Time-Current Tripping Characteristics of RCDs for Sinusoidal Testing Current

Low-voltage electrical installations are verified initially - before being put into operation, as well as periodically - during their utilization. According to the IEC standards, the scope of the verification includes measurements of both the tripping current and the disconnection time of residual current devices (RCDs). Experiences in RCDs testing show that disconnection times of two or more similar RCDs can be quite different. Significant differences in disconnection times are also noticed for the same RCD in the consecutive trials. This paper presents the result of the test of twenty-four RCDs. Their real tripping current, as well as disconnection time, have been verified. Differences in the obtained values of disconnection times are commented, and their possible sources are indicated.