Abstract: The rotor inter-turn short circuit fault is one of the common faults occurring to the generator. The bearing vibration climbing happened to a 660 MW turbo-generator in working state during the process of load increase, so according to the correlation between bearing vibration and excitation current, the phase change and rise time of bearing vibration and the oil temperature change of sealing pads, the paper employed repetitive surge oscilloscope and rotor inter-pole voltage method to judge that the rotor winding has inter-turn short circuit faults.After disassembling the rotor, it found that inter-turn insulation at the corner of the end of the No.4 coil was displaced. Therefore, double-layered the rotor inter-turn insulation was adopted to make the unit put into normal operation again.

    Key words: generator; rotor winding; inter-turn short circuit; repetitive surge oscilloscope