scope:

This application guide applies to thyristor surge protective device (thyristor SPD) components used in systems with voltages up to 1000 V rms or 1200 V dc. These components are designed to limit overvoltages and divert surge currents by voltage clamping and crowbarring (switching to a low impedance) actions. Although telecommunication circuits are the main application of thyristor SPDs, this guide will also provide useful information for other protection applications.

This guide is intended to complement the IEEE Standard Test Specification for Thyristor Diode Surge Protective Devices (IEEE C62.37-1996). The definitions used in these two standards are the same.

This publication contains information on

a) Basic function and component description 

b) General terms and definitions

c) Electrical environment

d) Parameter interpretation and application

e) Example designs

f) SPD technology comparison

When used in conjunction with IEEE Std C62.37-1996, this guide will give the user guidance in interpreting its specifications and in selecting the correct product.