Usage methods and precautions for overloading transformers
Usage methods:
1 .Before use, you must read the operating instructions of the transformer and the instructions of the matching control box (station) in detail. Connect the connecting wire according to the instructions, and the ground wire should be well grounded.
2. The power supply of the dry-type transformer control box (station) is AC 220V and 380V, which are output to the low-voltage side input end of the transformer through the voltage regulator. The output can be continuously adjusted to the rated voltage through variable ratio.
3. Consider the safety of the dry-type test transformer and the rigor of the high-voltage test to avoid damage to the equipment or test products. The complete set of equipment includes: high-voltage test transformer, transformer control box (station), voltage divider device, ball gap protector, discharge rod, high-pressure oil cup, high-voltage silicon stack (for DC test), digital microammeter (for DC test).
4. When doing a DC withstand voltage or leakage current test, you can first screw the high-voltage silicon stack and microammeter on the high-voltage output end of the high-voltage test transformer, and then gradually increase the voltage to perform DC testing. test.
5. When two test transformers are connected in series, the rated output voltages of the first and second transformers are equal, and the ratio of their capacities is 2:1. The second transformer must be placed on an insulated on the bracket to ensure insulation from the ground. When connecting in series, pay attention to the markings on the transformer (see the wiring diagram) and make sure the polarity is connected correctly to ensure the output of the predetermined voltage. Otherwise, the output voltage will be zero.
Note: If A and B are connected reversely. It will cause the high voltage output to be zero (T1+T2=0), just change A and B.
Notes:
1. When doing a withstand voltage test, there will be three sounds due to the electrical distance:
2 .”Crack crackle”: It is the sound of ionized air.
3. “zi,zi”: It is the sound of air flowing.
4. “Pop”: loud and crisp, accompanied by sparks, is the sound of insulation (or air) being broken down.
5. Generally, air discharge is divided into three stages. The first stage is ionization. When the electric field is at a large point, it will enter the streaming stage, and at a large point the air will be broken down. If it only makes a “crackling” sound like fried beans and can last for one minute without breakdown, it is in principle in compliance with the national standard. If there is a “zi zi” sound but it persists for one minute without breakdown, it actually complies with the national standard requirements. However, the risk of long-term operation of the transformer with leakage is greater. The main reason for the high pressure noise is that the air distance between the main air channel (high-voltage coil and low-voltage coil) is insufficient.
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