Xinjiang 35kV Cable AC Withstand Voltage Test Report

PART 1: Main Information of On-site Test

On-site Test Instrument Picture

PART 2: Test Process

There are several newly laid 35kV cables with a length of about 400m on site, which require handover tests before being put into operation. This AC withstand voltage test uses series resonance equipment. The test method refers to the handover test standards, and the test purpose is to evaluate the main insulation strength of the cable, eliminate hidden dangers and defects, and ensure smooth commissioning.

According to the cable's specification, model, and length parameters, this test uses two or three reactors connected in series.

Place the variable frequency power supply, excitation transformer, reactor, and voltage divider in appropriate positions and connect the power cables, testing cables, and ground wires respectively. The protective ground wire, working ground wire, and the ground wire of the discharge rod should be separately connected to the ground wire of the test object (i.e., single-point grounding).

1. Connect correctly, and power can only be supplied after checking that there are no errors.

2. Set system parameters: voltage divider ratio, excitation transformer ratio, reactor inductance, date, and time.

3. Set test parameters: four setting items including test voltage, withstand time, frequency range, and excitation intensity.

4. Under the start withstand voltage test menu, there are manual test mode, automatic frequency search mode, and automatic test mode.

According to the requirements of the GB50150-2016 Standard for Hand-over Test of Electrical Equipment in Electrical Installation Engineering, the test voltage for U0/U: 26/35kV cables is 52kV, and the withstand time is 60min. All 35kV cables passed the AC withstand voltage test.

PART 6: Test Summary

During the operation of electrical equipment, the insulation will gradually deteriorate under the long-term effects of the electric field, temperature, and mechanical vibration, including overall deterioration and partial deterioration, which forms defects. In addition, because the AC withstand voltage test voltage is generally higher than the operating voltage, the equipment has a larger safety margin after passing the test. Therefore, the AC withstand voltage test is an important means to ensure the safe operation of electrical equipment.