The hipot tester is also called an electrical dielectric strength tester or a dielectric strength tester. A test of applying a specified AC or DC high voltage between the live part and the non-live part (usually the casing) of the electrical appliance to check the withstand voltage capability of the insulating material of the electrical appliance.
In the long-term operation of electrical equipment, not only must bear the role of the specified working voltage but also bear the action of overvoltage that is higher than the rated working voltage for a short time during the operation process (the overvoltage value may be several times higher than the rated working voltage value times). Under the action of these voltages, the internal structure of the electrically insulating material will change.
When the overvoltage intensity reaches a certain value, the insulation of the material will break down, the electrical appliance will not operate normally, and the operator may be electrocuted, endangering personal safety.
The structure of the hipot tester
It is composed of a voltage regulating transformer, a step-up transformer and a power-on and cut-off switch of the step-up part.
The 220V voltage is connected to the step-up transformer by connecting and cutting off the switch to the voltage-regulating transformer. The user can control the output voltage of the step-up transformer simply by adjusting the voltage regulator.
The control part consists of the current sampling, time circuit, and alarm circuit. When the control part receives the start signal, the instrument immediately turns on the power supply of the booster part. When the current of the circuit under test exceeds the set value and an audible and visual alarm is issued, the power supply of the booster circuit is cut off immediately. Cut off the boost circuit power supply when receiving reset or time-out signal.
The display shows the step-up transformer output voltage value. Displays the current value from the current sampling part, and the time value of the time circuit is generally a countdown.
This is the structure of the traditional hipot tester. With the rapid development of electronic technology and single-chip, computer technology; the program-controlled hipot tester has also developed rapidly in recent years. The difference between the program-controlled hipot tester and the traditional hipot tester is mainly the boosting part. The high-voltage boost of the program-controlled hipot tester is not adjusted by the voltage regulator through the mains, but is controlled by a single-chip computer to generate a 50Hz or 60Hz sine wave signal and then amplify and boost through the power amplifier circuit, and the output voltage value is also determined by the single-chip computer. It is controlled by a chip computer, and other parts of the principle are not much different from the traditional pressure tester.