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DC high voltage generator use

time:2021/5/8   source:华天电力  reading:241 time

DC high voltage generator is a kind of test instrument in the electric power industry, and it has many names, such as direct high power generator, DC generator, high voltage generator, high frequency DC high voltage generator, AC and DC high voltage generator, intermediate frequency DC high voltage generator . It is widely used in the DC withstand voltage test and leakage current test of electrical equipment, and it is specially set to test the voltage U1mA under 1mA and the leakage current under 0.75U1mA of the zinc oxide arrester.

According to regulations, different cables require different test voltages and pressurizing times. Taking the cross-linked polyethylene cable as an example, the above 6KV cable requires a DC test voltage of 25KV and a duration of 5 minutes.

In general test, it is necessary to slowly increase the voltage from 40% of the full test voltage to the full voltage for 5 minutes. If it is a new cable line that is less than a year old, the power outage will only last for one month. It can be done at 50% of the specified test voltage and lasts for 1 min. If the power is cut for one year, it should be done in accordance with the general test requirements.

DC Hipot Tester.png

The specific test voltage and pressure time requirements for different cables, as well as specific test requirements, are described in detail in the power cable preventive test regulations.

In order to reduce the occurrence of instrument failures, some operating procedures must be followed when using the DC high-voltage generator. Let's take a look at it below.

1. Connect the grounding terminal on the control box panel and the grounding terminal of the high-voltage tower with a grounding wire and connect it firmly to the ground wire of the site or test room. To ensure the safety of you and the equipment, please check the ground wire repeatedly to ensure that all parts are well grounded.

Use the provided seven-core cable to connect the control box and the high-voltage tower. The two ends of the cable are the same fast aviation plugs. Pay attention to insert the side gap of the plug to the thick convex part of the socket and tighten it clockwise. (Either end of the cable can be connected to the control box or high-voltage tower) Connect the power cord, and the power supply is single-phase AC 220v, power frequency 50hz.

2. If voltage regulation protection within the rated output voltage range is not needed, turn the overvoltage protection setting knob clockwise to a larger value. At this time, when the output voltage exceeds the rated output voltage, it will automatically protect and cut off the high voltage. If it is required to perform voltage regulation protection within the rated output voltage range, please boost the no-load boost to the predetermined protection voltage according to the above steps, and then slowly turn the overvoltage protection setting knob counterclockwise to the required voltage. Perform over-voltage protection action, the "over-voltage" indicator light is on, keep the over-voltage protection setting knob at this position, return the boost knob to the zero position, and turn off the power. After connecting the test product, the high voltage will be automatically cut off when the boost voltage exceeds the predetermined voltage.

3. Turn on the power switch. At this time, the power switch light (green) and the panel meter are on. Then the high voltage indicator (green) is on. If the high voltage prompt buzzer is in the on position, it will beep to remind the operator that the high voltage is being applied. At this time, turn the high voltage output adjustment knob clockwise to increase the voltage, and the voltmeter will display as Load the kv value of the voltage on the sample, and the ammeter shows the sum of the current flowing on the sample and all the leakage currents, but does not include the current of the built-in high voltage divider. The current is measured in microamperes, ua.

If the power switch is turned on, the high-voltage indicator light (green) does not light up, and the “return to zero” light (red) is on in the fault display, it means that the high-voltage output adjustment button is not at the zero position. Please turn this button counterclockwise to “zero”. Turn the trimming voltage knob back to the zero position, and some "return to zero" lights will go out, and then adjust clockwise to increase the voltage.

4. When the load of the DC high voltage generator is a large capacitive load, in order to avoid triggering over-current protection due to excessive charging current, please slow down the boost speed appropriately. After the test is completed, turn the output voltage adjustment knob counterclockwise to the zero position. At this time, the voltmeter still displays the voltage value on the sample. Please wait until the sample is discharged through the high-voltage tower to below 20kv before using the ground rod to discharge. Safety.

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