TRANSFORMERS 7 



netic circuit is halved? Assume that originally the iron and 

 copper losses are equal. 



32. In a given transformer the ratio of the iron losses to the 

 copper losses at full load is 0.7. Another transformer with the 

 same rating has a magnetic circuit of the same length but of 25 

 per cent, greater cross-section, due to which the mean length of 

 one turn of the winding is 10 per cent, greater. Both transformers 

 are wound with the same size wire. The second transformer 

 is designed so as to have the same maximum flux density as the 

 first. What is the ratio of the total losses at full load, and what 

 is the ratio of the iron losses to the copper losses in the second 

 transformer at full load? Compare the amounts of copper in 

 the two transformers. Both transformers are designed for the 

 same voltage. 



33. Two transformers have identical magnetic cores and the 

 same rated output. Both are wound for the same voltage but in 

 the first the iron losses are 25 per cent, greater than in the second 

 due to a higher flux density. In the first transformer the ratio of 

 the iron losses to the copper losses at full load is 0.7. Both 

 transformers have the same size of wire in their windings, but the 

 mean length of one turn is 5 per cent, greater in the second than in 

 the first . What is the ratio of the iron losses to the copper losses 

 at full load in the second transformer? What is the ratio of the 

 total losses at full load in the two transformers? Compare the 

 amounts of copper in the two transformers. Assume that the iron 

 losses vary as the 1.7 power of the flux density. 



34. Two transformers have identical magnetic cores and the 

 same rated output. Bothare wound forthesame voltage but the 

 fir-t has l.~> per cent, mure turn- in all of its coils than the second, 

 due to which t he mean length of one turn is 5 per cent, greater in 

 the fir-t. The windings of each are of the same -i/.e wire. Assume 

 that the iron losses vary as the 1.7 power of the flux density. 

 The ratio of the iron lo>ses to the copper losses at full load is 0.7 

 in the fir>! t ran-former. What i- the ratio of the iron losses to 

 the copper losses at full load in the - < -mid transform. T ? What is 

 the ratio of the total losses at full load in the two transformers? 



35. In a given transformer tin- ratio .,!' the iron losses to the 

 copper losses at full load i- n.7.~>. Another transformer with the 

 same radiatini: capacity has a magnetic core of the -ame length 

 hut with a cross-section l.~> p.-r cent larger The winding of the 

 second transformer is designed so that the iron losses -are one- 



