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Operation steps of DC withstand voltage

time:2020/12/24   source:华天电力  reading:430 time

The DC high voltage generator is mainly used for the DC withstand voltage and leakage test of zinc oxide arresters, cables, motors and other equipment. For the safety of people and equipment, the operator should follow the steps below:

⑴ Before the load test, install the high-voltage shielded micro-ammeter on the high-voltage output end of the high-voltage doubler, and connect the matching special shielded wires to the micro-ammeter and the test product respectively.

⑵ Check whether the instrument, discharge rod, pressure doubler, test product connecting wire, and grounding wire are correctly connected, whether the grounding wire connection is reliable, and whether the high-voltage safety distance meets the requirements, and everything is normal before starting the test.

DC Hipot Tester.png

⑶ After checking that there is no abnormality in the instrument, turn on the single-phase AC 220V power switch, and the green light is on at this time, indicating that the power is on. Press the set button again to enter the test setting interface before starting the DC leakage and DC withstand voltage test of the sample.

⑷ Press the red button, the red light is on, indicating that the high voltage is connected and the voltage is to be increased.

⑸ Gently adjust the coarse and fine adjustment of the potentiometer in the clockwise direction, and the output will start to boost from zero. The boost speed is appropriate to increase the test voltage by 3-5kV per second. For large-capacitance test products, the voltage must be increased slowly, otherwise it may cause voltage overshoot. It is also necessary to monitor that the charging current of the ammeter does not exceed the maximum charging current of the DC generator. When it reaches the required voltage or current, record the readings of the ammeter and voltmeter at the specified time.

⑹ After the test is completed, reduce the voltage, and after coarse and fine adjustment of the potentiometer back to zero, then press the green button to cut off the high voltage and turn off the power switch.

⑺ After the test is completed, use the discharge rod to discharge the test product several times, and then approach the test product and remove the wires after discharge.

For small capacitor samples such as zinc oxide arresters, magnetic blown arresters, etc., first use a rough adjustment to increase to 90% of the required voltage (current), and then use a fine adjustment potentiometer to slowly increase the voltage to the required voltage (current) value. Then read the voltage (current) value from the digital display. If you need to measure the zinc oxide arrester at 75%VDC-1mA, you should first increase the current to 1mA and stop the voltage value (the voltage and current value can be recorded at this time), and then press the yellow button, the voltage will drop to the original 75%, and keep this status. At this time, the microammeter value and voltage value can be read. After the measurement is completed, the potentiometer returns to the zero position counterclockwise, press the green button, and press the red button when the pressure needs to be increased again.

For large capacitor samples, the boost should be slower, and the charging current of the ammeter needs to be monitored not to exceed the maximum charging current of the generator. The boost speed must be slowed down to avoid excessive charging current. After the test, return the voltage regulator potentiometer to the zero position counterclockwise, and then press the green button to cut off the high voltage. At this time, pay attention that the voltage on the voltmeter drops to about 15kV, and then the discharge rod can be used for multiple discharges to ensure safety.

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