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Preparation before use of high voltage generator

time:2020/10/30   source:华天电力  reading:235 time


Preparation before using DC high voltage generator


1. Before using the DC high-voltage generator, Yangzhou Sudian staff will explain the following preparations.


⑴ The integrity of the DC generator should be checked before use, the connecting cable should not be open or short-circuited, and the equipment should not be broken or damaged.


⑵ Place the chassis and pressure doubler in a suitable and safe place, and connect the power cord, cable and grounding wire respectively. The protective grounding wire, the working grounding wire and the grounding wire of the discharge rod should be separately connected to the ground wire of the test product (ie one-point grounding) and ensure a good grounding. It is strictly forbidden to use the grounding wires in series with each other, so as to avoid the rise of ground potential during breakdown and cause counterattack and damage the instrument.


(3) Check whether the power switch is in the off position, and check that the electric potentiometer should be in the zero position, and the overvoltage protection setting dial switch is set in an appropriate position, generally 1.10 to 1.20 times the test voltage value.


DC Hipot Tester.png


2. No-load boost to verify the setting value of over-voltage protection


⑴Please make sure that the power supply is single-phase AC 220V, 50Hz. Turn on the power switch, and the green light is on at this time, indicating that the power is on.


⑵ Press the red button, the red light is on, indicating that the high voltage is connected.


(3) Gently adjust the potentiometer in a clockwise direction, and the output will start to boost from zero. The voltmeter displays the voltage (KV) value on the load sample, and the ammeter displays the sum of the current flowing on the sample and all the leakage currents. The current is in microamps (uA). After rising to the required voltage, record the ammeter readings within the specified time, and check the control box and output cables for abnormal phenomena and noise.


⑷ Reduce the voltage and reset the electric potentiometer to zero, then press the green button to cut off the high voltage and turn off the power switch.


3. Leakage and DC withstand voltage test on the sample


⑴Before the load test, install the high-voltage shielded micro-ammeter on the high-voltage output end of the pressure doubler, and connect the matching special high-voltage 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 correct, whether the grounding wire connection is reliable, and check whether the high-voltage safety distance meets the requirements before starting the high-voltage test of the test product.


⑶ After checking that there is no abnormal condition in the instrument, turn on the single-phase AC 220V power switch. At this time, the green light is on, indicating that the power is on. The DC leakage and DC withstand voltage test of the sample can be started.


⑷Press 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 potentiometer in a clockwise direction, and the output terminal 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, a slow boost is required, otherwise it may cause voltage overshoot, and it is also necessary to monitor that the charging current of the ammeter does not exceed the large 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 reset the potentiometer 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 work close to the test product and disconnect the wire after discharge (please refer to the discharge rod instruction manual for details). Slowly adjust the voltage regulator to the required voltage (current) value for small capacitor samples such as zinc oxide arresters and magnetic blown arresters, and then read the voltage (current) value from the digital display. When the zinc oxide arrester needs to be measured at 75%VDC-1mA, the voltage value should be stopped when the current reaches 1000uA (the voltage and current values can be recorded at this time), and then press the yellow button, the voltage will drop to the original value 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 it is necessary to monitor that the charging current of the ammeter does not exceed the large 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. Do not turn off the power at this time. The voltmeter shows that there is a voltage value, which is the stored voltage. Wait until the voltage drops to Around 2000V, the discharge rod can be used for multiple discharges to ensure safety.


4. During use, if the red light is off, the green light is on, and the DC high voltage drops, it is the relevant protection action. At this time, follow the steps below:


⑴ Return the potentiometer to the zero position.


⑵Turn off the power switch, the panel indicators are off.


(3) One minute later, after the low-voltage capacitor in standby is fully discharged, the power switch is allowed to be turned on again. Re-carry out the no-load test, and after finding out the situation, the boost test can be repeated.


6. Note: When doing cable test, a current-limiting resistor must be installed. (When doing other tests, current limiting resistors cannot be used).


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