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 4800 V AC supply. Find the secondary voltage V₂.

N₁ = 2400N₂ = 60V₁ = 4800 V

V₂ = V

2.Easy

An ideal transformer has 150 turns on its primary winding and 300 turns on its secondary winding. The primary is connected to a 110 V AC supply. Find the secondary voltage V₂.

N₁ = 150N₂ = 300V₁ = 110 V

V₂ = V

3.Medium

A single-phase 100 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 = 100 kVAV₁ = 6600 VV₂ = 230 V

I_LV = A

4.Medium

An ideal transformer with a turns ratio N₁:N₂ = 4:1 has 920 V applied to its primary winding. An 8 Ω resistor is connected across the secondary winding. Find the primary current I₁.

N₁:N₂ = 4:1V₁ = 920 VR_L = 8 Ω

I₁ = A

5.Hard

A single-phase 500 kVA transformer has a core loss of 1500 W. At rated load and a power factor of 0.95 lagging its efficiency is 98.8%. Find the full-load copper loss P_cu,fl in watts.

S = 500 kVAP_core = 1500 Wpf = 0.95η = 98.8%

P_cu,fl = W

6.Hard

A single-phase 500 kVA transformer has a core loss of 4000 W and a copper loss of 10000 W at rated load. It supplies 25% of its rated kVA at a power factor of 0.8 lagging. Find the total losses P_loss in watts at this load.

S = 500 kVAP_core = 4000 WP_cu,fl = 10000 Wx = 0.25pf = 0.8

P_loss = W

Answer key

1. V₂ = 120 V
2. V₂ = 220 V
3. I_LV = 434.8 A
4. I₁ = 7.188 A
5. P_cu,fl = 4269 W
6. P_loss = 4625 W

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