The AC withstand voltage test is the most effective and direct method for evaluating the insulation strength of power equipment. The following is a detailed introduction to the AC withstand voltage test:
1. Definition and Purpose
AC withstand voltage test refers to applying a certain frequency and amplitude of AC voltage to the tested equipment to test its insulation performance and withstand voltage capability under high voltage environment. This testing method can simulate the voltage fluctuations and overload situations that equipment may encounter during actual operation, thus comprehensively evaluating the electrical safety performance of the equipment. The main purpose is to evaluate the voltage resistance and insulation quality of electrical equipment, as well as to identify potential fault hazards.
2. Experimental principle and characteristics
① Test principle: By applying an AC voltage higher than the rated voltage of the equipment, observe the performance of the equipment under extreme voltage conditions, and evaluate its voltage resistance and stability.
② Characteristics:
The AC withstand voltage test voltage is generally higher than the operating voltage, so the equipment has a larger safety margin after passing the test.
This experiment can simulate the voltage environment of the equipment in actual operation more realistically, making it more suitable for evaluating the equipment's voltage resistance and insulation quality.
During the testing process, it may further develop the existing weak points in the insulation, resulting in a cumulative effect of internal deterioration of the insulation, thus belonging to destructive testing.
3. Evaluation of experimental results and precautions
① Result evaluation:
Observe whether the leakage current of the tested equipment exceeds the specified value during the experiment. If the leakage current is large, it may indicate that there is a defect or aging in the insulation of the equipment.
Pay attention to observing whether there is any discharge phenomenon in the tested equipment during the experiment. Discharge may be a sign of internal equipment malfunction or damage to insulation materials.
Check whether the waveform and frequency of the test voltage meet the requirements. Waveform distortion or frequency deviation may affect the accuracy of test results.
② Attention:
This test can only be conducted after all non-destructive tests of the tested equipment have been qualified.
The insulation surface of the tested equipment should be wiped clean, and for multi oil equipment, the oil should be allowed to stand still for a certain period of time.
The insulation resistance and absorption ratio should be compared before and after the experiment, and there should be no significant changes.
The effects of humidity, temperature, and surface dirt should be excluded.
Strictly adhere to safety operating procedures to ensure personal and equipment safety during the testing process.
4. Application and Significance
The AC withstand voltage test is widely used in the quality inspection and safety evaluation of electrical equipment such as transformers, switchgear, cables, etc. It is a key link to ensure the safe and stable operation of power equipment. Through this experiment, weak links in the equipment insulation system can be identified in a timely manner, providing a strong basis for equipment maintenance and replacement. At the same time, it can also verify the operational capability of equipment under extreme voltage conditions, providing strong guarantees for the safe and stable operation of the power system.
In summary, the AC withstand voltage test is an indispensable and important part of electrical equipment testing.
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