The effect of current delay angle on tripping of residual current devices

Power electronics converters applied in domestic or similar installations may utilize current delay (phase) angle control to change the level of transferred power. Due to application of such types of converters, earth fault current in the installation may be strongly distorted. The current distortion level depends on a value of current delay angle. This delay angle also influences the tripping threshold of residual current devices. In this paper, computer modelling of the impact of current delay angle on behaviour of residual current devices is conducted. Results of laboratory tests of the tripping of residual current devices are discussed. Conclusions regarding electrical safety are presented as well.