High voltage generators, also known as DC high voltage generators or DC high voltage testers, are specifically used to test the electrical insulation strength and leakage current of power devices.
Generally, high voltage generators are used for DC withstand voltage tests on high-voltage electrical equipment such as zinc oxide arresters, power cables, transformers, and generators. Different test objects require different measurement methods.
1. Microammeter
The microammeter must have a metal shield and should be connected to the test object using shielded wires. The shield lead of the high-voltage lead should be tightly connected to the shield of the instrument end. If the surface of the test object is contaminated, to eliminate the influence of surface leakage current, a bare soft metal wire can be tightly wound around the high-potential end of the test object for a few turns and then connected to the shield of the high-voltage lead (see figure below).
2. Zinc Oxide, Arrester
For test objects such as zinc oxide and magnetic blow arresters where the grounding end can be disconnected, a current meter can also be connected in series at the bottom (ground potential side) of the test object for measurement. To eliminate the influence of surface leakage current, a soft bare copper wire can be wound around the ground potential end of the test object for a few turns and connected to the shield of the shielded wire (see figure below).
For small-capacitance test objects such as zinc oxide arresters, the discharge time through the voltage-measuring resistor is usually very fast. For large-capacitance test objects such as cables, it is generally necessary to wait until the test object voltage self-discharges to below 20% of the test voltage before discharging with the matching discharge rod. After the test object is fully discharged and the grounding wire is connected, it is allowed to remove the high-voltage lead and change the wiring.
Finally, it must be emphasized that personnel using the DC high voltage tester must be professionals with a "High Voltage Test Work Certificate".
