On-line Turn-to-Turn Protection Method of the Synchronous Machines Field Winding

Turn-to-turn faults are quite common in the synchronous generator field winding, especially in the turbo-generator types. This condition may be caused by either the double- ground fault of the winding or by a lack of insulation between adjacent turns. This paper presents a new on-line protection method for turn-to-turn faults in field windings of synchronous machines with static excitation system. The proposed method is based on the comparison of the measured excitation current with the theoretical excitation current calculated from the stator voltages and currents for the actual operation point. The method has been validated by experimental results using a special laboratory synchronous machine.