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.

New worksheet Practise online with hints

For teachers: free to print, copy and use in class. Every new worksheet has new values and its own answer key. A link to ExamProblems on your course page is appreciated.

Name: ____________________ Date: ____________

1.Easy

An ideal transformer has 80 turns on its primary winding and 4000 turns on its secondary winding. The primary is connected to a 120 V AC supply. Find the secondary voltage V₂.

N₁ = 80N₂ = 4000V₁ = 120 V

V₂ = V

2.Easy

An ideal transformer has 150 turns on its primary winding and 3750 turns on its secondary winding. The primary is connected to a 120 V AC supply. Find the secondary voltage V₂.

N₁ = 150N₂ = 3750V₁ = 120 V

V₂ = V

3.Medium

An ideal transformer with a turns ratio N₁:N₂ = 2:1 has 460 V applied to its primary winding. A 6 Ω resistor is connected across the secondary winding. Find the primary current I₁.

N₁:N₂ = 2:1V₁ = 460 VR_L = 6 Ω

I₁ = A

4.Medium

A single-phase 25 kVA, 6600/230 V transformer operates at its rated load. Treat it as ideal. Find the current I_HV in the high-voltage winding.

S = 25 kVAV₁ = 6600 VV₂ = 230 V

I_HV = A

5.Hard

A single-phase 500 kVA transformer has a core loss of 1500 W and a copper loss of 4500 W at rated load. It supplies 25% of its rated kVA at a power factor of 0.9 lagging. Find the total losses P_loss in watts at this load.

S = 500 kVAP_core = 1500 WP_cu,fl = 4500 Wx = 0.25pf = 0.9

P_loss = W

6.Hard

A single-phase 25 kVA transformer has a core loss of 100 W. At rated load and a power factor of 0.9 lagging its efficiency is 96.5%. Find the full-load copper loss P_cu,fl in watts.

S = 25 kVAP_core = 100 Wpf = 0.9η = 96.5%

P_cu,fl = W

Answer key

1. V₂ = 6000 V
2. V₂ = 3000 V
3. I₁ = 19.17 A
4. I_HV = 3.788 A
5. P_loss = 1781 W
6. P_cu,fl = 716.1 W

Full step-by-step solutions: practise this topic on examproblems.com.