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MCQ's Power Transformer Fundamentals Assessment

This course aims to teach you all the fundamentals of Power Transformer including transformer winding connections Delta Wye and Wye Wye, how voltage and current quantities are related by phasor diagram, and methods to represent each transformer connections. If you think you have a good understanding of Power Transformer, 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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