Cable withstand voltage test is a kind of AC voltage test, also known as power frequency withstand voltage test.
1. Test supplies
The length of the terminal part of the test object and the method of making the terminal head must ensure that there will be no discharge along the surface or internal breakdown under the specified voltage of the cable voltage withstand test. If the test needs to be carried out in the water tank, the length of the two ends of the test object protruding from the water surface shall not be less than 200 mm, and the discharge along the surface shall not occur under the specified test voltage.
2. Steps of withstand voltage test
The test steps must meet the requirements of the operation procedures of the withstand voltage test. When carrying out the withstand voltage test, the difference between the withstand voltage test temperature and the ambient temperature shall not exceed 3 ℃. The voltage should start from a lower value, rise slowly and relatively smoothly to the specified test voltage value, and maintain the specified withstand voltage time. When the voltage is reduced, the power supply can be cut off until it is reduced to 40% of the specified voltage value of the cable withstand voltage test. In this experiment, it is absolutely not allowed to cut off the power supply suddenly under the condition of high voltage, so as to avoid overvoltage.
3. Evaluation of voltage test
If the test cable is continuously tested within the specified time and no breakdown occurs, it can be considered that the test object has passed the power frequency withstand voltage test. However, if during the test, the end or terminal of the cable is discharged along its surface or is internally broken down, it is also allowed to make another end connection and repeat the test. Unless there is a special regulation in the product standard, all cable voltage withstand tests need to be timed again. During the test process, if the withstand voltage test is stopped due to power failure, the test must be repeated unless there are special provisions in the product standard.
