Eaton, SD Surge Suppressor Unit 32 V dc, 22V ac Maximum Voltage Rating 20 kA Maximum Surge Current Surge Protection

Eaton MTL Ultra Slim Loop Surge Protector - SD Series

The SD series of surge protector units from Eaton has an ultra-slim design for protecting electrical equipment against surges on control loop cabling. The SD surge protection devices use a hybrid protection circuit, combining sold state electronics and a gas-filled discharge tube (GDT). This combination is designed for exceptionally low line resistance and adds only a small voltage drop to the system whilst providing surge protection up to 20kA.

Surge Protection Devices, SPDs (DIN-rail)

Voltage surges, often referred to as spikes or transients are typically caused by switching of fluorescent lights, fuses blowing or nearby lightning activity. The worst voltage spikes are usually caused by lightning strikes and can reach up to 6000V, with current surges of over 3000A. The maximum size of the let-through voltage and current inrush depends on the location within the building's wiring system. BS7671: 2011 Amendment 1 Sections 443 and 534 cover risk assessment and provides guidance on protection of electronic equipment for installation engineers to follow. The fullest information on lightning and surge protection comes from the BSEN 62305 series of standards.