Transformers worksheet with answers

Free printable Transformers worksheet: 6 problems from easy to exam level, with an answer key. Print it or save it as a PDF.

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1.Easy

An ideal transformer has 2400 turns on its primary winding and 60 turns on its secondary winding. The primary is connected to a 9200 V AC supply. Find the secondary voltage V₂.

N₁ = 2400N₂ = 60V₁ = 9200 V

V₂ = V

2.Easy

An ideal transformer has 100 turns on its primary winding and 2500 turns on its secondary winding. The primary is connected to a 230 V AC supply. Find the secondary voltage V₂.

N₁ = 100N₂ = 2500V₁ = 230 V

V₂ = V

3.Medium

A single-phase 100 kVA, 11000/400 V transformer operates at its rated load. Treat it as ideal. Find the current I_LV in the low-voltage winding.

S = 100 kVAV₁ = 11000 VV₂ = 400 V

I_LV = A

4.Medium

An ideal transformer with a turns ratio N₁:N₂ = 5:1 has 1200 V applied to its primary winding. A 10 Ω resistor is connected across the secondary winding. Find the primary current I₁.

N₁:N₂ = 5:1V₁ = 1200 VR_L = 10 Ω

I₁ = A

5.Hard

A single-phase 25 kVA transformer has a core loss of 200 W and a copper loss of 500 W at rated load. It supplies 50% of its rated kVA at a power factor of 0.8 lagging. Find the total losses P_loss in watts at this load.

S = 25 kVAP_core = 200 WP_cu,fl = 500 Wx = 0.5pf = 0.8

P_loss = W

6.Hard

A single-phase 150 kVA transformer has a core loss of 600 W. At rated load and a power factor of 0.8 lagging its efficiency is 99%. Find the full-load copper loss P_cu,fl in watts.

S = 150 kVAP_core = 600 Wpf = 0.8η = 99%

P_cu,fl = W

Answer key

1. V₂ = 230 V
2. V₂ = 5750 V
3. I_LV = 250 A
4. I₁ = 4.8 A
5. P_loss = 325 W
6. P_cu,fl = 612.1 W

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