Thyristor Firing Circuits Objective Questions – Part 1

The gate-cathode curve for an SCR is given by the relation Vg = (1+10)Ig. The gate voltage source is a rectangular pulse of peak value 15 V and current = 0.659 A. Find the source resistance.

In the complete firing circuit, the driver circuit consists of

The duty cycle can be written as

In a single pulse semi-converter using two SCRs, the triggering circuit must produce

Find the amplitude of the gate current pulse, when the gate-cathode curve is given by the relation Vg = [(1+10) x Ig] The peak gate drive power is 5 Watts.

In a 3-phase full converter using six SCRs, gating circuit must provide

The magnitude of gate voltage and gate current for triggering an SCR is

Find the average gate power dissipation (P_gav) when the maximum allowable gate power dissipation (P_gm) = 10 kW, with a duty cycle = 50 %.

Find the triggering frequency when the average gate power dissipation = 0.3 W and the peak gate drive power is 5 Watts. The gate source has a pulse width of 20 μsec duration.

The major function of the pulse transformer is to