Insulation strength test is the key to testing the insulation performance of wires and cables, and is mainly divided into withstand voltage test and breakdown test.
1. Withstand voltage test
Apply a test voltage higher than the rated working voltage to the test sample and maintain it for a specified time (such as a few minutes) to check whether breakdown occurs. This is a routine factory test used to check the reliability of the product under operating voltage and to detect serious defects in the insulation or major workmanship problems.
2.Breakdown test
Continue to increase the voltage until the insulation of the test sample breaks down, thereby measuring the breakdown voltage or field strength. This test is used to assess the safety margin of the cable insulation withstand voltage and is an important basis for cable design.
3. Test voltage type
According to the actual operating conditions of the cable, the test voltage waveform can be divided into three types: power frequency AC, DC and impulse voltage to simulate different working voltages and overvoltage conditions.
4. Partial discharge measurement
For high-voltage extruded cables, partial discharge measurement is required before leaving the factory (usually using electrical measurement methods). Partial discharge accelerates insulation aging, and this test is critical to ensure the long-term reliability of extruded cables, especially in high-voltage grades.
5. Aging and stability test
Through thermal aging test or thermal stability test, the long-term stability of insulation materials under the action of thermal, electrical and other stresses is assessed. Such tests help evaluate a cable's service life and ability to maintain performance.
These tests together constitute a complete evaluation system for the insulation performance of wires and cables and are the basis for ensuring the safe operation of products.