Turn-to-turn fault protection technique for synchronous machines without additional voltage transformers

This paper presents a novel protection technique for the detection of inter-turn faults in synchronous machines. It is based on the calculation of voltage in the stator windings from the usual phases and neutral voltage, typically available in all generator protection relays. The existing turn-to-turn protection mechanisms require additional voltage transformers. The main contribution of this technique is that it can be implemented without using any additional voltage transformers. This technique has been successfully tested in a special synchronous machine with taps in the stator windings, where turn-to-turn faults have been created.