A breakover diode(BoD) is functionally equivalent to a suppressor diode; it is a surge arrester. A BoD diode has a fixed breakdown voltage of several hundred volts up to several kilovolts and a high pulse load, which can be several hundred amperes.
Once the breakdown voltage is reached, the internal resistance of the breakover diode approaches zero. The rate of change is over 1000 V per microsecond (V/µs). A breakover diode forms the overvoltage protection of the thyristor and the protection against too fast voltage changes. The thyristor is triggered by the avalanche current.
Breakover diodes are used in high voltage switches and in the overvoltage protection of thyristors and diodes, also in laser pulsers and pulse generators.