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DC high voltage generator cable withstand voltage

time:2020/8/29   source:华天电力  reading:710 time

According to the latest national standards and regulations, AC should be used for the withstand voltage of some electrical equipment such as cables, referred to as AC withstand voltage. However, due to equipment and regional differences, some parts use DC to complete the withstand voltage of electrical equipment such as cables. Pressure test. The simplest and most portable instrument that can complete the DC withstand voltage should be the ZGF DC high voltage generator. Below we will briefly explain how the DC high voltage generator completes the cable withstand voltage.

The withstand voltage of the DC high voltage generator is basically the same as the AC withstand voltage, but the output voltage is changed from AC to DC, so the cable handling is also consistent. Connect the one-phase cable near the instrument end of the cable (a three-phase cable as an example) to the high-voltage output on the top of the DC high-voltage generator voltage doubler (the connecting wire is left floating), and the other two phases are short-circuited to ground (if armored shielding is also required) Grounding), the opposite end of the cable shall ensure that the three-phase cable heads are in the state of suspension and maximum distance.

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Connect the control box of the DC high voltage generator and the pressure doubler as required. The intermediate frequency output is connected to the intermediate frequency input of the pressure doubler. The grounding of the DC high voltage generator control box and the pressure doubler must be grounded. A current-limiting resistor (standard configuration of the instrument) is connected in series between the high-voltage output on the top of the voltage doubler and the high-voltage connection of the cable, that is, the current-limiting resistor is twisted into the top of the voltage doubler and then connected to the high-voltage output line between the cable. If you need to check the leakage current, connect the microammeter to the upper end of the current-limiting resistor and then connect the high-voltage output.

Power on the control box, turn the boost knob of the control box counterclockwise to the zero position and the light is on, and press the start button. Rotate the boost knob of the control box clockwise and adjust it until the instrument high-voltage meter shows the test voltage required for the test. Maintain the withstand voltage for a certain period of time. After the test is completed, turn the boost knob counterclockwise to reduce the pressure to zero, press the stop button and cut off the power. Then use the discharge rod for safe discharge, and the disconnection operation can only be carried out after the complete discharge. Follow this step to complete the withstand voltage test of the other phases of the cable.

Special considerations: When making the cable withstand voltage, it is best to connect a current-limiting resistor to prevent the large current generated by the cable breakdown from damaging the instrument; it is necessary to discharge the cable before wiring the cable and before removing the wire after the test is completed. , To avoid personnel safety accidents.

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