Ultra-low frequency withstand voltage test method for high voltage motor
Ultra-low frequency withstand voltage test method for high voltage motor The operation method of the ultra-low frequency withstand voltage test for the high-voltage motor is similar to that of the cable. This article focuses on different places. Dear Customer: China Extract Powder For Use As Dietary Supplement Extract Powder, Extract Powder Manufacturer Shaanxi Kang New Pharmaceutical co., Ltd. , https://www.anabolicsteriod.com
1. Ultra-low frequency can be carried out during handover, overhaul, partial replacement of windings and routine tests. The motor is subjected to a withstand voltage test with a 0.1 Hz ultra low frequency, and the defect of the end insulation of the generator is more effective than the power frequency withstand voltage test. The reason is that at the power frequency voltage, the capacitance current flowing from the wire rod causes a large voltage drop when flowing through the semiconductor antihalation layer outside the insulation, and the ultra low frequency thus causes the voltage of the end bar to be insulated. In the case of ultra-low frequency, the capacitance current is greatly reduced, and the voltage drop on the semiconductor antihalation layer is also greatly reduced, so the voltage on the end insulation is high, which is convenient for detecting defects.
2. Ultra-low frequency connection method: The test should be carried out in phase separation, the test phase is pressurized, and the non-test phase is short-circuited to ground.
3 Ultra-low frequency, according to the requirements of the relevant regulations, the test voltage peak can be determined by the following formula:
Umax= βKUo where Umax : is the peak value (kV) of the test voltage of 0.1 Hz
:: the equivalent coefficient of 0.1Hz and 50Hz voltage, according to the requirements of China's regulations, take 1.2
K: usually take 1.3 to 1.5, generally take 1.5
Uo : generator stator winding rated voltage (kV)
For example, for a generator with a rated voltage of 13.8 kV, the peak value of the test voltage for ultra-low frequency is: Umax=√2 ×1.2×1.5×13.8≈35.1(kV)
4. The ultra-low frequency test time is carried out according to relevant regulations.
5. Ultra-low frequency In the process of withstand voltage, if there is no abnormal sound, odor, smoke and unstable data, it can be considered that the insulation has withstood the test of the test. In order to better understand the insulation, the surface condition of the insulation should be monitored as completely as possible, especially for air-cooled units. Experience has pointed out that appearance monitoring can detect abnormal generator insulation, such as surface corona and discharge, which cannot be reflected by the instrument.
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