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 worksheetPractise 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
N1​ = 250N2​ = 500230 VV2​ = ?

An ideal transformer has 250 turns on its primary winding and 500 turns on its secondary winding. The primary is connected to a 230 V AC supply. Find the secondary voltage V2.

N1 = 250N2 = 500V1 = 230 V
V2 = V
2.Easy
N1​ = 600N2​ = 150480 VV2​ = ?

An ideal transformer has 600 turns on its primary winding and 150 turns on its secondary winding. The primary is connected to a 480 V AC supply. Find the secondary voltage V2.

N1 = 600N2 = 150V1 = 480 V
V2 = V
3.Medium
7200 V240 VIHV​ = ?ILV​50 kVA

A single-phase 50 kVA, 7200/240 V transformer operates at its rated load. Treat it as ideal. Find the current IHV in the high-voltage winding.

S = 50 kVAV1 = 7200 VV2 = 240 V
IHV = A
4.Medium
10000 V400 VIHV​ILV​ = ?500 kVA

A single-phase 500 kVA, 10000/400 V transformer operates at its rated load. Treat it as ideal. Find the current ILV in the low-voltage winding.

S = 500 kVAV1 = 10000 VV2 = 400 V
ILV = A
5.Hard
pf 0.925 kVA, η = 97.5%

A single-phase 25 kVA transformer has a core loss of 200 W. At rated load and a power factor of 0.9 lagging its efficiency is 97.5%. Find the full-load copper loss Pcu,fl in watts.

S = 25 kVAPcore = 200 Wpf = 0.9η = 97.5%
Pcu,fl = W
6.Hard
pf 0.85500 kVA, η = 98.2%

A single-phase 500 kVA transformer has a core loss of 4000 W. At rated load and a power factor of 0.85 lagging its efficiency is 98.2%. Find the full-load copper loss Pcu,fl in watts.

S = 500 kVAPcore = 4000 Wpf = 0.85η = 98.2%
Pcu,fl = W

Answer key

  1. 1. V2 = 460 V
  2. 2. V2 = 120 V
  3. 3. IHV = 6.944 A
  4. 4. ILV = 1250 A
  5. 5. Pcu,fl = 376.9 W
  6. 6. Pcu,fl = 3790 W

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