In the field of power equipment testing, the AC withstand voltage test is an important method for evaluating the insulation performance of electrical equipment. As a core component of the testing equipment, the series resonance device, with its unique performance advantages, plays an irreplaceable role in high-voltage tests. This article will systematically introduce how to conduct AC withstand voltage tests using the series resonance device, providing practical references for relevant technicians.
The working principle of the series resonant device is based on the resonant characteristics of inductors and capacitors. When the inductance of the reactor in the device and the capacitance of the test sample reach the resonant state at a specific frequency, a high-quality factor voltage amplification effect will occur in the circuit. This characteristic enables the test system to generate high voltages that meet the test requirements with relatively low input power. Compared with traditional test transformers, the series resonant device has significant advantages such as small size, light weight, and good output waveform.
Before conducting the AC withstand voltage test, thorough preparations must be made. Firstly, it is necessary to confirm the rated voltage of the tested equipment and the test standards, and determine the test voltage value according to relevant regulations. Secondly, the equivalent capacitance of the tested equipment should be calculated, which is a key parameter for selecting an appropriate resonant device. At the same time, the safety of the test environment should be checked to ensure there is sufficient space distance and reliable grounding measures. The test personnel should wear qualified protective equipment and set up clear warning signs in the test area.
During the test wiring process, the following points need to be particularly noted: Connect the high-voltage output terminal of the resonance device to the tested equipment, and ensure that the insulation strength and mechanical stability of the connection lines are maintained. The selection of the reactor should be matched according to the capacitance value of the tested equipment. Usually, a multi-section reactor connected in series is adopted to flexibly adjust the inductance. The installation position of the voltage divider should be as close as possible to the tested equipment to obtain accurate voltage measurement results. After all the wiring is completed, it must be checked and confirmed by a dedicated person.
The setting of test parameters is a crucial step in ensuring the quality of the test. The frequency selection should take into account the working range of the device and the characteristics of the tested equipment. Usually, it is within the range of 30-300Hz. The test voltage should be set according to the standard requirements, generally being 1.5-2 times the rated voltage of the equipment. The rising speed should be controlled at 1-2 kV/s to avoid voltage fluctuations causing impacts on the equipment. The test duration is usually 1 minute, and in special cases, it can be extended to 5 minutes.
The operation process of the test needs to strictly follow safety regulations. Firstly, a no-load test is conducted to confirm that the device is working properly and the output voltage meets the expected value. Then, the tested equipment is connected, and the voltage is slowly increased to the test value. During this process, the voltage and current waveforms should be closely monitored. If any abnormal discharge, local overheating or waveform distortion is found during the test, the voltage should be immediately reduced and the cause should be identified. After the test is completed, the power supply should be cut off first, and then a special discharge rod should be used to fully discharge the tested equipment.
Data recording and analysis are crucial steps in the experiment. Key parameters such as test voltage, current, frequency, and duration should be meticulously recorded, along with any abnormal phenomena during the test. By analyzing the voltage-current characteristic curve, the insulation condition of the equipment can be evaluated. The test report should include information about the equipment, test conditions, test results, and conclusion suggestions, providing a complete basis for the assessment of the equipment’s status.
The maintenance and upkeep of the series resonant device directly affect its service life and test accuracy. After each test, the device surface should be cleaned and the connection of each component checked for looseness. Regularly calibrate the voltage divider and measurement system to ensure that the measurement accuracy meets the requirements. For devices that are not used for a long time, they should be stored in a dry and ventilated environment and regularly powered on for inspection. When a fault is detected, it should be repaired by professionals and the core components should not be disassembled by oneself.
In practical applications, the selection of series resonant devices needs to take into account various factors. For equipment tests in substations, large devices with an output voltage of up to 500 kV are usually chosen; while for cable line tests, more emphasis is placed on the portability and frequency adjustment range of the device. Modern intelligent resonant devices integrate functions such as automatic tuning, remote control, and data storage, significantly improving the testing efficiency and safety.
Safety precautions must always be kept in mind. The test area should be equipped with double protection, and non-test personnel are not allowed to enter. Operators should stand on insulating mats to avoid direct contact with the electrified parts. During the test, it is strictly prohibited to change the wiring or adjust the parameters. In case of severe weather such as thunderstorms, the test should be suspended. A complete emergency plan is also indispensable, including measures for electric shock first aid and fire handling.
As power equipment continues to evolve towards higher voltages and larger capacities, the technology of series resonance devices is also constantly innovating. New technologies such as digital control of variable frequency power supplies, modular design of reactors, and the application of intelligent diagnostic systems are driving the development of AC withstand voltage tests towards greater efficiency and accuracy. In the future, combined with the remote monitoring and data analysis capabilities of the Internet of Things, the intelligence level of the tests will be further enhanced.
Through scientific and standardized AC withstand voltage tests, insulation defects of equipment can be effectively detected, preventing the occurrence of operational accidents. As the test executors, we not only need to master the operation skills of the series resonance device proficiently, but also should establish a strong safety awareness to ensure that each test can be completed safely and accurately, thus safeguarding the reliable operation of the power system.
Post time: Dec-15-2025