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Transformer Calculations Quiz Questions
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Question 1 of 8
1. Question
1 pointsA Transformer has 1000 turns on the primary winding ans has 100 turns in the secondary windings. If the voltage of 250V is applied to the primary windings. What will be the secondary voltage of the transformer:
Correct
Transformer Primary winding number of turns (N1)= 1000 turnsTransformer Secondary winding number of turns (N2)= 100 turns
Transformer Primary winding voltage (V1)= 250V
Transformer Secondary winding voltage (V2)= X V
(N1/N2) = (V1/V2)
(1000/100) = (250/X)
X = (250/10) = 25VAnswer = 25V
Incorrect
Transformer Primary winding number of turns (N1)= 1000 turnsTransformer Secondary winding number of turns (N2)= 100 turns
Transformer Primary winding voltage (V1)= 250V
Transformer Secondary winding voltage (V2)= X V
(N1/N2) = (V1/V2)
(1000/100) = (250/X)
X = (250/10) = 25VAnswer = 25V

Question 2 of 8
2. Question
1 pointsA Transformer has 500 turns on the primary winding ans has 100 turns in the secondary windings. Find the Transformer ratio:
Correct
Number of Turns in Primary Winding (N1) = 500
Number of Turns in Secondary Winding (N2) = 100
Transformer Ratio = (N1/N2) = 500/100 = 5:1Answer: 5:1
Incorrect
Number of Turns in Primary Winding (N1) = 500
Number of Turns in Secondary Winding (N2) = 100
Transformer Ratio = (N1/N2) = 500/100 = 5:1Answer: 5:1

Question 3 of 8
3. Question
1 pointsIf the primary and secondary voltage ratings of a 3phase transformer are 1 kV and 120 V respectively. Transformer has 500 primary turns then how many secondary turns are present in 3phase transformer:
Correct
Transformer Primary Voltage (V1) = 1kV = 1000 volts
Transformer Secondary Voltage (V2) = 120 V
Number of Primary Turns (N1) = 500
Number of Secondary Turns (N2) = X(V1/V2) = (N1/N2)
(1000/120) = (500/X)
X = 60 turnsAnswer = 60 turns
Incorrect
Transformer Primary Voltage (V1) = 1kV = 1000 volts
Transformer Secondary Voltage (V2) = 120 V
Number of Primary Turns (N1) = 500
Number of Secondary Turns (N2) = X(V1/V2) = (N1/N2)
(1000/120) = (500/X)
X = 60 turnsAnswer = 60 turns

Question 4 of 8
4. Question
1 pointsIf the transformer ratio is in the order of 1:16, what will the ratio of the primary and secondary currents
Correct
Transformer Ratio (N1/N2) = 1:16Ratio of Primary and Secondary Currents = (I1/I2)
(N1/N2) = (I2/I1)
(1/16) = (I2/I1)
(I1/I2) = 16/1Answer: 16:1
Incorrect
Transformer Ratio (N1/N2) = 1:16Ratio of Primary and Secondary Currents = (I1/I2)
(N1/N2) = (I2/I1)
(1/16) = (I2/I1)
(I1/I2) = 16/1Answer: 16:1

Question 5 of 8
5. Question
1 pointsA 1Phase Transformer having voltage rating of 1 kV primary / 100V secondary. Current flowing through the secondary windings is 10 A with 0.8 lagging power factor. Calculate the Power or rating of the secondary winding of the transformer:
Correct
Secondary Voltage of Transformer = 100V
Current flowing through the secondary winding = 10 A
Power factor = 0.8
Power P = Voltage x Current x Power factor
P = 100 x 10 x0.8 = 800 wattAnswer = 800 watts
Incorrect
Secondary Voltage of Transformer = 100V
Current flowing through the secondary winding = 10 A
Power factor = 0.8
Power P = Voltage x Current x Power factor
P = 100 x 10 x0.8 = 800 wattAnswer = 800 watts

Question 6 of 8
6. Question
1 pointsIf the copper loss of a transformer is 400 watts at full load. If the load on the transformer is reduced to half. Then what will the copper loss in the transformer:
Correct
Copper loss = I^{2}R loss
R remains constant irrespective of the load on the transformer.
Therefore copper loss directly proportional to I^{2}P _{full load} = 400 watts
P _{half load} = ( 400/ 4) watts = 100 wattsAnswer = 100 watts
Incorrect
Copper loss = I^{2}R loss
R remains constant irrespective of the load on the transformer.
Therefore copper loss directly proportional to I^{2}P _{full load} = 400 watts
P _{half load} = ( 400/ 4) watts = 100 wattsAnswer = 100 watts

Question 7 of 8
7. Question
1 pointsCalculate the rating of the 3phase transformer having secondary voltage 100V current flowing through the secondary winging is 10 A with power factor of 0.9
Correct
Power P =Sqrt (3) x V x I x Cos (phi)
P = 1.732 x 100 x 10 x0.9
P = 1558 wattsAnswer = 1558 watts
Incorrect
Power P =Sqrt (3) x V x I x Cos (phi)
P = 1.732 x 100 x 10 x0.9
P = 1558 wattsAnswer = 1558 watts

Question 8 of 8
8. Question
1 pointsThe Secondary Current in a transformer is 6 A and transformation ratio Primary to secondary is 1:10
Correct
Secondary Current = 6A
Transformer ratio (N_{1}/N_{2}) = (1/10)
(N_{1}/N_{2}) = (I_{2}/I_{1})
(1/10) = (6/I_{1})
I_{1} = 60Answer = 60 A
Incorrect