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Test methods for high voltage test transformers

time:2022/1/20   source:华天电力  reading:326 time

Test methods for AC and DC high voltage test transformers


1. In general measurement of AC and DC high-voltage test transformers, after connecting the wires, first hang the wires connecting the test objects, and after raising the test voltage to the test voltage, read the corona and stray current I′ during the no-load test, and then connect the When the sample rises to the test voltage, read the total current I1.


2. When it is necessary to precisely measure the leakage current of the tested product, a high-voltage shielded microammeter should be connected in series in the high-voltage circuit; the wire should be wound tightly for several turns and then connected to the shield of the high-voltage lead.


Hipot Test Set.png

3. When the ground terminals of the test objects such as zinc oxide arresters and magnetic blowing arresters can be separated, the method of connecting an ammeter in series at the bottom (ground potential side) of the test objects can also be used for measurement, but a shielded wire must also be used; To exclude the influence of leakage current on the surface of the test object, a soft bare copper wire can be wound several times around the ground potential end of the test object to connect with the shield.


4. After the test is completed, reduce the voltage and return the voltage regulating potentiometer to zero, then press the green button to cut off the high voltage and turn off the power switch.


5. For small capacitor test products such as zinc oxide arresters, it is generally discharged through the piezoresistor, and the time is very fast. For large-capacitance test products such as cables and motors, it is generally necessary to wait for the voltage of the test product to self-discharge to less than 20% of the test voltage, and then discharge through the discharge rod. After the test sample is fully discharged and the grounding wire is hung up, the removal of the high-voltage lead and the replacement of the wiring are allowed.


During use, it is found that the red light is off, the green light is on, and the DC high voltage drops, which is the relevant protection action. At this point the following steps should be followed:


1. Return the voltage regulating potentiometer to the zero position.


2. Turn off the power switch, the panel indicators are not on.


3 After one minute, the low-voltage capacitor in standby is fully discharged before turning on the power switch again. Carry out the no-load test again, and after finding out the situation, the boost test can be performed again.


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