In a thyristor di/dt protection is achieved through the use of
In a thyristor di/dt protection is achieved through the use of
Right Answer is:
L in series with the thyristor
SOLUTION
Overcurrents may damage the semiconductor devices, due to the junction temperature exceeding the rated value. Thus, there is a need for the overcurrent protection of semiconductor devices. Overcurrent Protection is also called di/dt protection.
- When a forward voltage is applied to a thyristor, and it is turned ON by means of gate current, conduction of anode current across the junction commences in the immediate neighborhood of the gate connection and spreads from there across the whole area of the junction.
- Modern thyristors are so designed that the conduction area spreads as rapidly as possible. Nevertheless, if the rate of rising of anode current di/dt is very high, then, a local hot spot will be formed in the neighborhood of the gate, due to the high current density in that part of the junction that has commenced to conduct.
- This localized heating may permanently damage the device.
- To limit di/dt to safe limits, a small inductance L is connected in series with the device as it prevents the high rate of change of current through it.