A transformer is rated at 90 kVA. At full load its copper losses are 1100W and its iron losses are 950 W. The percentage efficiency of transformer at full load, unity power factor will be A 96.54% B 97.77% C 98.74% D none of above?

Question

Answer

Calculation of Efficiency of Transformer at Full Load, Unity Power Factor

Given:
Transformer rating = 90 kVA
Copper losses = 1100 W
Iron losses = 950 W

Copper Losses:
Copper losses are given as 1100 W
Power loss = I^2R
where I = full load current and R = resistance of copper winding

Therefore, I^2R = 1100
Let's assume the resistance of copper winding is 'x' ohms
Then, I^2x = 1100
I^2 = 1100/x

Iron Losses:
Iron losses are given as 950 W

Total Losses:
Total losses = Copper losses + Iron losses
Total losses = 1100 + 950 = 2050 W

Output:
Output = Transformer rating = 90 kVA

Efficiency:
Efficiency = Output / (Output + Total losses)
Efficiency = 90000 / (90000 + 2050)
Efficiency = 0.9777 or 97.77%

Therefore, the correct answer is option B - 97.77%.

Answer

A

Similar GATE Doubts

A Transformer is rated at 100 KVA. At full load its copper loss is 1200 W and its iron loss is 850 W. Calculate the load (in KV

Full load efficiency of a 100 kVA transformer is 98%. Maximum efficiency occurs at (3/4)×full load. The power factor is 0.8 lagging at all loads. ?) 1.Estimate the copper loss (in W) at full load. 2.Estimate the iron loss (in W). 3.Estimate the percentage efficiency in half load.?

One transformer is rated at 400 KVA & has per unit impedance of (0.02 + j0.08) p.u. and other is rated at 800 KVA & has per unit impedance of (0.20 + j0.08) p.u. Both transformers are connected in parallel to the load. Find the maximum load (in KV

Top Courses for GATE

Suggested Free Tests

Related Content

Mock Test Series

Subject-wise Courses

Other Engg Branches

Related Exams

Company