A single phase, 25 KVA, 2000/200V transformer has iron loss is 350W and full load copper loss is 400W. Calculate the efficiency at unity power factor on full load and half load?
Answers
The efficiency at full load and half loads are 97% and 96.4% respectively.
Given
Apparent power of the transformer = 25000 VA
power factor = 1
=> real power = Apparent power x power factor
= 25000 watts
At full load
Net input = 25000 w
iron loss = 350 w
copper loss = 400 w
=> net loss = 350 + 400 = 750 w
=> output = 25000 - 750 = 24250 w
=> efficiency = output/input = 24250/25000 = 0.97 = 97%
At half load
Net input = 25000/2 = 12500 w
iron loss = 350 w
copper loss = 400/4 = 100 w
=> net loss = 350 + 100 = 450 w
=> output = 12500 - 450 = 12050 w
=> efficiency = output/input = 12050/12500 = 0.964 = 96.4%
Explanation:
A transformer working at unity power factor has an efficiency of 90% at both half load
and at full load of 500W. Determine the efficiency at 75% of full load .
In a 25 KVA,2000/200 V, single ophase transformer, the iron and full load copper losses
are 350W and 400W respectively. Calculate the efficiency at unti power factor on:
(i) Full load (ii) Half full lo