Petersen Coil and Capacitive Charge Current

In a single phase ground fault the insulation for the other two phases will have to handle full phase to phase voltage.

The Petersen coil alone cannot detect the faulty phase. The coil is a connected on the neutral of the network. Most of the times theis neutral is created using a transformer.

I have a 20 kV system that uses coil compensation for ground faults. The system also detects the faulty line using homopolar current transformers for each circuit connected to the bus system. The coil is there just to limit the fault current. When a fault occurs the detection system (it is a Trench system) disconects the faulty line and the powerline maintenance team goes out to find the fault. Most of the network consists of overhead lines so finding a fault isn't quite difficult.