Page 581 - Basic Electrical Engineering

Given,

kVA = 10
VA = 10 × 1000
V I = 10 × 1000
2 2

This current I is passing through the equivalent resistance, R″ = 1.125 Ω.
e
2
2
Total copper loss = R″ = (50) × 1.125 = 2.8kW.
e

Example 6.10 A 25 kVA, 2000/200 V transformer has constant loss, i.e.,
iron loss of 350 W and full-load copper loss called the variable loss of 400

W. Calculate the efficiency of the transformer at full load and at half load 0.8
power factor lagging.

Solution:

Output in kVA = 25, output in kW = kVA cosϕ = 25 × 0.8 = 20 kW

Efficiency,

Output in Watts =20× 1000W

Core loss or iron loss = 350 W