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Test: Voltage Regulation Of Transformer


10 Questions MCQ Test Electrical Machines | Test: Voltage Regulation Of Transformer


Description
This mock test of Test: Voltage Regulation Of Transformer for Electrical Engineering (EE) helps you for every Electrical Engineering (EE) entrance exam. This contains 10 Multiple Choice Questions for Electrical Engineering (EE) Test: Voltage Regulation Of Transformer (mcq) to study with solutions a complete question bank. The solved questions answers in this Test: Voltage Regulation Of Transformer quiz give you a good mix of easy questions and tough questions. Electrical Engineering (EE) students definitely take this Test: Voltage Regulation Of Transformer exercise for a better result in the exam. You can find other Test: Voltage Regulation Of Transformer extra questions, long questions & short questions for Electrical Engineering (EE) on EduRev as well by searching above.
QUESTION: 1

A 10 kVA, 400/200 V, 1-phase transformer with 2% resistance and 2% leakage reactance. It draws steady short circuit current at angle of

Solution:

 The power factor angle will be atan(x/r)=45°.

QUESTION: 2

While conducting open circuit test and short circuit test on a transformer, status of low-voltage and high-voltage windings will be such that in

Solution:

In conducting short circuit test, l.v. winding is short circuited. In OC test h.v. is open circuited.

QUESTION: 3

While conducting testing on the single phase transformer, one of the student tries to measure the resistance by putting an ammeter across one terminal of primary and other to secondary, the reading obtained will be

Solution:

As the primary and secondary are physically isolated, the impedance will be infinite for not electrically connected circuit.

QUESTION: 4

If the per unit leakage impedance for the primary of a transformer is ‘x’ on the given rated base value. If the voltage and volt-amperes are doubled, then the changed per unit impedance will be
Solution:

 pu(new base)=(x)*(MVA(new)/MVA(old))*(kV(old)/kV(new))^2
=x*2*(1/4)
=0.5x.

QUESTION: 5

The voltage regulation for transformer is given by
Solution:

Voltage regulation is the change in secondary voltage with secondary rated voltage.

QUESTION: 6

 While estimating voltage regulation of a transformer, keeping
Solution:

V.R. is calculated keeping the primary constant because then the core flux will change and the change of secondary voltage can not be fixed.

QUESTION: 7

A 200/400 V single phase transformer has leakage impedance z= r+jx. Then we can expect magnitude of load pf of ____ at zero voltage regulation.
Solution:

ZVR occurs at the leading pf of load at x/r.

QUESTION: 8

A 200/400 V single phase transformer has leakage impedance z= r+jx. Then we can expect magnitude of load pf of ____ at zero voltage regulation.
Solution:

Cosθ = x/z for the transformer at zero V.R.

QUESTION: 9

 If the pu impedance of a single phase transformer is 0.01+j0.05, then its regulation at p.f. of 0.8 lagging will be
Solution:

V.R. = (r(pu)*cosθ+x(pu)*sinθ)*100 % = (0.01*0.8 + 0.05*0.6)*100 = 3.8%

QUESTION: 10

The transformer phasor diagram under the short circuit can be identified as
Solution:

For the short-circuit condition of a transformer, voltage across the secondary will be voltage drop across winding only.

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