Explaining the Main “Structure” of a Withstand Voltage Tester
Explaining the main “structure” of a withstand voltage tester
Withstand Voltage Tester applies a voltage higher than normal working voltage to the insulation of the device under test (DUT) and maintains it for a specified period. If the insulation is good enough, the applied voltage will only produce a small leakage current. If the leakage current of the DUT's insulation remains within the specified range during the specified time, it can be determined that the DUT can operate safely under normal operating conditions.
Withstand voltage testers, depending on the product, have AC withstand voltage testing and DC withstand voltage testing. Obviously, for AC withstand voltage testing, it is necessary to consider whether the frequency of the withstand voltage test matches the operating frequency of the DUT; generally, the output voltage range of AC withstand voltage testers includes 3KV, 5KV, 10KV, 20KV, or even higher, while DC withstand voltage testers have output voltages of 5KV, 6KV, or even above 12KV.
The test system of a withstand voltage tester has three major modules: a programmable power supply module, a signal acquisition and conditioning module, and a computer control system.
Explanation of the "structure" of a withstand voltage tester:
1. Voltage boosting part
It consists of a voltage regulating transformer, a step-up transformer, and a power on/off switch for the boosting part. The 220V voltage is applied to the voltage regulating transformer through the on/off switch, and the output of the voltage regulating transformer is connected to the step-up transformer. Users only need to adjust the voltage regulator to control the output voltage of the step-up transformer.
2. Control part
It consists of current sampling, timing circuit, and alarm circuit. When the control part receives a start signal, the instrument immediately turns on the power to the boosting part. When it receives a signal that the current in the tested circuit exceeds the set value and emits an audible and visual alarm, it immediately cuts off the power to the boosting circuit. When it receives a reset or time-out signal, it cuts off the power to the boosting circuit.
3. Display circuit
The display shows the output voltage value of the step-up transformer. It displays the current value from the current sampling part and the time value from the timing circuit, generally.
The above is the structural composition of traditional withstand voltage testers. With the rapid development of electronic technology, microcontrollers, and computer technology, programmable withstand voltage testers have also developed rapidly in recent years. The main difference between programmable withstand voltage testers and traditional ones is mainly in the voltage boosting part. The high-voltage boosting of a programmable withstand voltage tester is not adjusted by a voltage regulator through the mains, but is controlled by a microcontroller to generate a 50Hz or 60Hz sine wave signal, which is then amplified by a power amplification circuit to boost the voltage. The output voltage value is also controlled by the microcontroller. The principles of other parts are not much different from traditional withstand voltage testers.
