Analysis of the insulated power-grid transient behavior after faulted phase tripping

The common cases of a nonselective operation of the phase to ground fault protection in the insulated power grids, which utilize inductive sensors for a voltage unbalance indication, are explained by ferroresonant processes in voltage transformers of healthy drains. This paper deals with phase to ground faults simulations in a known grid, that provide information about possible nonselective phase to ground faults protection operation.