The application of thyristors is becoming increasingly widespread, and the main reasons for thyristor damage are voltage breakdown and overcurrent burnout. In practice, most cases are caused by voltage breakdown, due to the following reasons:

1: When the motor stops or changes phase, a back electromotive force is generated, resulting in instantaneous high voltage.

2: Surge high voltage caused by voltage fluctuations in the power grid or lightning strikes.

3: Poor contact between the internal windings or terminals of the motor can cause discharge and result in voltage superposition.

Due to these factors being short-term and easily overlooked, the thyristor often breaks down (the more obvious the situation is with higher motor power). In view of the above reasons, we have developed the "thyristor protection board" TY-BH160-3 (suitable for soft start thyristor protection of 110-160KW motors)