The efficiency of a 100 kVA transform is 0.98 at full as

The efficiency of a 100 kVA transform is 0.98 at full as well as at half load. For this transformer at full load the copper loss is

1. less than core loss
2. equal to core loss
3. more than core loss
4. none of these

For 100 kV transformer, we have
At full load (η = 0.98),

0.98 =	100
	100 + W_cu + W_co

⇒ W_cu + W_co + 100 =	100
	0.98

⇒ W_cu + W_co = 2.04 ...(i)
At half load,

0.98 =	50
	50 + W_cu/4 + W_co

⇒	W_cu	+ W_co =	50	− 50
	4		0.98

⇒	W_cu	+ W_co = 1.02 ...(ii)
	4

From equations (i) and (ii), we get

W_cu	= 1.02
4

⇒ W_cu = 1.36 kW
W_core = 0.68 kW
Hence at full load copper loss is more than core loss.