By hvhipot 
What is the principle of AC withstand voltage test? HV Hipot Electric Co., Ltd. specializes in producing AC withstand voltage testers with a wide range of product options. When looking for an AC voltage withstand tester, choose HV Hipot Electric Co., Ltd..
The security of electronic devices is the most important part among the various factors that determine their quality. The safety parameters include the following parameters: AC/DC high voltage, DC high insulation resistance (or insulation resistance), grounding resistance, leakage current, pulse high voltage, pulse high current, etc. Since the first publication of IEC65 “Safety Requirements for Household and Similar General Purpose Electronic and Related Equipment Powered by Grid Power” in 1952 and its five editions and seven revisions, two major systems of IEC safety standards and UL safety standards have been formed worldwide.
Voltage withstand test
Voltage withstand testing, also known as high voltage testing or dielectric strength testing, may be the most familiar and commonly used in product process safety testing. It is actually referenced in every security standard, which indicates its importance.
Voltage withstand test is a non-destructive test used to test the insulation capability of products under frequent transient high voltages. It applies high voltage to the tested equipment for a certain period of time to ensure that the insulation performance of the equipment is strong enough. Another reason for conducting this test is that it can also detect some defects in the first phase, such as insufficient creepage distance and inadequate electrical clearance during the manufacturing process.
Principle
The initial voltage tester was just a simple transformer and regulator, which converted the mains power into the required test voltage and applied it to the tested sample. However, due to the volatility of the mains power, people sometimes have to adjust the output voltage to a level 20% higher than the actual required value to prevent possible fluctuations in the input voltage. At the same time, many safety standards specifically require that the voltage tester used has a capacity of 500VA or more, in order to ensure that the voltage tester still has sufficient output voltage when the sample has a large leakage current. However, with the development of technology, this requirement has become outdated. The new voltage withstand testers all have sufficient series resonance voltage regulation and load regulation, only some old safety standards still have requirements in this regard. In fact, many new standards no longer include 500VA capacity as a requirement for voltage testers. From the perspective of the user, the 500VA capacity of the voltage tester is actually a threat to the operator.
Due to different testing standards, large-scale testing on assembly lines, and increasing awareness of electrical safety performance, it is required that the functionality of voltage withstand testing devices be correspondingly improved. The functionality of voltage regulator type voltage withstand testing instruments is limited, and new voltage withstand testing instruments using fully electronic programmable technology and power electronics technology are becoming popular. At present, there are mainly two types of voltage withstand testing instruments: one uses a microcontroller as the monitoring center and digital waveform synthesis technology+linear power amplifier as the testing series resonance; Another approach is to use a microcontroller as the monitoring center and a SPWM pulse generator+IGBT (Insulated Gate Bipolar Transistor) pulse kilometer amplifier as the testing series resonance.
The structure of this voltage tester is relatively complex, and its anti-interference ability and reliability depend on the design of the entire machine and the quality of electronic components. The output waveform distortion is small, the output frequency is variable, the output voltage adjustment range is wide, and the control accuracy is high. The output voltage is stable within the power range and is not affected by load changes. The output power of the test series resonance can generally reach 500W, The instrument can automatically protect against high-power output, and the output voltage is set in the absence of voltage output. It has good safety and is easy to detect potential insulation performance hazards such as arcing, creepage, and flashover of the test sample. The voltage output method can meet multiple standard requirements through software, such as segmented boosting, timed boosting, and constant speed boosting. It can perform breakdown analysis and has fast breakdown protection speed. The leakage current display resolution can reach Danaon level, making it very suitable for high standard electrical or component testing. During work, there is minimal interference to the power grid, and calibration can be carried out through buttons or communication interfaces, making it easy to connect with a computer for testing, statistics, and sorting. It can continuously test the test samples.
The voltage tester is mainly composed of an AC high-voltage power supply, a timing controller, a detection circuit, an indication circuit, and an alarm circuit. The basic working principle is to compare the leakage current generated by the test high voltage output of the voltage tester with the preset judgment current. If the detected leakage current is less than the preset value, the instrument passes the test. When the detected leakage current is greater than the judgment current, the test voltage is instantly cut off and an audible and visual alarm is issued to determine the voltage strength of the tested component.