Technical Guides

SPD Structure and OEM Selection Guide MOV and GDT are both used for surge protection, but they operate differently. An MOV progressively limits voltage. A GDT or spark gap remains…

Type 1 SPD Engineering and OEM Guide Published: July 14, 2026 Technical review: LEEYEE SPD Engineering Team Standards reviewed: IEC 61643-11:2025 and IEC 61643-12:2020 When a project already requires a…

Single-Phase SPD Buyer & OEM Selection Guide The difference between a 1P+N SPD and a 2P SPD cannot always be determined from the product name. For a correct single-phase distribution-board…

TN-S System · Three-Phase Distribution · OEM Selection TN-S SPD Wiring at a Glance In a three-phase TN-S system, the surge protective device is connected in parallel with L1, L2,…

SPD Procurement Guide · Samples · Trial Orders · OEM MOQ What is the minimum order quantity (MOQ) for a surge protective device (SPD) manufacturer? Can an OEM buyer order…

Industrial Control Panel Guide VFD surge protection normally starts on the incoming power side of the variable frequency drive, not on its PWM motor output. A correctly selected Type 2…

A surge protective device that has turned black, melted, smoked, cracked or burned has experienced severe electrical or thermal stress. The visible damage confirms that a serious event occurred, but…

The most common causes of SPD failure are repeated surge stress, temporary overvoltage, incorrect Uc or Ucpv selection, wiring errors, unsuitable backup protection, excessive temperature, moisture, and the use of…

Pluggable SPD Replacement Guide In many pluggable SPDs, the removable protection module can be replaced without disconnecting and rewiring the base—but only when the existing base is undamaged and the…

Commercial Distribution Board Wiring Guide This single phase surge protector wiring diagram guide explains how panel builders should connect 1P+N and 2P SPDs, identify L, N and PE terminals, coordinate…