EFxPTOC is designed for protection and clearance of earth faults in distribution and sub-transmission networks where the neutral point is isolated or earthed via a resonance coil or through low resistance. It also applies to solidly earthed networks and earth-fault protection of different equipment connected to the power systems, such as shunt capacitor bank or shunt reactors and for backup earth-fault protection of power transformers.
Many applications require several steps using different current start levels and time delays. EFxPTOC consists of three different protection stages.
- Low EFLPTOC
- High EFHPTOC
- Instantaneous EFIPTOC