What is the cause of the damage of silicon rectifier components?

In the self-excited synchronous motor, the reliability of silicon rectifier and affect the reliability of the motor. The damage of silicon rectifier element has some of the following reasons:

1 specifications are inappropriate, the actual forward current, reverse voltage exceeds the allowable value of the element.

2 operation, operation and maintenance of the process, the operation is not properly, generating a voltage, the original breakdown. For example, when the rotor insulation resistance is measured with a shake table, the rectifier element is not disconnected, nor does it use a wire to connect the silicon element to the silicon element. The non - same time, the main circuit of the electrical connection with the silicon element suffered lightning attacks and breakdown, etc..

3 the load power factor is too low, the excitation circuit is over a long period of time, the silicon rectifier element is caused by overheating and damage.

4 silicon element heat dissipation area is not enough or the ambient temperature is too high, causing the heat dissipation, and is burned, etc..