Test: Power Electronics - 3

# Test: Power Electronics - 3

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## 25 Questions MCQ Test Power Electronics | Test: Power Electronics - 3

Test: Power Electronics - 3 for Electrical Engineering (EE) 2023 is part of Power Electronics preparation. The Test: Power Electronics - 3 questions and answers have been prepared according to the Electrical Engineering (EE) exam syllabus.The Test: Power Electronics - 3 MCQs are made for Electrical Engineering (EE) 2023 Exam. Find important definitions, questions, notes, meanings, examples, exercises, MCQs and online tests for Test: Power Electronics - 3 below.
Solutions of Test: Power Electronics - 3 questions in English are available as part of our Power Electronics for Electrical Engineering (EE) & Test: Power Electronics - 3 solutions in Hindi for Power Electronics course. Download more important topics, notes, lectures and mock test series for Electrical Engineering (EE) Exam by signing up for free. Attempt Test: Power Electronics - 3 | 25 questions in 25 minutes | Mock test for Electrical Engineering (EE) preparation | Free important questions MCQ to study Power Electronics for Electrical Engineering (EE) Exam | Download free PDF with solutions
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Test: Power Electronics - 3 - Question 1

### In a dual converter both converters work as rectifiers.

Detailed Solution for Test: Power Electronics - 3 - Question 1

One operators as rectifier and the other as inverter.

Test: Power Electronics - 3 - Question 2

### A single phase full wave regulator feeds R-L load. The best gating signal is

Detailed Solution for Test: Power Electronics - 3 - Question 2

To ensure proper triggering pulse train in necessary because load is R - L.

Test: Power Electronics - 3 - Question 3

### A 3 phase induction motor is fed by a 3 phase ac regulator to change the stator voltage. The variation in speed will be more if

Detailed Solution for Test: Power Electronics - 3 - Question 3

If load torque is constant, the change in speed is very small.

Test: Power Electronics - 3 - Question 4

A cycloconverter cannot give a frequency higher than input frequency.

Detailed Solution for Test: Power Electronics - 3 - Question 4

Step up cycloconverter can give a frequency higher than input frequency.

Test: Power Electronics - 3 - Question 5

A thyristor has internal power dissipation of 40W and is operated at an ambient temperature of 20ºC. If thermal resistance is 1.6º C/W, the junction temperature is

Detailed Solution for Test: Power Electronics - 3 - Question 5

.

Test: Power Electronics - 3 - Question 6

A single phase half wave converter is used to charge a battery of 50 V. The thyristor is continuously fired by dc signal. Input voltage is v = Vm sin ωt. The thyristor will conduct

Detailed Solution for Test: Power Electronics - 3 - Question 6

Thyristor can conduct only when it is forward biased. This occurs only when v > 50 V.

Test: Power Electronics - 3 - Question 7

The symbol in figure is for

Test: Power Electronics - 3 - Question 8

In a 3 phase semiconverter, the firing frequency is

Detailed Solution for Test: Power Electronics - 3 - Question 8

Since the circuit has 3 thyristors, firing frequency is three times the line frequency.

Test: Power Electronics - 3 - Question 9

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

Detailed Solution for Test: Power Electronics - 3 - Question 9

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

Test: Power Electronics - 3 - Question 10

On load tap changer using thyristors can have a maximum of two taps.

Detailed Solution for Test: Power Electronics - 3 - Question 10

Any number of taps are possible.

Test: Power Electronics - 3 - Question 11

Assertion (A): Snubber circuit has an RC series circuit in parallel with SCR

Reason (R): Voltage across a capacitor can not change instantaneously.

Detailed Solution for Test: Power Electronics - 3 - Question 11

Since voltage across capacitor cannot change instantaneously it protects SCR against high .

Test: Power Electronics - 3 - Question 12

In dielectric heating, the thyristor circuits consist of

Detailed Solution for Test: Power Electronics - 3 - Question 12

Input ac is rectified and then converted to high frequency ac.

Test: Power Electronics - 3 - Question 13

Assertion (A): A cycloconverter may be line commutated or forced commutated

Reason (R): A step up cycloconverter requires forced commutation.

Test: Power Electronics - 3 - Question 14

In the below figure the rms voltage across each half of secondary is 200 V. The peak inverse voltage across each of thyristor is

Detailed Solution for Test: Power Electronics - 3 - Question 14

PIV = 2(2 x 200).

Test: Power Electronics - 3 - Question 15

Assertion (A): A GTO circuit is more compact than SCR circuit

Reason (R): A GTO can be turned off by negative gate pulse.

Detailed Solution for Test: Power Electronics - 3 - Question 15

Since commutation circuit is not required, GTO circuit is compact.

Test: Power Electronics - 3 - Question 16

In a single phase full bridge converter (B - 2 connection), the input voltage is v = Vm sin ωt. The output dc voltage for resistive load

Detailed Solution for Test: Power Electronics - 3 - Question 16

SCRs conduct from a to p in each half cycle.

Test: Power Electronics - 3 - Question 17

In a single phase full wave ac regulator, the firing angles in the two half cycles

Test: Power Electronics - 3 - Question 18

As regards single phase dual converter

Test: Power Electronics - 3 - Question 19

To protect an SCR against high di/dt we connect

Detailed Solution for Test: Power Electronics - 3 - Question 19

current through inductance cannot change instantaneously.

Test: Power Electronics - 3 - Question 20

In a parallel inverter

Test: Power Electronics - 3 - Question 21

A silicon controlled switch has :

Detailed Solution for Test: Power Electronics - 3 - Question 21

Anode, cathode, anode gate and cathode gate.

Test: Power Electronics - 3 - Question 22

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

Detailed Solution for Test: Power Electronics - 3 - Question 22

.

Test: Power Electronics - 3 - Question 23

A single phase fully controlled bridge rectifier is fed by a source having inductance. The output voltage during overlap period is

Detailed Solution for Test: Power Electronics - 3 - Question 23

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

Test: Power Electronics - 3 - Question 24

In a semi converter feeding a resistive load, the firing angle is a. Each thyristor conducts for

Detailed Solution for Test: Power Electronics - 3 - Question 24

The conduction is from a to p.

Test: Power Electronics - 3 - Question 25

Between which points does UJT exhibit negative resistance characteristics

## Power Electronics

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## Power Electronics

5 videos|39 docs|63 tests