Working principle of the characteristic comprehensive tester:
The power input passes through an operation box equipped with overcurrent automatic tripping and a zero-position interlock device to prevent sudden voltage application. The voltage is adjusted via an autotransformer and then input to the primary winding of the test transformer. According to the principle of electromagnetic induction, the secondary (high-voltage) winding obtains a voltage amplitude equal to the turns ratio multiplied by the primary winding voltage - power frequency high voltage. This power frequency high voltage is rectified by a high-voltage silicon stack and filtered by a voltage-stabilizing capacitor to obtain DC high voltage, whose amplitude is twice the effective value of the power frequency high voltage.
Precautions:
1. When conducting high-voltage tests, at least 2 or more personnel must participate, with clear division of labor and mutual communication methods. A dedicated person should supervise the on-site safety and observe the test status of the sample;
2. The transformer and control box should have reliable grounding;
3. During the test, the voltage increase speed should not be too fast, and sudden full voltage application or power cut-off is absolutely not allowed;
4. During voltage increase or withstand voltage tests, if any of the following abnormal conditions are found, immediately reduce the voltage, cut off the power, stop the test, and investigate the cause before retesting. ① The voltmeter pointer swings significantly; ② A burning smell or smoke from insulation is detected; ③ Abnormal sounds from the tested sample.
5. During the test, if the sample short-circuits or breaks down, the overcurrent relay in the control box will operate. At this time, return the voltage regulator to zero, cut off the power, and only then can the sample be removed.
