The basic principle of the withstand voltage tester

A voltage higher than normal operation is applied to the insulator of the device under test for a specified period of time. If the insulation between them is good enough, the voltage applied will only produce a small leakage current. If the leakage current of the insulator of a device under test is kept within the specified range within the specified time, it can be determined that the device under test can operate safely under normal operating conditions.
In the test, when the sample reaches the specified time under the required test voltage, the withstand voltage tester automatically or passively cuts off the test voltage; once a breakdown occurs, the current exceeds the set breakdown (protection) current, and the output can be automatically cut off and an alarm is issued at the same time to determine whether the sample can withstand the specified insulation strength test. It can intuitively, accurately, quickly and reliably test the electrical safety performance indicators such as the withstand voltage, breakdown voltage, leakage current, etc. of various objects under test, and can perform different forms of dielectric performance tests such as power frequency and DC, as well as surge, power dynamometer shock wave, etc. under the test conditions specified by IEC or national safety standards.
The transition of China's withstand voltage tester to mass production and the formation of a new category of safety test instruments began in the early 1980s. Against the background of the comprehensive formulation and mandatory implementation of various national safety standards, manufacturers quickly launched a large number of new products of different models. At present, the technical indicators of safety withstand voltage test instruments in China are basically equivalent to those in foreign countries.
At home and abroad, such instruments also have different names such as withstand voltage tester, dielectric breakdown device, withstand voltage tester, surge insulation tester, high voltage tester, etc.
The main test indicators of electrical safety include AC/DC withstand voltage strength test, insulation resistance test, leakage current test, ground resistance test, etc. The withstand voltage tester is an instrument for measuring the withstand voltage capacity of various electrical devices, insulation materials and insulation structures. The instrument can adjust the output required AC (or DC) test voltage and set the breakdown (protection) current. I believe that through this article you have a deeper understanding of withstand voltage strength testing.
Structure of withstand voltage tester
(1) Step-up part
It consists of a voltage regulating transformer, a step-up transformer and a power on/off switch of the step-up part. The 220V voltage is added to the voltage regulating transformer by the on/off switch. The output of the voltage regulating transformer is connected to the step-up transformer. The user only needs to adjust the voltage regulator to control the output voltage of the step-up transformer.
(2) Control part It
consists of current sampling, time circuit and alarm circuit. When the control part receives the start signal, the instrument immediately connects the boost part power supply. When the current of the measured circuit exceeds the set value and the sound and light alarm is issued, the boost circuit power supply is immediately cut off. When the reset or time-out signal is received, the boost circuit power supply is cut off.
(3) Display circuit
The display shows the output voltage value of the boost transformer. The current value of the current sampling part and the time value of the time circuit are generally countdown.
(4) Programmable withstand voltage tester
The above is the structure of the traditional withstand voltage tester. With the rapid development of electronic technology and single-chip and computer technology; programmable withstand voltage testers have also developed rapidly in recent years. The difference between programmable withstand voltage testers and traditional withstand voltage testers is mainly the boost part. The high voltage boost of the programmable withstand voltage tester is not regulated by the voltage regulator through the mains, but is controlled by a single-chip computer to generate a 50Hz or 60Hz sinusoidal wave signal and then amplified and boosted by the power amplifier circuit. The output voltage value is also controlled by the single-chip computer. The principles of other parts are not much different from those of traditional withstand voltage testers.
Development of withstand voltage tester in China
The 1960s was the initial period of withstand voltage tester in China. Due to the limitations of technology, process, components and other factors, the product varieties were few, the precision was low, and the inherent safety performance was poor. It started from the simple tester that manufacturers armed themselves to conduct withstand voltage tests on products or parts. After further improvement, a few varieties became commodities. The representative product is JC-4 dielectric breakdown device, but the development and production of withstand voltage tester has been stagnant in the 1970s. In 1970, JC-4 became the only withstand voltage tester model on the market.