TRANSFORMERS 13 



55. Calculate (a) the regulation 1 and (b) the efficiency of the 

 transformer No. K for a load of 40 kw at 0.78 power factor 

 and rated voltage. 



56. Calculate (a) the regulation 1 and (b) the efficiency of the 

 transformer No. B for a load of 100 kw. at 0.90 power factor and 

 rated voltage. 



57. Calculate (a) the regulation 1 and (b) the efficiency of the 

 transformer No. C for a load of 460 kw. at 0.91 power factor 

 and rated voltage. 



58. Calculate (a) the regulation 1 and (b) the efficiency of the 

 transformer No. D for a load of 500 kw. at 0.93 power factor 

 and rated voltage. 



59. Calculate (a) the regulation 1 and (b) the efficiency of the 

 transformer No. H for a load of 1100 kw. at unit power factor and 

 rated voltage. 



60. Calculate (a) the regulation 1 and (b) the efficiency of the 

 transformer No. F for a load of 3500 kw. at unit power factor 

 and rated voltage. 



61. Calculate (a) the regulation 1 and (b) the efficiency of the 

 transformer No. I for a load of 5100 kw. at 0.92 



power factor and rated voltage. 



62. The resistance of the high-tension wind- 

 ing (a-c) of a 2:1 auto transformer is 0.072 ohms 

 and that of the low-tension winding (b-c) is 0.035 

 ohms. The leakage reactance of the low-tension 

 winding is 0.106 ohm and that of the remaining 



portion of the winding (a-b) is 0.108 ohm. If ~~p lQ i 

 an electromotive force of 12 volts at the rated 

 frequency is impressed on the high-tension winding and the low- 

 tension winding is short-circuited what will be the current and 

 power taken from the lin 



63. The resistance of the high-tension winding (a-c) see 

 Fig. 1 of a 25-kv.-a., 550:110-volt, auto-transform, r is IHH.VJ 

 ohm and that of the low-trn-i..n winding (b-c) is 0.0042 ohm. 

 Tin- leakage reactance of the winding (a-b) is 0.214 ohm and that 

 of the low-tension winding is 0.0132 ohm. If the winding (a-b) 

 is short-circuited what percentage of the rated voltage should 

 be applied to the low-tm-i.m winding (b-c) in nrdn- that full- 

 load current should exist in the winding-.' What power would be 

 supplied? 



1 N-i:l''-t tin- cxcitnm mrn-nt. 



