GROUND FAULT PROTECTIVE APPARATUS OF FIELD WINDINGS

摘要

A resistor, a DC source and a current converter are connected in series between one terminal of the field winding and the ground. When a ground fault occurs on the field winding, it is detected by the output of a voltage detector connected across the resistor or the output of the current converter, and an alarm device is operated. At the same time, another resistor is connected between the other terminal of the field winding and the current converter through a switch, and the magnitude of the ground fault IS calculated by the outputs of the voltage detector and of the current converter before and after closure of the switch. According to this invention the operation of the generator is continued when the fault is light but the generator is immediately disconnected from the power system when the fault is severe thus decreasing the disturbance of the power system in case of a light fault but positively protecting the generator against heavy fault.