The DC high voltage generator can be used to test the transformer's withstand voltage.
DC high voltage generator is specially designed to detect the electrical insulation strength and leakage current of power devices. By generating high-voltage DC, it carries out a DC withstand voltage test or DC leakage current test on high-voltage electrical equipment such as zinc oxide arresters, power cables, and transformers. During the operation, it is necessary to ensure that the instrument, discharge rod, pressure doubling cylinder, test connection wire, grounding wire, etc. are correctly connected, and the grounding wire is reliably connected, check whether the high voltage safety distance meets the requirements, and then the high voltage test of the test product can be started.
DC high-voltage generators need to follow a series of strict steps to ensure the accuracy and safety of the test when performing transformer withstand voltage tests. Here are the detailed steps:
Preparation work:
Check the equipment: confirm that the DC high voltage generator, pressure doubling cylinder, discharge rod, ground wire, and other equipment is intact, and the connection line is not open or short circuit phenomenon.
Install a high voltage shielding microammeter: Install a high voltage shielding microammeter on the high voltage output end of the pressure doubling cylinder, and connect the corresponding special high voltage wire to the microammeter and the tested product.
Check grounding: Ensure that all grounding cables are connected reliably, including the grounding of the control box, pressure doubling cylinder, and discharge rod.
Connection test: Connect the one-phase cable near the instrument end of the cable (three-phase cable for example) to the high-voltage output end at the top of the voltage-doubling cylinder, and short-ground the other two phases to ensure that the three-phase cable heads are suspended and the maximum distance between them.
Start testing:
Turn on the power: Turn on the single-phase 220V AC power switch. If the green light is on, the power supply is connected.
Start the high pressure: press the red button, the red light is on, and wait for the high voltage value to rise. Adjust the voltage potentiometer clockwise, the output value gradually rises from zero, and the speed is 3-5kV per second. For test items with large capacitors, the boost speed needs to be slower to prevent voltage overshoot.
Observe the ammeter: Closely observe the ammeter to ensure that the charging current does not exceed the maximum charging current of the DC high-voltage generator.
Complete the test:
Step-down treatment: After the test, the potentiometer will be zero, then press the green button, indicating that the high voltage has been cut off, turn off the power switch.
Discharge treatment: The discharge rod is used to discharge the test product several times, and the test product can be approached for subsequent disassembly after completion to ensure safety.