How to determine if a thyristor is damaged

When the thyristor is damaged and needs to be inspected and analyzed for its cause, the core can be removed from the cooling jacket, the core box can be opened, and the chip can be removed to observe the traces after the damage to determine the cause. Below are several common phenomenon analyses.

1. Voltage breakdown. The thyristor is damaged due to its inability to withstand voltage, and there is a smooth small hole in its chip that sometimes requires a magnifying glass to be seen. The reason may be due to a decrease in the withstand voltage of the diode itself or high voltage breakdown caused by circuit disconnection.

2. Current damage. The characteristic trace of current damage is that the chip is burned into a pit and rough, located far away from the control electrode.

3. The current rise rate is damaged. Its trace is the same as the current damage, and its location is near or on the control electrode.

4. Edge damage. He occurred at the chamfer of the outer circle of the chip, with small smooth holes. With a magnifying glass, fine metal scratches can be seen on the chamfered surface. This is caused by the manufacturer's careless installation. It causes voltage breakdown.