Study On The Corona Characteristic And Repairing Technique For Large Generator

The insulation is the key factor for a generator's reliability and durability, and by tracking and predicting its early faults, troubles can be prevented and correspondent measures can be taken. It is a important link for power plant to check out and deal with the faults. Considering the characteristics of insulation and requirements of corona protecting, and by researching the characteristics of the early faults of the generator, this paper presents the on site methods to deal with the corona of the generator.This paper studies the structure of the generator' insulation. There are two kinds of craft in main insulation: few and rich resin mica system. The new type of insulation' function is better than before as a result of continuous optimizing the insulation structure of large generators and improving manufacturing craft . A great progress is made in corona preventing structure of the bar and electrical erosion of the slot. The new technology such as the main insulation with semi-conductor coating and bar fixed in sot with semi-conductor side pack offers a good premise to decrease the failures in a generator.This paper studies the corona protecting structure of the generator and the discharge characteristics of the all kind of PD, such as discharge in slot, and corona in end winding. The function and applications are studied and compared for all kinds of PD monitoring systems both domestic and overseas. According to the taken signal, this method can be divided into non-electrical and electrical measurement, and the latter especially ERA is widely applied on on-line monitoring. All kinds of the PD signals are different, so the signals' characteristics must be recognized and analyzed. The techniques such as broadband sampling and digital analyzing combined with hardware and software against interference is adopted widely now, and the latter is applied more. The structure of PDM- II PD monitoring system is analyzed by taking a case which has been applied in GZB Power Plant No. 19.This paper studies how to deal with the phenomenon of generator' corona. Proving by practical cases, the paper shows that most of the corona in generator can be treated with effectually, but the right materials and methods must be taken. Such on site methods as replacing protecting material, air gap short-circuit between bars and partial repair are proved feasible against corona.