The RCC ground fault neutralizer - a novel scheme for fast earth-fault protection

The RCC (Residual Current Compensation) Ground Fault Neutralizer developed by Swedish Neutral defines new benchmarks for resonant grounded medium and high voltage grids. For the first time, safe arc extinguishing is possible also on cable faults. Speed is the most essential aspect of protection, trying to satisfy crucial conditions for personal safety and fire prevention. With a total response time of less than 3 cycles — independent of the actual fault location — the RCC Ground Fault Neutralizer offers a new quality in protection (Fig. 1). In many countries it has been practice to maintain full feeder operation during tracing of sustained earth-faults. Along with the increasing cabling of medium voltage networks now also the uncompensated residual has grown substantially, multiplying the risk for collateral damages during time consuming fault tracings. In order to stop this development Swedish authorities already in 1987 introduced compelling claims for feeder tripping within 5 sec. The RCC Ground Fault Neutralizer now provides truly personal safe operation on sustained faults. Even in Sweden, being so aware of security, full-scheme protected networks are again allowed to maintain operation during fault tracing.