IEC 61643 SPD: The Guide to Surge Protection Standards
Surge Protective Device IEC 61643 SPD: Everything You Need to Know Surge protection is fundamental for any electrical system in this day and age. The IEC 61643 SPD Standard defines the performance and testing parameters of Surge Protective Devices (SPDs) intended for use in low-voltage electric power installations. This helps mitigate the damages incurred from over-voltages resulting from lightning, switching operations, and other such activities. Understanding IEC 61643 Standards IEC 61643 is the international standard for surge protective devices (SPDs), which is split into several parts: • IEC 61643-11: Deals with SPDs for the power supply systems. • IEC 61643-21: Deals with the SPDs for telecommunication and data lines. • IEC 61643-31: Contains the standard requirements for certain applications of direct current power, which includes photovoltaic (solar) systems. These parts establish standards for testing, classification, and performance requirements of SPDs for diverse applications. SPD Classification Under IEC 61643 SPDs are further divided into three categories according to their functional application and level of protection provided: • Primarily intended to guard against direct lightning strikes. • Installed at the main service entrance. • Subjected to impulse current (Iimp) testing. • Example: Class I SPD IEC 61643. • Prevents damage from indirect lightning strikes and switching surges. • Installed at the distribution boards. • Unit is tested with nominal discharge current (In). • Example: Class II SPD IEC 61643. • Protects the point of use for sensitive equipment. • Requires upstream Type2 protection. • Example: Class III SPD IEC 61643. Key Technical Parameters of IEC 61643 SPD Knowing the technical details of an SPD is vital in choosing one. These are the critical parameters to look out for: • Maximum Discharge Current (Imax) – the highest current the SPD is intended to be exposed to. • Nominal Discharge Current (In) – The ...
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