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 2000 turns on its primary winding and 50 turns on its secondary winding. The primary is connected to a 9600 V AC supply. Find the secondary voltage V₂.

N₁ = 2000N₂ = 50V₁ = 9600 V

V₂ = V

2.Easy

An ideal transformer has 60 turns on its primary winding and 600 turns on its secondary winding. The primary is connected to a 240 V AC supply. Find the secondary voltage V₂.

N₁ = 60N₂ = 600V₁ = 240 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

A single-phase 25 kVA, 4800/240 V transformer operates at its rated load. Treat it as ideal. Find the current I_HV in the high-voltage winding.

S = 25 kVAV₁ = 4800 VV₂ = 240 V

I_HV = A

5.Hard

A single-phase 500 kVA transformer has a core loss of 2500 W and a copper loss of 3750 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 = 2500 WP_cu,fl = 3750 Wx = 0.25pf = 0.9

P_loss = W

6.Hard

A single-phase 500 kVA transformer has a core loss of 2000 W and a copper loss of 3000 W at rated load. At what load S_η,max, in kVA, is its efficiency highest?

S = 500 kVAP_core = 2000 WP_cu,fl = 3000 W

S_η,max = kVA

Answer key

1. V₂ = 240 V
2. V₂ = 2400 V
3. I_LV = 434.8 A
4. I_HV = 5.208 A
5. P_loss = 2734 W
6. S_η,max = 408.2 kVA

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