Residual Current Devices

Chapter 5: Protection against fire

Abstract

Leakage currents which flow from line conductor to earth, through the resistive medium, generate heat, and in some circumstances, may cause a fire. To prevent the flow of a high-value leakage current for a long time, a residual current device may be used as a protective one. The principle of fire protection with the use of the residual current device is presented in this chapter. The criterion of the effective protection is the rated residual operating current of the residual current device. Usually, in 230/400 V power systems, it should not exceed 300 mA. However, in three-phase circuits, some types of leakage currents may not be detected. No reaction of the residual current device may also occur ...