In recent years, digital isolation chips have been increasingly trusted by engineers in industrial, medical, automotive and other fields. Digital isolation chips are gradually replacing traditional optocoupler devices because of their small size, high integration, low power consumption, and high communication speed. The digital isolation chip is the core device of the high-voltage safety involved in the system, so it needs to be strictly screened when leaving the factory.
The UL1577 safety standard clearly stipulates that when the product leaves the factory, it must be tested for 60s under the insulation withstand voltage condition or 1s under 1.2 times the insulation withstand voltage condition corresponding to the product specification. Only products that pass the high voltage test can leave the factory. Taking a product with an isolation strength of 3000Vrms as an example, it needs to withstand 60s at an AC voltage of 3000vrms and a frequency of 60Hz or 1s at an AC voltage of 3600Vrms and a frequency of 60Hz when it leaves the factory. After passing the high voltage test, it can be shipped out of the factory.
The detection method of the high voltage test specified in UL1577 is to detect the leakage current of the insulating layer. If the withstand voltage of the insulating layer of the digital isolation chip can withstand the test high voltage, then the leakage current of the detected insulating layer will be relatively small. This value is usually uA level. This is because the low-frequency AC high voltage is applied. As long as there is a certain parasitic capacitance on both sides of the isolation, there will be AC leakage.Current exists. However, if the withstand voltage of the insulating layer of the digital isolation chip cannot withstand the corresponding high voltage, then the insulating layer will produce uncontrollable leakage current due to the high voltage, which will eventually cause damage to the isolation band.
Usually, the insulating layer of digital isolation chips has high environmental cleanliness requirements when they are manufactured, and there can be no air bubbles or voids, so as to ensure good insulation effect and long insulation life. However, in the actual production process, it is difficult to ensure that all chips are 100% guaranteed that the insulating layer is free of air bubbles or voids, and the presence of these voids or air bubbles will cause the insulation performance to decrease, but these voids or air bubbles cannot be detected by the method of detecting high-voltage leakage current. When high voltage is applied to both ends of the insulating medium, because of the presence of these bubbles or voids, partial discharge (Qpd: Partial discharge) will occur. A slight partial discharge has less impact on the insulation of power equipment and the insulation strength decreases slowly; and a strong partial discharge will make the insulation strength very fast.drop. This is an important factor that damages the insulation of high-voltage power equipment. Partial discharge will be accompanied by electrical pulses, ultrasonic waves, electromagnetic radiation, light, chemical reactions, and cause local heat generation. It is a sign of aging of electrical components. The applied voltage detected by partial discharge is not the insulation withstand voltage value, but the operating voltage applied to the insulating layer, because only the operating voltage acts on the insulating layer for a long time, and may cause repeated charging and discharging of defective products, which eventually leads to premature failure of the insulating layer. Therefore, VDE0884-10 safety regulations stipulate that when the product is tested at the factory, in addition to the high-voltage leakage current test, partial discharge testing is also required. The test voltage of partial discharge detection is 1.875 times the peak operating voltage, the test time is 1s, and the target value of the test result is the size of the leakage charge.
For the above-mentioned isolation voltage test and local discharge test, we can use the one sold by our agent.HT9464MThe test host performs certification testing, and the maximum test voltage can reach the rms effective value of AC 10kV.
According to customer needs, our company can customize the configuration of the multi-channel test system of the tester + sorter for customers, and the multi-channel automated test of the Qpd partial discharge of the digital isolator can be automatically completed in the production line.，
The Ramp climbing test mode that comes with the system can help digital isolator developers determine the maximum isolation voltage and VDE standard test mode that the isolator can withstand.
- Creation date: May 9, 2024
- Revision date: May 9, 2024