Transformer MCQs Part 32

Electrical Engineering MCQs on Transformer Part 32 – Transformers Multiple Choice Questions

The iron losses and full load Cu losses in a 100 kVA transformer are 400 and 1000 W respectively. The efficiency of transformer at full load at 0.85 PF lagging will be

The iron losses and full load Cu losses in a 100 kVA transformer are 400 and 1000 W respectively. The efficiency of transformer at full load at 0.85 PF lagging will be:

1. 93.88%
2. 95.72%
3. 98.61%
4. 99.03%

Correct answer: 3. 98.37%

Explanation:

Solution:

Full load output = kVA * cos Φ = 100 * 0.85 = 85 kW

Total Full load losses = 400 + 1000 = 1400 W = 1.4 kW

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Full load input = 85 kW + 1.4 kW = 86.4 kW

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Full load efficiency = (Full load output/Full load input) * 100

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Full load efficiency = 85/86.4 * 100

Full load efficiency = 98.37%

Transformer oil used in Transformer Provides

Transformer oil used in Transformer provides:

1. Cooling
2. Insulation
3. Both of these
4. None of these

Correct answer: 3. Both of these

Current transformers are connected in

Current transformers are connected in:

1. Series
2. Parallel
3. Any of above
4. None of these

Correct answer: 1. Series

The ideal transformer will have maximum efficiency for which condition

The ideal transformer will have maximum efficiency for which condition

1. Cannot be determined
2. Copper loss < iron loss
3. Copper loss = iron loss
4. Copper loss > iron loss

Correct answer: 3. Copper loss = iron loss

The maximum flux produced in core of transformer is

The maximum flux produced in core of transformer is:

1. Inversely proportional to primary voltage
2. Inversely proportional to supply frequency
3. Directly proportional to supply frequency
4. None of these

Correct answer: 2. Inversely proportional to supply frequency