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 960 turns on its primary winding and 60 turns on its secondary winding. The primary is connected to a 1920 V AC supply. Find the secondary voltage V₂.

N₁ = 960N₂ = 60V₁ = 1920 V

V₂ = V

2.Easy

An ideal transformer has 3000 turns on its primary winding and 120 turns on its secondary winding. The primary is connected to a 10000 V AC supply. Find the secondary voltage V₂.

N₁ = 3000N₂ = 120V₁ = 10000 V

V₂ = V

3.Medium

A single-phase 250 kVA, 4160/480 V transformer operates at its rated load. Treat it as ideal. Find the current I_LV in the low-voltage winding.

S = 250 kVAV₁ = 4160 VV₂ = 480 V

I_LV = A

4.Medium

An ideal transformer with a turns ratio N₁:N₂ = 20:1 has 4800 V applied to its primary winding. An 8 Ω resistor is connected across the secondary winding. Find the primary current I₁.

N₁:N₂ = 20:1V₁ = 4800 VR_L = 8 Ω

I₁ = A

5.Hard

A single-phase 25 kVA transformer has a core loss of 200 W and a copper loss of 300 W at rated load. It supplies 50% of its rated kVA at a power factor of 0.85 lagging. Find the total losses P_loss in watts at this load.

S = 25 kVAP_core = 200 WP_cu,fl = 300 Wx = 0.5pf = 0.85

P_loss = W

6.Hard

A single-phase 500 kVA transformer has a core loss of 1500 W. At rated load and a power factor of 0.8 lagging its efficiency is 98.8%. Find the full-load copper loss P_cu,fl in watts.

S = 500 kVAP_core = 1500 Wpf = 0.8η = 98.8%

P_cu,fl = W

Answer key

1. V₂ = 120 V
2. V₂ = 400 V
3. I_LV = 520.8 A
4. I₁ = 1.5 A
5. P_loss = 275 W
6. P_cu,fl = 3358 W

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