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 150 turns on its secondary winding. The primary is connected to a 1920 V AC supply. Find the secondary voltage V₂.

N₁ = 2400N₂ = 150V₁ = 1920 V

V₂ = V

2.Easy

An ideal transformer has 1000 turns on its primary winding and 25 turns on its secondary winding. The primary is connected to a 9200 V AC supply. Find the secondary voltage V₂.

N₁ = 1000N₂ = 25V₁ = 9200 V

V₂ = V

3.Medium

A single-phase 100 kVA, 4800/240 V transformer operates at its rated load. Treat it as ideal. Find the current I_LV in the low-voltage winding.

S = 100 kVAV₁ = 4800 VV₂ = 240 V

I_LV = A

4.Medium

An ideal transformer with a turns ratio N₁:N₂ = 4:1 has 960 V applied to its primary winding. A 30 Ω resistor is connected across the secondary winding. Find the primary current I₁.

N₁:N₂ = 4:1V₁ = 960 VR_L = 30 Ω

I₁ = A

5.Hard

A single-phase 200 kVA transformer has a core loss of 1200 W. At rated load and a power factor of 0.95 lagging its efficiency is 99%. Find the full-load copper loss P_cu,fl in watts.

S = 200 kVAP_core = 1200 Wpf = 0.95η = 99%

P_cu,fl = W

6.Hard

A single-phase 50 kVA transformer has a core loss of 250 W. At rated load and a power factor of 0.8 lagging its efficiency is 98%. Find the full-load copper loss P_cu,fl in watts.

S = 50 kVAP_core = 250 Wpf = 0.8η = 98%

P_cu,fl = W

Answer key

1. V₂ = 120 V
2. V₂ = 230 V
3. I_LV = 416.7 A
4. I₁ = 2 A
5. P_cu,fl = 719.2 W
6. P_cu,fl = 566.3 W

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