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Electronics and Communication Engineering - Power Electronics

Exercise : Power Electronics - Section 3
26.
To protect an SCR against high di/dt we connect
a capacitance in series with SCR
a capacitance in parallel with SCR
an inductance in parallel with SCR
an inductance in series with SCR
Answer: Option
Explanation:

current through inductance cannot change instantaneously.

27.
In a parallel inverter
the commutating capacitor C is across the primary of transformer and the load is across the secondary
the commutating capacitor and load are connected across the secondary of transformer
the commutating capacitor C and load are connected in series and the combination is across the secondary of transformer
none of the above
Answer: Option
Explanation:
No answer description is available. Let's discuss.
28.
A silicon controlled switch has :
2 leads
3 leads
4 leads
5 leads
Answer: Option
Explanation:

Anode, cathode, anode gate and cathode gate.

29.
A dc chopper V = 500 V feeds an electric fraction dc series motor. The chopping frequency is 400 Hz. The series inductance required to limit the maximum current swing to 10 A is
20 mH
about 31 mH
about 51 mH
about 92 mH
Answer: Option
Explanation:

.

30.
A single phase fully controlled bridge rectifier is fed by a source having inductance. The output voltage during overlap period is
Vm
0.5 Vm
zero
0.5 Vm - voltage drop across inductance
Answer: Option
Explanation:

During the period of overlap all the four thyristors conduct and load is effectively short-circuited. Output voltage is zero.

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