Transformers Questions & Answers
Parallel Operation of Single Phase Transformers
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Two single phase transformers A and B are operating in parallel having different impedance and identical x/r ratio. Also impedance of A is more than that of B,then A
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Wrong!

Two single phase transformers A and B are operating in parallel having different impedance and identical x/r ratio. Then
Correct!
Wrong!

For a deltastar three phase transformer,if the transformation ratio is ‘x:1’, then how much percent of output will be improved?
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Two single phase transformers A and B are operating in parallel having different impedance and identical x/r ratio. Impedance of A is Za and impedance of B is Zb , both sharing a load of Sl. Then the load shared by transformer B is
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In three phase supply, the voltage phases are displaced by ________ and in two phase by _______
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For a stardelta three phase transformer,if the transformation ratio is ‘x:1’, then how much percent of output will be ?
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Which if the conditions is must be fulfilled for a satisfactory parallel operation of transformers?
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Two single phase transformers A and B are operating in parallel having same impedance. But the x/r ratio of them are not equal. Then total kVA output of the output will be
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Wrong!

Two single phase transformers A and B are operating in parallel having different impedance and identical x/r ratio. Also impedance of A is more than that of B,then
Correct!
Wrong!

A 2000/1000/500 three winding transformer is to be used as auto transformer with supply of 3000 V. Two loads of 1050 kVA at 3500V, and other one at 180 kVA at 1000V. The circuit representing the mentioned application is
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Wrong!

Two single phase transformers A and B are operating in parallel having different impedance and identical x/r ratio. Impedance of A is Za and impedance of B is Zb , both sharing a load of Sl. Then the load shared by transformer A is
Correct!
Wrong!

I. reliable loading
II.increased capacity of power system
III.reducing the capacity of substation
Which of the following is a shortcoming for using parallel connected transformers?
II.increased capacity of power system
III.reducing the capacity of substation
Which of the following is a shortcoming for using parallel connected transformers?
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Two single phase transformers A and B are operating in parallel having same impedance. But the x/r ratio of them are not equal and xa > xb. Then
Correct!
Wrong!

Identify the correct order for the voltage transformation for the threephase transformers.
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Operating transformers in parallel gives the advantage of
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A. Positive sequence components – 5th harmonic component
B. Negative sequence components – 7th harmonic component
C. Zero sequence components – 3rd harmonic component
Above are the matching made for the harmonics and the associated harmonic component, then the correct marking is
B. Negative sequence components – 7th harmonic component
C. Zero sequence components – 3rd harmonic component
Above are the matching made for the harmonics and the associated harmonic component, then the correct marking is
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Transformer operating in parallel will share a common load in the best possible manner if
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A 2000/1000/500 three winding transformer is to be used as auto transformer with supply of 3000 V. Two loads of 1050 kVA at 3500V, and other one at 180 kVA at 1000V. The total kVA supplied will be
Correct!
Wrong!
