| As the basic equipment of the production of electric energy, the generator has great effect on the safety and stabilization of the whole electric system. The development of on-line monitor of generator and the faults finding of generators promptly and effectively has gradually become an important method which ensures the safe and reliable running of electricity generation equipment.In every components of the large turbo-generator, the rotor endures great mechanical stress and thermal load because it is in the state of high velocity rotating. So the trouble shooting of the rotor section becomes very important. Due to the bad processing craft during the manufacture and the affection of all kinds of machinery during running, there often arises contact between coils in the rotor winding of the large turbo-generator, i.e., it causes the short circuit between coils of rotor windings. The trouble of short circuit between coils of rotor windings in the running on site is the normal one of all kinds of troubles of generator and is also one of the reasons that affect the safety running.Firstly, this text analyses the factors which cause the trouble of short circuit between coils of the rotor winding of large turbo-generator. In the aspects of manufacture and operation, it points out that the trouble of short circuit between coils of rotor windings is caused mainly by the bad processing craft and the damage of insulation. This text also researches all kinds of internal and international traditional check methods at present about the trouble of short circuit between coils and sums up its characteristics and shortcomings.Secondly, this text analyses the mechanical theory and magnetic movements of the trouble of short circuit between coils of rotor windings. It also analyses the distribution of magnetic movements in the normal and faulted state of generator in details and sets forth the research of all kinds of diagnose methods and the existing problems in theory.From the theoretic and practical analyses of diagnosing the short circuit fault between coils of rotor windings of turbo-generator, we get the information that the differential coil move measurement is highly believable because it is free of the affection of the external conditions and the position of the short circuit fault point between coils. Although air gap coil detect method can be used only in the generators without loading and three-phase short circuit. In the condition of generators with load, it requires the rotor to be measured in the state of rotating because the affection of the armature reaction test is not obvious. This causes the rotor can not be applied when it is finished. But this feature fits jolly for the test when the product of the machine manufacture factory has finished. The test personnel of our department have made a series of test research using conventional oscillogram and self-made differential coil and gained valuable experience. Especially the publishment of JB/T8446THE DIFFERENTIATION METHOD OF SHORT CIRCUIT BETWEEN ROTOR TURNS OF NON-SALIENT POLE TYPE SYNCHRO-GENERATOR indicated that the wave shaped method was taken as the final differential method. And the GB/T7064-2002criteria also requires doing this test. The finished rotors imported by our factory from ALSTOM take the wave shaped note as the note come with the machine.Combined with the producing practice and based on the technical standard of our factory, our company purchased HD8085 turbo-generator rotor winding turn-to-turn short circuit test... |
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