\n      <div class=\"ly-check-item\">Motor, pump or transformer loads<\/div>\r\n      <div class=\"ly-check-item\">Generator rated kW \/ kVA and current<\/div>\r\n      <div class=\"ly-check-item\">Generator make and model<\/div>\r\n      <div class=\"ly-check-item\">Generator controller model<\/div>\r\n      <div class=\"ly-check-item\">Remote-start \/ engine-start interface<\/div>\r\n      <div class=\"ly-check-item\">Required pole configuration<\/div>\r\n      <div class=\"ly-check-item\">Maximum acceptable interruption time<\/div>\r\n      <div class=\"ly-check-item\">Required transition method<\/div>\r\n      <div class=\"ly-check-item\">Manual operation requirement<\/div>\r\n      <div class=\"ly-check-item\">Bypass \/ isolation requirement<\/div>\r\n      <div class=\"ly-check-item\">Available fault-current information<\/div>\r\n      <div class=\"ly-check-item\">Upstream protective-device information<\/div>\r\n      <div class=\"ly-check-item\">ATS device or complete ATS panel<\/div>\r\n      <div class=\"ly-check-item\">Enclosure and installation environment<\/div>\r\n      <div class=\"ly-check-item\">Required standard \/ certificate scope<\/div>\r\n      <div class=\"ly-check-item\">Quantity and OEM documentation needs<\/div>\r\n    <\/div>\r\n  <\/div>\r\n\r\n  <section class=\"ly-cta\">\r\n    <h2><span class=\"ez-toc-section\" id=\"need-a-generator-ats-configuration-review\"><\/span>Need a Generator ATS Configuration Review?<span class=\"ez-toc-section-end\"><\/span><\/h2>\r\n\r\n    <p>\r\n      Send the utility voltage, generator voltage, phase, backed-up load current, generator controller model and start-signal information. LEEYEE can help review whether a suitable transfer-switch configuration matches the electrical requirements and identify which conditions still need project confirmation.\r\n    <\/p>\r\n\r\n    <div class=\"ly-cta-action\">\r\n      <button\r\n        type=\"button\"\r\n        class=\"leeyee-about-btn-light leeyee-site-popup-btn\"\r\n        aria-label=\"Request a Quote\">\r\n        <span class=\"w-btn-label\">Request a Quote<\/span>\r\n      <\/button>\r\n    <\/div>\r\n  <\/section>\r\n\r\n  <h2><span class=\"ez-toc-section\" id=\"frequently-asked-questions-about-generator-ats-systems\"><\/span>Frequently Asked Questions About Generator ATS Systems<span class=\"ez-toc-section-end\"><\/span><\/h2>\r\n\r\n  <div class=\"ly-faq\">\r\n\r\n    <details>\r\n      <summary>Does an ATS automatically start the generator?<\/summary>\r\n      <div class=\"ly-faq-answer\">\r\n        Some ATS controllers provide engine-start contacts or another generator-start interface. Other transfer devices only switch between sources that are already available. Confirm the ATS output and generator-controller input before assuming automatic generator starting.\r\n      <\/div>\r\n    <\/details>\r\n\r\n    <details>\r\n      <summary>What signal does an ATS send to a generator?<\/summary>\r\n      <div class=\"ly-faq-answer\">\r\n        A relay or dry-contact start signal is common, but the logic is equipment-specific. Schneider Electric \/ ASCO documentation shows both close-to-start and open-to-start arrangements. Use the wiring diagrams for the actual ATS and generator controller.\r\n      <\/div>\r\n    <\/details>\r\n\r\n    <details>\r\n      <summary>Does the ATS transfer immediately when the generator starts?<\/summary>\r\n      <div class=\"ly-faq-answer\">\r\n        Not necessarily. The generator source should first meet the ATS controller's acceptable voltage and, where applicable, frequency conditions. A transfer delay may then allow the source to stabilize before the load is connected.\r\n      <\/div>\r\n    <\/details>\r\n\r\n    <details>\r\n      <summary>How long does an ATS take to transfer to generator power?<\/summary>\r\n      <div class=\"ly-faq-answer\">\r\n        Total outage-to-generator restoration time depends on the start delay, generator starting and stabilization, source-acceptance conditions, transfer delay and ATS switching operation. The switch's transfer-time specification is only one part of that sequence.\r\n      <\/div>\r\n    <\/details>\r\n\r\n    <details>\r\n      <summary>Why does the generator keep running after utility power returns?<\/summary>\r\n      <div class=\"ly-faq-answer\">\r\n        Many systems use a retransfer delay before returning the load to utility and a separate generator stop or cooldown delay after the load has transferred back. Exact timing is controller- and project-specific.\r\n      <\/div>\r\n    <\/details>\r\n\r\n    <details>\r\n      <summary>Should generator kVA equal the ATS ampere rating?<\/summary>\r\n      <div class=\"ly-faq-answer\">\r\n        No. Generator capacity and ATS continuous-current rating are different electrical quantities. Calculate the available source current, then verify the actual backed-up load, switching duty, inrush characteristics, short-circuit requirements and manufacturer ratings.\r\n      <\/div>\r\n    <\/details>\r\n\r\n    <details>\r\n      <summary>Do I need a 2P, 3P or 4P ATS for a generator?<\/summary>\r\n      <div class=\"ly-faq-answer\">\r\n        Pole selection depends on the conductor arrangement and whether the neutral must be switched. Neutral treatment is linked to the grounding system, generator neutral arrangement and ground-fault protection design, so the actual project schematic should determine the final choice.\r\n      <\/div>\r\n    <\/details>\r\n\r\n    <details>\r\n      <summary>Can one generator supply several ATS units?<\/summary>\r\n      <div class=\"ly-faq-answer\">\r\n        Yes, when the power distribution and generator-start control scheme are engineered for it. Do not simply parallel control wiring unless the ATS and generator manufacturers' documentation permits that arrangement.\r\n      <\/div>\r\n    <\/details>\r\n\r\n    <details>\r\n      <summary>Do I need an ATS device or a complete generator ATS panel?<\/summary>\r\n      <div class=\"ly-faq-answer\">\r\n        A panel builder may only need the transfer device. A generator integrator or contractor may need a complete enclosure with protection, terminals, controls, indication and generator interface. Define the supply boundary before requesting a quotation.\r\n      <\/div>\r\n    <\/details>\r\n\r\n    <details>\r\n      <summary>When should bypass\/isolation be considered?<\/summary>\r\n      <div class=\"ly-faq-answer\">\r\n        Bypass\/isolation is relevant when the transfer equipment needs maintenance while another controlled supply path must remain available. Whether it is required depends on the availability target, project architecture and applicable requirements.\r\n      <\/div>\r\n    <\/details>\r\n\r\n    <details>\r\n      <summary>Is a fast ATS the same as a UPS?<\/summary>\r\n      <div class=\"ly-faq-answer\">\r\n        No. An ATS transfers a load between sources; it does not provide stored energy during the generator-start period. Loads that cannot tolerate the required interruption may need a UPS or another continuity solution as part of the overall system.\r\n      <\/div>\r\n    <\/details>\r\n\r\n  <\/div>\r\n\r\n  <section class=\"ly-related\">\r\n    <h2><span class=\"ez-toc-section\" id=\"related-ats-reading\"><\/span>Related ATS Reading<span class=\"ez-toc-section-end\"><\/span><\/h2>\r\n\r\n    <p>\r\n      For general ATS fundamentals, source-transfer basics and broader ATS selection, see\r\n      <a href=\"https:\/\/www.cnspd.com\/what-is-an-automatic-transfer-switch-how-ats-works-how-to-choose\/\">What Is an Automatic Transfer Switch? How ATS Works &amp; How to Choose<\/a>.\r\n    <\/p>\r\n\r\n    <p class=\"ly-small\">\r\n      This page intentionally focuses on generator start coordination, utility-to-generator transfer timing, generator ATS sizing, neutral switching and project procurement so that it does not duplicate the broader ATS guide.\r\n    <\/p>\r\n  <\/section>\r\n\r\n  <section class=\"ly-refs\">\r\n    <h2><span class=\"ez-toc-section\" id=\"references\"><\/span>References<span class=\"ez-toc-section-end\"><\/span><\/h2>\r\n\r\n    <ol>\r\n      <li id=\"ref-1\">\r\n        International Electrotechnical Commission (IEC).\r\n        <strong>IEC 60947-6-1:2026, Low-voltage switchgear and controlgear \u2014 Part 6-1: Multiple function equipment \u2014 Transfer switching equipment.<\/strong>\r\n        Edition 4.0.\r\n        Official IEC information:\r\n        <a href=\"https:\/\/webstore.iec.ch\/en\/publication\/90494\" rel=\"noopener noreferrer\" target=\"_blank\">IEC 60947-6-1:2026<\/a>.\r\n      <\/li>\r\n\r\n      <li id=\"ref-2\">\r\n        Cummins Power Generation.\r\n        <strong>T-011 Transfer Switch Application Manual.<\/strong>\r\n        Used for source monitoring, start delay, transfer delay, retransfer delay, generator stop\/cooldown delay, continuous-current selection and neutral-switching application principles.\r\n        Official document:\r\n        <a href=\"https:\/\/www.cummins.com\/sites\/default\/files\/2024-08\/t011-Transfer-switch-application-manual.pdf\" rel=\"noopener noreferrer\" target=\"_blank\">Cummins Transfer Switch Application Manual<\/a>.\r\n      <\/li>\r\n\r\n      <li id=\"ref-3\">\r\n        Schneider Electric \/ ASCO Power Technologies.\r\n        <strong>Engine Start Signal and Transfer Switch Technical Guidance.<\/strong>\r\n        Used for engine-start contact arrangements and model-dependent start-control logic.\r\n        Official technical information:\r\n        <a href=\"https:\/\/www.se.com\/us\/en\/faqs\/FAQ000192009\/\" rel=\"noopener noreferrer\" target=\"_blank\">ASCO Engine Start Technical FAQ<\/a>.\r\n      <\/li>\r\n\r\n      <li id=\"ref-4\">\r\n        Schneider Electric \/ ASCO Power Technologies.\r\n        <strong>Multiple Transfer Switches With a Common Generator.<\/strong>\r\n        Used as an equipment-specific example showing that several ATS units can coordinate generator-start contacts in an engineered system.\r\n        Official technical information:\r\n        <a href=\"https:\/\/www.se.com\/us\/en\/faqs\/FAQ000239961\/\" rel=\"noopener noreferrer\" target=\"_blank\">ASCO Multiple ATS \/ Common Generator FAQ<\/a>.\r\n      <\/li>\r\n\r\n      <li id=\"ref-5\">\r\n        UL Solutions.\r\n        <strong>Switch Certification and Evaluation Services.<\/strong>\r\n        Identifies UL 1008 for automatic transfer switches used in emergency and optional standby systems.\r\n        Official UL information:\r\n        <a href=\"https:\/\/www.ul.com\/services\/switch-certification-and-evaluation-services\" rel=\"noopener noreferrer\" target=\"_blank\">UL Transfer Switch Information<\/a>.\r\n      <\/li>\r\n    <\/ol>\r\n  <\/section>\r\n\r\n  <script>\r\n    document.addEventListener('DOMContentLoaded', function () {\r\n      var aboutPopupButtons = document.querySelectorAll('.leeyee-site-popup-btn');\r\n\r\n      aboutPopupButtons.forEach(function (button) {\r\n        button.addEventListener('click', function () {\r\n          var realPopupTrigger = document.querySelector('.w-popup.ush_popup_1 .w-popup-trigger');\r\n\r\n          if (realPopupTrigger) {\r\n            realPopupTrigger.click();\r\n          } else {\r\n            window.open('https:\/\/www.cnspd.com\/contact\/', '_blank', 'noopener'); \r\n          } \r\n        }); \r\n      }); \r\n    });\r\n  <\/script>\r\n\r\n<\/article>\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>An automatic transfer switch for a generator backup system should not be selected as an isolated switch. The ATS must match the utility source, generator output, generator controller, backed-up load, phase and neutral arrangement, transfer sequence, protection design and project requirements. This guide is for generator-set integrators, ATS panel builders, electrical contractors, industrial and commercial&#8230;<\/p>","protected":false},"author":18,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[490,1,422],"tags":[],"class_list":["post-31023","post","type-post","status-publish","format-standard","hentry","category-isolator-switching","category-news","category-industry-news"],"acf":[],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v28.3 - https:\/\/yoast.com\/product\/yoast-seo-wordpress\/ -->\n<title>Automatic Transfer Switch for Generator: ATS Selection Guide<\/title>\n<meta name=\"description\" content=\"Learn how to select an automatic transfer switch for generator backup systems, including start signals, transfer delays, ATS sizing, neutral switching, generator controllers, panels and OEM project requirements.\" \/>\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\/it\/generator-automatic-transfer-switch\/\" \/>\n<meta property=\"og:locale\" content=\"it_IT\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"Automatic Transfer Switch for Generator: ATS Selection Guide\" \/>\n<meta property=\"og:description\" content=\"Learn how to select an automatic transfer switch for generator backup systems, including start signals, transfer delays, ATS sizing, neutral switching, generator controllers, panels and OEM project requirements.\" \/>\n<meta property=\"og:url\" content=\"https:\/\/www.cnspd.com\/it\/generator-automatic-transfer-switch\/\" \/>\n<meta property=\"og:site_name\" content=\"Surge Protector, Surge Arrestor, Isolating Switch - LEEYEE\" \/>\n<meta property=\"article:published_time\" content=\"2026-09-15T01:02:26+00:00\" \/>\n<meta property=\"article:modified_time\" content=\"2026-09-15T01:04:11+00:00\" \/>\n<meta name=\"author\" content=\"Devin Ling\" \/>\n<meta name=\"twitter:card\" content=\"summary_large_image\" \/>\n<meta name=\"twitter:label1\" content=\"Scritto da\" \/>\n\t<meta name=\"twitter:data1\" content=\"Devin Ling\" \/>\n\t<meta name=\"twitter:label2\" content=\"Tempo di lettura stimato\" \/>\n\t<meta name=\"twitter:data2\" content=\"17 minuti\" \/>\n<script type=\"application\/ld+json\" class=\"yoast-schema-graph\">{\"@context\":\"https:\\\/\\\/schema.org\",\"@graph\":[{\"@type\":\"Article\",\"@id\":\"https:\\\/\\\/www.cnspd.com\\\/generator-automatic-transfer-switch\\\/#article\",\"isPartOf\":{\"@id\":\"https:\\\/\\\/www.cnspd.com\\\/generator-automatic-transfer-switch\\\/\"},\"author\":{\"name\":\"Devin Ling\",\"@id\":\"https:\\\/\\\/www.cnspd.com\\\/#\\\/schema\\\/person\\\/f49dbafe62c5b47100ad2d9f88af92d3\"},\"headline\":\"Automatic Transfer Switch for Generator Backup Power Systems\",\"datePublished\":\"2026-09-15T01:02:26+00:00\",\"dateModified\":\"2026-09-15T01:04:11+00:00\",\"mainEntityOfPage\":{\"@id\":\"https:\\\/\\\/www.cnspd.com\\\/generator-automatic-transfer-switch\\\/\"},\"wordCount\":3693,\"articleSection\":[\"Isolator &amp; 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