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Triple-frequency induced withstand voltage generatorThe induced withstand voltage should be applied at 80% of the factory value. The induced withstand voltage test is subject to the voltage standard and the rated withstand voltage of the neutral point terminal of the graded insulated transformer.
Note: For the highest voltage of the same equipment, two rated voltages are given for 220kV and above, considering the grid structure and voltage level, configuration and performance of overvoltage protection devices, equipment type and insulation characteristics, acceptable insulation failure rate, etc. Fully insulated transformers: For fully insulated transformers of 110kV and below, they are generally three-phase transformers. A three-phase symmetrical AC power supply is used, and a voltage of 2 times the rated voltage at a frequency more than 2 times is applied to the low-voltage winding or other winding terminals of the test object, with other windings open. Graded insulated transformers: In China, for power transformers of 110kV and above, graded insulation is usually adopted, that is, the insulation level of the neutral point is lower than that of the line end.
Let's first talk about the test method of the triple-frequency induced withstand voltage generator:
1. Test
Before conducting the frequency-multiplied induced withstand voltage test on the test object, a no-load test should be performed on this device first to check whether the device is intact.
(1) Wiring diagram for no-load test:
(2) Operation steps:
After confirming the wiring is correct, input three-phase voltage; turn on the power switch of the control box, and the green indicator light will be on (if not, please return the voltage regulator handle to zero); then press the start button, the red working light will be on, and you can start rotating the voltage regulator handle to increase the voltage, observing the voltmeter until it reaches full scale. If there is no abnormal situation during this process, it indicates that the device is normal. You should immediately return the voltage regulator handle to zero and disconnect the power supply. The no-load test is completed.
2. Test
(1) Connect the triple-frequency induced withstand voltage generator, control box, reactor (if needed) and the test object;
(2) Carefully check the connected lines, and after confirming that the wiring between the test object and this device is correct, input three-phase voltage. The operation steps are basically the same as those of the no-load test; when the voltage rises to the required value for the test object, stop increasing the voltage and maintain it for 40 seconds; if no abnormal situation occurs, it indicates that the test object has passed this test. At this time, you should immediately return the voltage regulator handle to zero and quickly disconnect the three-phase power supply. The test is completed.
Note: The above information and technical parameters are compiled and released by Yangzhou Dary Electric Co., Ltd.
