NON-SINUSOIDAL WA\ 135 



voltage is 6600 volts the voltage from line to neutral is found to 

 be 3850 volts. A third harmonic in the phase voltage is sus- 

 1. and the oscillograph shows that one with a magnitude of 

 L4 per cent, of the fundamental does exi-t. 



What is the copper lo-- in each transformer when there is no 

 load delivered to the high-tension line. Compare this with the 

 full-load copper loss that would be produced in the transformers 

 if their neutral point was not grounded. 



43. A 100U-kw., li-phase. 'J.Veycle, 600-volt rotary converter is 

 supplied with power from a 3-phase, 13,200-volt transmission 

 lint . The high-tension windings of the transformers are con- 

 1 in delta and the low-tension windings are connected to 

 diametrical points of the armature of the rotary. With the low- 

 r en-ion winding of a transformer short-circuited and with 345 

 volts at 25 cycles impressed on the high-tension winding, full- 

 load current, or 25.2 amperes exists in the winding and 3070 

 watts i- -upplied. When the rotary is delivering about full load 

 and the excitation is adjusted for near unit power factor receive 

 the transformer 1120 kw. and the line voltage and current are 

 13,200 volts and 49.8 amperes. Oscillograph records show that 

 at this time there exists across diametrical points of the arma- 

 ture of the rotary a voltage which practically consists of a 

 fundamental and a third harmonic that is 8.5 per cent, of the 

 fundamental 



< 'alrulate the total copper loss in each transform' t. If the 

 low-ten-ion windings had been divided and connected in double V 

 with no connection between their neutral points what would have 

 been the copper loss in each transformer under the same load 

 condition'.' 



44. A3000-kw.,5000-volt,60-cyclealt matin.:-! urnutgrnerator 

 suppli*-- power to a :>-pha-e Iran-mission line through three 

 lOOO-kv.-a. transformers which are connected in V on the low- 

 tension and in delta on the high-tension ndes. With the low- 

 ten-ion winding short-circuited and with i* 240 volts at 60 cycles 

 ssed on the high-ten-ion -idr full-load current exists in the 

 winding^ and 7490 watts is supplied. The ratio of t ran- forma- 

 tion is 2890 to 66,000 volts. Both the neutral point of th- arma- 

 ture win. ling a-nd the neutral point of the low-tension windings 

 of the tran-formers are directly connected to the same bus. 

 When tin- transformers are d J<>.~>() kw. at 0.875 power 



factor and with a line voltage of 66,000 volts they become 



