Phenomena:
(1) The alarm bell rings and the “Generator Stator Grounded” light plate lights up. ?
(2) The voltmeter of the stator circuit insulation monitoring device has an indication. ?
(3) The water leak alarm device can work. ?
(4) When the primary fuse of the voltage transformer for protection is blown and the latch fails, the stator grounding protection will not work properly. Pay attention to the distinction.
(5) When the fundamental wave is triggered, the generator-transformer group is triggered and stopped. ?
(6) Third harmonic action signaling.
Treatment: ?
(1) The unit trips, checks the power switching situation of the installation and treats it as if the generator had tripped. Place the generator-transformer group for maintenancet contact maintenance to check the cause of the grounding. ?
(2) If the generator does not trip (the ground protection signal is in the signal position), check the voltmeter of the stator circuit insulation monitoring device and Determine whether a grounding phenomenon occurs based on the operating conditions. ?
(3) Contact secondary team personnel to measure the secondary opening voltage of the TV generator and check the protection device. If the zero sequence voltage indication is higher than that of other units, it means that the unit is effectively grounded, and the relevant duty manager and plant executives should be informed to request shutdown . ?
(4) Wear insulating boots to make a complete inspection of the generator body and lead wires to see if the primary and secondary plugs of the TV areloose, causing false signals, and check the neutral point of the generator in relation to the main network. transformer Carry out a detailed inspection of the output wires and high voltage side housing area of the high voltage transformer to see if there is obvious grounding phenomenon (such as water leakage, etc. causing grounding). ?
(5) If it is the third harmonic grounding, care should be taken to check whether it is a protection malfunction. ?
Causes of generator stator grounding:
Stator coil leakage or water ingress causing degradation insulation; vibrations generated during operation of conductive wires cause damage to insulation; Condensation in the machine causes grounding; oil leaking from the bearing leads to insulation degradation; single phase earthingwinding of the low voltage side of the main transformer or the high voltage side winding of the transformer of the high voltage installation, etc. .