Please help analyze the circuit, the 1500V surge test fails

fireboct

Please help analyze the circuit, the 1500V surge test fails [Copy link]

Please see the attached picture, other functions are normal, but the 1500V surge test burns the switch tube (short circuit). Can you please analyze if there are any defects in the 2 varistors or other circuits? Thank you.

24不可说

I encountered a similar problem and was considering whether to add a buffer absorption capacitor to the IGBT.

qwqwqw2088

During the burn-in test, the tube is not necessarily a varistor. The rated voltage of the varistor in the half-voltage or full-voltage range is generally 470V. Maybe other places, the whole lamp should be considered. If the high voltage is too high, pay attention to the creepage distance, wiring and components. If the circuit is really not good, you can add a discharge tube

Arvinˇ

1. Add a small resistor (NTC is the best) after the fuse to suppress the surge current. 2. In terms of power-on surge protection, a more complicated method is as shown in the figure below. Add this circuit after the rectifier bridge. The resistor is NTC and the thyristor is below. 3. Creepage distance is also very important. Do not allow arcing during the test. This is my personal opinion and is for reference only.

Arvinˇ

Also, are you sure your circuit diagram is correct? Did you miss a transformer secondary coil?

luck_gfb

Add a small electrolytic capacitor after the rectifier bridge to absorb it. If it affects the PF value, you can connect a diode in series with the capacitor.

langtuodianzi