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 1600 turns on its primary winding and 200 turns on its secondary winding. The primary is connected to a 960 V AC supply. Find the secondary voltage V₂.

N₁ = 1600N₂ = 200V₁ = 960 V

V₂ = V

2.Easy

An ideal transformer has 2500 turns on its primary winding and 50 turns on its secondary winding. The primary is connected to an 11500 V AC supply. Find the secondary voltage V₂.

N₁ = 2500N₂ = 50V₁ = 11500 V

V₂ = V

3.Medium

An amplifier with an output resistance of 1152 Ω drives an 8 Ω loudspeaker through an ideal transformer. For maximum power transfer the loudspeaker must look like 1152 Ω from the amplifier. Find the turns ratio a = N₁/N₂.

R_s = 1152 ΩR_L = 8 Ω

a =

4.Medium

A single-phase 500 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 = 500 kVAV₁ = 4800 VV₂ = 240 V

I_LV = A

5.Hard

A single-phase 50 kVA transformer has a core loss of 400 W and a copper loss of 600 W at rated load. At what load S_η,max, in kVA, is its efficiency highest?

S = 50 kVAP_core = 400 WP_cu,fl = 600 W

S_η,max = kVA

6.Hard

A single-phase 150 kVA transformer has a core loss of 1200 W and a copper loss of 3600 W at rated load. It supplies 75% of its rated kVA at a power factor of 0.8 lagging. Find the total losses P_loss in watts at this load.

S = 150 kVAP_core = 1200 WP_cu,fl = 3600 Wx = 0.75pf = 0.8

P_loss = W

Answer key

1. V₂ = 120 V
2. V₂ = 230 V
3. a = 12
4. I_LV = 2083 A
5. S_η,max = 40.82 kVA
6. P_loss = 3225 W

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