dv/dt protection is provided to the SCR by –

dv/dt Protection

A non-uniform distribution of current in the junction occurs when the anode current rise rate (di/dt) is large. This further results in the formation of regional hot spots close to the gate-cathode junction because of the high current density. Because of the warming effect, the SCR can be harmed. As a result, the di/dt has to be maintained below the predetermined limits when the SCR is turned on. A thyristor and an inductor are connected in series to reduce the fast rate of current change.

Junctions J and J are forward biassed and junction J is reverse biassed when the SCR is forward biassed. The reverse-biased junction J displays capacitor-like properties. The pace at which a forward voltage is supplied across the SCR determines how much charging current flows through junction J. Even in the absence of a gate signal, this current is sufficient to activate the SCR. This is referred to as dv/dt SCR triggering. Utilizing the RC snubber network across the SCR can lessen this.

Summary:

dv/dt protection is provided to the SCR by – (a) Connecting a capacitor & resistor in parallel with the device (b) Connecting a capacitor in parallel with the load (c) Connecting an inductor in series with the load (d) Connecting an inductor & resister in parallel with the device

The SCR is protected from dv/dt by having a capacitor and resistor connected in parallel to it. Silicon Controlled Rectifier (SCR) is a unidirectional semiconductor device that is made of silicon. It is the solid-state equivalent of thyratron and is therefore called a thyristor or thyroid transistor.