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Power Electronics
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Q141

A push pull inverter provides a

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Q142

An inductor is connected in series with SCR to protect it from

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Q143

The SCR would be turned OFF by voltage reversal of applied anode-cathode ac supply frequency of

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Q144

An SCR triggered by a current pulse through its gate can be turned off by

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Q145

A step-down chopper, fed from a 120 volt DC source, operates a DC motor whose armature e.m.f. and armature resistance are 100 volt and 0.5 Ω respectively. With the magnitude control ratio 0.6, the quadrant of operation DC motor is

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Q146

Match List-I with List-II and select the correct answer using the options given below:

List-I (Semiconductor Device)	List-II (Application)
a. Triac	1. Used in HVDC system
b. IGBT	2. Used in pulse generation
c. SCR	3. Used in motor control circuits
d. UJT	4. Used in ac regulators

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Q147

Which device is used in relaxation oscillator?

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Q148

For a single phase half-wave controlled rectifier has 400sin314t as the input voltage and R as the load. For a firing angle of 60° for the SCR, the average output voltage is

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Q149

What will be the one cycle surge current of a SCR if it has half cycle surge current rating of 5000 A for 50 Hz supply?

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Q150

. . . . . . . . is the device which acts like an N-P-N and a P-N-P transistor connected base-tobase and emitter-to-collector.

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Q151

An SCR has a turn on time of 4 µs. The gate pulse should be of duration about

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Q152

Which of the following is false for a thyristor?
1. Thyristor is a majority-carrier device.
2. The forward-bias portion of thyristor's i-v characteristics has two stable operating regions.
3. The forward-bias portion of thyristor's i-v characteristics has one stable operating region.
4. The negative gate current turns off the thyristor.

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Q153

The above graph depicts
Power Electronics mcq question image

Power Electronics mcq question image

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Q154

Which of the following does not cause permanent damage of an SCR?

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Q155

Which of the following is control element in Silicon Controlled Resistor (SCR)?

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Q156

The effect of source inductance on the performance of a single-phase and three-phase full converter is to

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Q157

An SCR has three terminals viz . . . . . . . .

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Q158

Which statement is correct for a UJT?

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Q159

In the NMOS inverter

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Q160

The frequency of oscillation of an UJT relaxation oscillator is

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