Phase Failures During Starting of High Power In-House Loads

The operation of sections of in-house loads and auxiliary equipment of a Bulgarian power station in fault conditions during starting procedures that take place after completion of planned annual repairment is studied. The considered fault conditions are single-phase open circuit, double-phase open circuit and single-phase open circuit with earth fault. During starting procedures sections are not fully loaded. Based on results it can be seen that imbalances caused by phase failures and open circuit faults during starting are practically similar as whenever they are fully loaded. Thus, the respective protection devices trip accordingly.