Q5. Power Electronics Commutation Triggering and Protection

A type of triggering wherein a positive gate voltage between gate and cathode. It is simple, reliable, efficient and also easy to implement for most applications.

This form of SCR triggering or firing occurs when the voltage between the anode and cathode causes

avalanche conduction to take place.

A type of triggering wherein no application of gate current is required but once the rate of rise of anode to cathode voltage exceeds certain limits for the particular device SCR will start to trigger.

A type of triggering in which the increase in temperature further increases the temperature which will in turn increase the leakage current and will then turn ON the SCR.

A type of triggering in which electrical connection is not required from the firing mechanism but an isolated light source can be used.

The term ________________ means the transfer of currents from one path to another.

SCR turn off method that the source of commutation voltage is the supply source itself.

SCR turn off method in which forward current must be forced to zero with an external circuit

This is also known as self commutation, or resonant commutation, or load commutation. In this commutation, the source of commutation voltage is in the load. This load must be an under damped R-L-C supplied with a DC supply so that natural zero is obtained.

This is also a self commutation circuit in which commutation of SCR is achieved automatically by L and C components, once the SCR is turned ON. In this, the LC resonant circuit is connected across the SCR but not in series with load as in case of class A commutation and hence the L and C components do not carry the load current.