ROTARY CONVERTERS 99 



40. A 4-phase, 100-kilowatt, 230-volt rotary converter receives 

 its power from a three-phase, 6600-volt circuit through Scott-con- 

 nected transformers. The low-tension windings are double and 

 are connected in mesh. The efficiency of the rotary at full load 

 and 0.90 power factor is 91.8 per cent. What are the high- and 

 low-tension currents and voltages of the transformers when the 

 rotary delivers its rated load and operates at 0.90 power factor? 



41. A three-phase, 200-kilowatt rotary converter supplies 

 direct current at 1 10 volts. It receives power from a three-phase, 

 6600-volt circuit through three single-phase transformers which 

 have their high-tension windings connected in delta and their low- 

 tension windings connected in Y. At full load and unit power 

 factor the rotary has an efficiency of 93 per cent. What should 

 be the full-load current and voltage ratings of the high -and low- 

 tension windings of the transformers? 



42. A three-phase, 250-kilowatt, 220-volt rotary converter 

 receives power through three single-phase transformers from a 

 3-phase, 2200-volt circuit. The high-tension windings of the 

 transformers are connected in Y and the low-tension windings in 

 delta. The rotary has an overload current capacity of 15 per 

 cent, when operating at 0.9 power factor and at this time the 

 efficiency is 91.8 per cent. What should be the overload current 

 and voltage ratings of the high- and low-tension windings of the 

 transformers? 



43. A three-phase, 300-kilowatt, 500-volt rotary converter 

 receives power through three single-phase transformers from a 

 three-phase, 11,000-volt circuit. Both the high- and low-tension 

 windings of the transformers are connected in Y. When deliver- 

 ing its rated load and operating at 0.85 power factor the rotary 

 has an efficiency of 91.6 per cent. What is the ratio of trans- 

 formation of the transformers? What should be the full-load 

 current ratings of the high- and low-tension windings of the 

 transformers? 



44. A three-phase, 150-kilowatt, 230-volt rotary convert* r 

 receives power through two single-phase transformers from a 

 three-phase, 2200-volt circuit. Both the primary and secondary 

 windings of the transformers are connected in V. Neglecting 

 the losses what should be the cum -nt and voltage ratings of the 

 high- and low-tension windings of the tran-lWiners? 



45. A 6-phase, 1500-kilowatt, 650-volt rotary converter de- 

 livers power to a railway system. It receives power through 



