A thyristor has its gate current zero. To start conduction the forward voltage m

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Question
A thyristor has its gate current zero. To start conduction the forward voltage must exceed
Options
A. about 0.5 V
B. forward breakover voltage
C. on state voltage
D. peak working off state forward voltage

Correct Answer

forward breakover voltage

Explanation

With zero gate current, conduction can be started only if forward voltage exceeds breakover voltage.

Power Electronics problems

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1. A single phase fully controlled bridge rectifier is fed by a source having inductance. The output voltage during overlap period is
Options
A. V_m
B. 0.5 V_m
C. zero
D. 0.5 V_m - voltage drop across inductance

2. In a 3 phase semiconverter, the firing frequency is
Options
A. equal to line frequency
B. 3 times the line frequency
C. 6 times the line frequency
D. 12 times the line frequency

3. In dielectric heating, the thyristor circuits consist of
Options
A. rectifier-chopper combination
B. controlled rectifier
C. ac regulator
D. rectifier-inverter combination

4. In a multiphase chopper, the different choppers operate in
Options
A. series and all simultaneously
B. parallel and one at a time
C. parallel and simultaneously
D. either (b) or (c)

5. In the below figure, the average value of load current is 15 A. The load is highly inductive. The peak value of thyristor current is
Options
A. 15 A
B. 152 A
C.
D. 30 A

6. In the below figure the rms voltage across each half of secondary is 200 V. The peak inverse voltage across each of thyristor is
Options
A. 200 V
B. 2(200) V
C. 2(400) V
D. 800 V

9. In an SCR, the anode current consists of
Options
A. only holes
B. only electrons
C. both electrons and holes
D. either electrons or holes

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