Why can't the voltage withstand test be repeated?

source：未知　time：2024-09-09 10:09　

The withstand voltage test is a test of the insulation performance of the motor during the production and processing of the motor winding and the test of the whole machine product. The standard for qualification is whether the motor is not broken down under the specified conditions.

In order to ensure that the insulation performance of the motor meets the requirements, in addition to selecting suitable electromagnetic wires and insulating materials, reliable process guarantees must be provided, such as process protection, suitable tooling, good varnishing equipment, and suitable process parameters.

Taking high-voltage motor windings as an example, most motor manufacturers will conduct inter-turn and withstand voltage tests on each coil, and conduct withstand voltage tests on the winding core before varnishing and on the entire machine during inspection tests. This brings us back to the customer's doubts about the withstand voltage issue.

Objectively speaking, the withstand voltage test is an irreversible destructive test. Whether it is for windings or single coils, it is not recommended to conduct repeated tests based on the necessity of finding problems. When repeating the test under special circumstances, the test voltage should be reduced in accordance with the requirements of relevant standards to minimize the damage to the insulation.

About the withstand voltage tester The withstand voltage tester is an instrument for measuring the withstand voltage strength. It can intuitively, accurately, quickly and reliably test the withstand voltage, breakdown voltage, leakage current and other electrical safety performance indicators of various objects under test. The withstand voltage tester can be used to find problems and determine the purpose of insulation performance compliance.

● Detect the ability of insulation to withstand working voltage or overvoltage. ● Check the insulation manufacturing or maintenance quality of electrical equipment. ● Eliminate damage to insulation caused by raw materials, processing or transportation, and reduce the early failure rate of products. ● Check the electrical clearance and creepage distance compliance of insulation. Principles for selecting withstand voltage test voltage

The best way to determine the test voltage is to set it according to the specifications required for the test. In general, 2 times the rated voltage plus 1000V is used as the test voltage setting. For example, if the rated voltage of a product is 380V, the test voltage is 2 x 380 + 1000 = 1760 V. Of course, the test voltage will also be set differently depending on the level of the insulation layer, and different product types have different voltage requirements.

Why should we check the integrity of the test circuit frequently?

The withstand voltage tester on the production line is used very frequently, especially the test line and test fixture are often in an active state, which can easily cause the internal core wire to break and open the circuit, and it is generally not easy to find. As long as there is an open circuit at any point in the loop, the high voltage output by the withstand voltage tester cannot be really added to the object under test. These reasons will cause the set high voltage to not be really added to the object under test during the withstand voltage strength test. Naturally, the current flowing through the object under test is almost zero at this time. Since it does not exceed the set value of the upper limit of the withstand voltage tester, the instrument will give a prompt that the test is qualified, and it is considered that the insulation is qualified. But the test data in this case is not true. If the object under test happens to have defects in insulation performance at this time, it will cause serious misjudgment.

low voltage electric motor, Ex motor, Motor manufacturers in China, three phase induction motor, Wolong Nanyang Explosion Protection

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