Feb. 28, 2022
By summarizing the common faults of generators in thermal power plants, we can find out the characteristics of generator faults by summarizing the operation rules of generators, and provide basis and reference for the maintenance and troubleshooting of generators.
The common failures of generators are as follows:
(1) leakage of water-cooled stator windings, domestic and imported generating sets mostly adopt hydrohydrogen cooling mode. Water - cooled stator winding water leakage is a common fault. Severe cases often lead to grounding and phase short circuit accidents. The main causes of such accidents are design, process and materials. The main means of checking the leakage of stator windings should be the air tightness test method (first filling compressed air with nitrogen or freon pressure of 0.1 mpa, and finally reaching the rated pressure, using soapy water or halogen leak detector to detect the leakage point). When airtight method is used in the field, the water in the water loop should be removed and dried before the test to eliminate stagnant water.
(2) water-cooled stator and rotor winding blockage is also a common fault.The main reason for failure is that the cold water quality is not up to standard, the formation of precipitated oxide blockage, or there is foreign matter (rubber pad, asbestos mud or even rags). Stay in the water loop. The fundamental measure to eliminate foreign body blockage is to strictly control motor assembly and maintenance process and corresponding inspection system. In addition, backwash and flow tests shall be carried out in accordance with relevant standards and procedures.
(3) Phase short circuit caused by end coil failure. The main reasons of short circuit accident are unreasonable design of end fixed structure, careless insulation process, poor welding process of
copper wire, unqualified material selection and inspection, etc. The high humidity of hydrogen in machines, which is not up to standard, is often the cause of accidents.
(4) Short circuit and grounding fault between turns of rotor windings is a common fault, which is caused by thermal deformation or high operating temperature of rotor windings, resulting in insulation damage between turns. The generator operation regulations issued by the Ministry of Electric Power stipulates that when the rotor winding of a hidden pole generator is grounded at a certain point, the location and nature of the fault should be found out immediately. If it is a stable metal grounding, the rotor-cooled generator with a capacity of 100 MW or more should be shut down as soon as possible. For generators below 100MW, a two-point grounding protection device should be connected to the excitation circuit, and as soon as possible to arrange maintenance shutdown.
(5) Axial voltage of turbogenerator set; The axial voltage is mainly caused by the static charge of the low pressure cylinder of the turbine. Magnetic circuit asymmetry during generator manufacturing or operation; The pulsation component of the static excitation system; Monopole potential caused by short circuit between turns of rotor winding.
Guangxi Dingbo Power Equipment Manufacturing Co., Ltd. established in 2006, is an manufacturer of diesel generator in China, which integrates design, supply, commissioning and maintenance of diesel generator set. Product covers Cummins, Perkins, Volvo, Yuchai, Shangchai, Deutz, Ricardo, MTU, Weichai etc. with power range 20kw-3000kw, and become their OEM factory and technology center.
Jun. 24, 2022
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