The variable frequency resonant withstand voltage test device is widely used in industries such as power, railway electrification, steel, machinery, metallurgy, petroleum, and chemical engineering. It is suitable for AC withstand voltage tests of capacitive test samples with high voltage and large capacity.
The variable frequency resonance withstand voltage test device developed by Wuhan Guodian Xigao has been widely applied in AC withstand voltage tests for 10kV, 35kV, 110kV, 220kV, and 500kV polyethylene power cables. It is also suitable for AC withstand voltage tests of 60kV, 220kV, and 500kV GIS. It is also applicable for withstand voltage tests of large transformers, generators, etc.
Common Faults and Solutions in the On-site Testing of Frequency-Variable Resonant Withstand Voltage Test Equipment
1. The frequency conversion source main unit fails to find the resonance point.
Reason:
1) The system resonance point is outside the output frequency range of the host.
2) System wiring error;
3) The system is not reliably grounded;
4) The feedback signal from the high-pressure sampling is open-circuited or the connection is unreliable;
5) The test sample is faulty.
Exclusion method:
1) Check that the grounding device is reliable and verify if there are any disconnected points in the grounding connection lines.
2) Check the on-off status of the high and low voltage coils of the excitation transformer;
3) Check the on/off status of each reactor.
4) Check the continuity of the signal lines of the voltage divider;
5) Check the continuity of the high and low voltage capacitors of the voltage divider.
6) When the device is boosting power on its own, there is no resonance point. Therefore, it is necessary to check the connection status of the compensation capacitor.
2. Host reset
Reasons: Fluctuations in the power supply for the main unit; Strong external magnetic field interference; The main unit is not properly grounded.
3. The Q value of the device is too low, meaning that the voltage cannot be increased or cannot be increased to a sufficient level.
Phenomenon:
1) The tuning curve is a curve with a relatively low peak.
2) During the test, the voltage was relatively high, but the high voltage was low. Even before reaching the test voltage, the primary voltage had already reached the rated voltage, and the circuit automatically reduced the voltage.
Reason:
1) The reactance of the reactor does not match the capacitance of the test sample, and the resonance point has not been accurately determined.
2) The sample has a high loss rate and the system Q value is too low;
3) The high-voltage output voltage of the excitation transformer is relatively low;
4) The high-voltage connection line is too long or no high-voltage shielding wire is used.
Exclusion method:
1) Connect the compensation capacitor in parallel to the test circuit to increase the capacitance of the circuit;
2) Try to connect as many reactors in series as possible to increase the inductance of the circuit;
3) Increase the output voltage of the excitation transformer;
4) Dry the test specimen to enhance its insulation strength and reduce the active power loss of the circuit;
5) Generally, when the equipment requires a higher voltage output, a high-voltage grounding wire should be used, or the ordinary high-voltage output cable should be replaced with a shorter one, with the length generally not exceeding 5 meters.
4. During the variable frequency resonance withstand voltage test, the power supply tripped. The reasons were: excessive current at the moment of closing; short circuit in the resonance system circuit.
Exclusion method:
1) Replace the air switch with a higher current rating (or temporarily deactivate the leakage protection)
2) Check whether the resonant system circuit is short-circuited.
Post time: Jun-09-2026