Several measurement methods for DC High Voltage Tester

a. In general, when the line is connected, hang the connecting test sample line, raise it to the test voltage, read corona and stray current I during the air test, and then connect the test sample to the test voltage to read the total current I1; leakage current of test object: IO =I1-I’

b. When accurate measurement of leakage current of the tested object is required, the high voltage micro safety meter shall be connected at the high-voltage side (see the figure below)

Wiring diagram of connecting micro ammeter to CX high voltage side of test sample

The micro safety meter must be metal shielded and shall be connected with the test piece by shielding wire. The shielding lead out of high voltage lead shall be closely connected with the shielding at the instrument end. If the surface of the test sample is polluted, the leakage current on the surface of the test piece should be eliminated. It can be connected with the shielding of the high voltage lead after several laps of bare metal soft wire at the high potential end of the test sample (see the figure below).

c. When the grounding ends of zinc oxide and magnetic blow arrester can be disconnected, the current meter can be connected in series at the bottom (ground potential side) of the test sample. When the influence of leakage current on the surface of the test piece is to be eliminated, soft bare copper wire can be used to wrap several circles around the ground potential end of the test sample and connect with the shielding wire (see the figure below)

13. For small capacitance test products such as zinc oxide arrester, the discharge time is very fast through measuring resistance. For large capacitance test products such as cables, the voltage of the test object should be discharged from the voltage to less than 20% of the test voltage, and then discharged by the supporting discharge rod. Only after the test sample is fully discharged, the grounding wire is hung, so that the high voltage lead can be removed and replaced.

14. Operation after protection action

It is found that the green light is off, the red light is on and the voltage drops during the use, which means the relevant protection action. At this time, the power switch shall be turned off, and the panel indicator light shall not be on. Return the voltage regulator to zero position, and it is allowed to turn on the power switch again after the low voltage capacitor is fully discharged in standby mode one minute later. The no-load test can be conducted again and the pressure-up test can be conducted again after finding out the condition.