Design of a Type B Residual Current Device for Fault Leakage Current Detection

Residual current device (RCD) is an effective fault leakage current detection and protection device. The international standard IEC 60755 classifies RCDs into four types in accordance with their sensitivity and the shape of fault leakage current. According to IEC 60755, each type of RCD has its own test procedure and guide for suitable demonstration circuits. Many commercial RCD products cannot meet the RCD specifications in some of the demonstration circuits. Based on the magnetic modulation principle, the work proposes a novel type B RCD detector suited most for power electronic installations to meet IEC 60755 specifications. Compared with the commercial products, the performance of the presented RCD can be verified. The proposed methodology may serve as valuable references for RCD applications.