During on-site cable acceptance tests, power-frequency withstand voltage equipment is often bulky and requires a high-capacity power supply, while DC withstand voltage raises concerns about cumulative damage to XLPE insulation. The SRV-60 very low frequency withstand voltage test device uses a 0.1Hz AC output, and its stress effect on insulation is equivalent to that of power frequency. At the same time, because the frequency is reduced, the capacitive current of the test object is greatly reduced, and the required power supply capacity is only about 1/500 of that of power-frequency equipment. The device's volume and weight are significantly reduced, making it suitable for on-site transportation and operation.
Compared with power-frequency withstand voltage devices, the SRV-60 does not require a high-capacity voltage regulator or test transformer, simplifies wiring, and has low requirements for on-site power supply. Compared with DC withstand voltage, the 0.1Hz AC output does not form cumulative space charges in XLPE cable insulation, avoiding the insulation damage caused thereby, and is a non-damaging withstand voltage test method. For acceptance and preventive tests of XLPE power cables at 35kV and below, this device can perform equivalent AC withstand voltage assessment; for detecting insulation defects at the ends of large generators, its effect is better than that of power-frequency withstand voltage; it is also suitable for acceptance, overhaul, and routine tests of high-voltage motors. For cables at 110kV and above, variable-frequency series resonance AC withstand voltage tests should be used, and this device is not applicable.
For cable acceptance tests, the test voltage is set at 3U₀ and maintained for 60 min. For example, 6/10kV cables correspond to 18kV, and 21/35kV cables correspond to 63kV. Preventive test parameters vary according to regulations. In the Yangzhou area, it is recommended to give priority to the "Preventive Test Regulations for Power Equipment of Jiangsu Electric Power Company." The device has built-in overvoltage protection. When the test voltage exceeds 1.1 times the set value, the output is automatically cut off and an alert is issued, preventing the test object from being damaged by abnormal voltage.
The output voltage waveform distortion rate is less than 5%, and the peak instability is ≤1%, meeting the requirements for waveform quality in on-site tests. The device's operation process is simplified, making it suitable for operation and maintenance personnel to complete wiring and voltage application in on-site environments such as substations and cable trenches, reducing dependence on power supply capacity and auxiliary equipment.
