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MCQ's Power Transformer Fundamentals

If you think you have a good understanding of Power Transformer Fundamentals, challenge yourself and take the quiz.

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Question 1 of 29

Q.1 In wye connection, one of the terminals of each phase winding is: 

A

shorted with each other to ground

B

connected to adjacent phase winding terminal

C

both

Question 2 of 29

Q.2 In the delta-connection each phase winding terminal is:

A

connected to its adjacent phase terminal

B

shorted with each other to ground

C

both

Question 3 of 29

Q.3 What is the relation of a phase voltage and a line voltage in delta-connection?

A

VL = VØ

B

VL = √3VØ

C

VL = √2VØ

Question 4 of 29

Q.4 The phase shift between line voltage and phase voltage in wye connection is:

A

0°

B

30°

C

120°

Question 5 of 29

Q.5 If the line voltage is 4160V, what will be its phase voltage in wye connection?

A

4160 V

B

2491.5 V

C

2401.7 V

Question 6 of 29

Q.6 In delta connection, phase B angle is 240°, then its line voltage has ____ angle.

A

240°

B

210°

C

270°

Question 7 of 29

Q.7 In dot convention, if the current is entering in the dot on primary side, then the current from the secondary side dot should

A

Exits

B

No change in current direction

C

None of these

Question 8 of 29

Q.8 The nodal equation at phase A of delta connection is represented as:

A

ILA + IØC = IØA

B

ILA - IØC = IØA

C

ILA - IØA = IØC

Question 9 of 29

Q.9 What is the relation of a phase current and a line current in the wye connection?

A

IL = IØ

B

IL = √3IØ

C

IL = √2IØ

Question 10 of 29

Q.10 What is the phase angle of B in ABC sequence?

A

240°

B

120°

C

0°

Question 11 of 29

Q.11 For ABC sequence, which statement is true?

A

Phase A is taken as reference and angle is measured in clock wise direction

B

Phase A is taken as reference and angle is measured in counter clock wise direction

C

Phase C is taken as reference and angle is measured in counter clock wise direction

Question 12 of 29

Q.12 What causes the line current to be 1.73 (√3) times of phase current in delta connection?

A

Phase shift of 120 degrees between two phases

B

Algebraic sum of two phases

C

None of the above

Question 13 of 29

Q.13 In delta connection, the magnitude of line current is 1200 Amps, what will be its phase current?

A

1200 Amps

B

848.5 Amps

C

692.8 Amps

Question 14 of 29

Q.14 Which statement is true for delta connection?

A

Line current leads phase current by 30°

B

Line current lags phase current by 120°

C

Line current lags phase current by 30°

Question 15 of 29

Q.15 Delta connection shows a balance system as:

A

It’s line currents have phase shifts of 120° and are equal in magnitude

B

It’s phase currents have phase shifts of 120° and are equal in magnitude

C

Both (a) and (b)

Question 16 of 29

Q.16 What is the relation of Line voltage and phase voltage in delta-connection?

A

VL = VØ

B

VL = √3VØ

C

VL = √2VØ

Question 17 of 29

Q.17 The closed form phasor diagram in delta connection helps us understand:

A

physical connection of transformer

B

winding losses of transformer

C

tap position of transformer

Question 18 of 29

Q.18 If the line voltage is written as VCA, then its phasor:

A

starts from point C and ends at point A

B

starts from point A and ends at point C

C

None

Question 19 of 29

Q.19 In the delta wye transformer, DAC shows which type of connection:

A

Dyn11

B

Dyn1

C

Dy1

Question 20 of 29

Q.20 In the delta wye transformer Dyn1 connection can also be represented as:

A

DAC

B

DAB

C

None of these

Question 21 of 29

Q.21 In delta wye transformer, DAC is read as:

A

The polarity side of winding A is connected to non-polarity side of winding C

B

The polarity side of winding C is connected to non-polarity side of winding A

C

None of these

Question 22 of 29

Q.22 In Dyn11, n represents:

A

LV (Wye) side have neutral bushing

B

LV (Wye) side neutral is grounded

C

Both (a) and (b)

Question 23 of 29

Q.23 In Dyn11, ‘D’ and ‘y’ represents:

A

HV and LV winding respectively

B

LV and HV winding respectively

C

None of these

Question 24 of 29

Q.24 In Dyn1, ‘1’ represents:

A

LV reference quantity lags HV reference quantity by 30°

B

LV reference quantity leads HV reference quantity by 330°

C

Both (a) and (b)

Question 25 of 29

Q.25 Wye connection is also known as:

A

Star connection

B

4 wire system

C

Y connection

D

All of the above

Question 26 of 29

Q.26 In Wye connection, line to line voltage across ‘BC’ (VLL-BC) is equal to: 

A

VΦB - VΦC

B

VΦC - VΦB

C

All of the above

Question 27 of 29

Q.27 The rule for a balanced 3 phase system is:

A

All 3 phases should be equal in magnitude

B

All 3 phases should have a phase displacement of 120° with each other

C

Phase sequence should be either ABC or ACB

D

All of the above

Question 28 of 29

Q.28 Three-phase short circuit current is calculated as:

A

Isc = MVASC / (√3 * KV)

B

Isc = MVASC / (√3 * KV * 10³)

C

None of the above

Question 29 of 29

Q.29 The type of fault that can occur during a 3 phase unbalance fault is a

A

Line to ground fault

B

Line to line fault

C

Double line to ground fault

D

All of the above

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