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 1500 turns on its primary winding and 150 turns on its secondary winding. The primary is connected to a 2400 V AC supply. Find the secondary voltage V₂.

N₁ = 1500N₂ = 150V₁ = 2400 V

V₂ = V

2.Easy

An ideal transformer has 150 turns on its primary winding and 1500 turns on its secondary winding. The primary is connected to a 110 V AC supply. Find the secondary voltage V₂.

N₁ = 150N₂ = 1500V₁ = 110 V

V₂ = V

3.Medium

An ideal transformer with a turns ratio N₁:N₂ = 10:1 has 2300 V applied to its primary winding. A 12 Ω resistor is connected across the secondary winding. Find the primary current I₁.

N₁:N₂ = 10:1V₁ = 2300 VR_L = 12 Ω

I₁ = A

4.Medium

A single-phase 250 kVA, 6600/230 V transformer operates at its rated load. Treat it as ideal. Find the current I_LV in the low-voltage winding.

S = 250 kVAV₁ = 6600 VV₂ = 230 V

I_LV = A

5.Hard

A single-phase 250 kVA transformer has a core loss of 1000 W. At rated load and a power factor of 0.9 lagging its efficiency is 98.8%. Find the full-load copper loss P_cu,fl in watts.

S = 250 kVAP_core = 1000 Wpf = 0.9η = 98.8%

P_cu,fl = W

6.Hard

A single-phase 75 kVA transformer has a core loss of 300 W. At rated load and a power factor of 0.85 lagging its efficiency is 97%. Find the full-load copper loss P_cu,fl in watts.

S = 75 kVAP_core = 300 Wpf = 0.85η = 97%

P_cu,fl = W

Answer key

1. V₂ = 240 V
2. V₂ = 1100 V
3. I₁ = 1.917 A
4. I_LV = 1087 A
5. P_cu,fl = 1733 W
6. P_cu,fl = 1672 W

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