Chapter 10 - Residual current devices in circuits with surge protective devices

Abstract

Surge protective devices are inseparable elements of electrical installations containing electronic equipment sensitive to overvoltages coming from switching processes in installations or from lightning discharges. If residual current devices are planned to be installed in a circuit, their coordination with surge protective devices should be analyzed in detail. Residual current devices may be located downstream or upstream of the surge protective devices. However, the latter solution requires the application of special types of residual current devices (delayed type, increased immunity to the surge current). Moreover, the surge protective devices configuration (4+0 or 3+1) is also important. This chapter presents the effect of various coordinations of the aforementioned devices on the reliability of supply in electrical installations. Selected configurations of the surge protective devices are also discussed with reference to the residual current devices’ behavior as well as the effectiveness of protection against electric shock.