SYNCHRONOUS GENERATORS 39 



pole per ampere. The field poles are each wound with 79.5 

 turns. The data for the open-circuit characteristic are: 



Fit-Id ampm tarns per pole Open-circuit terminal voltage 



6,000 

 10,000 

 12,000 

 14,000 



4330 

 5460 

 5800 



lilWO 



What i the regulation of this generator when delivering 30 

 per cent, overload current at unit power factor? 



(a) Assume that the cross-magnetizing and demagnetizing 

 ampere turns act on magnetic circuits of the same reluctance as 

 that of the resultant field. This is a modification of the general 

 method. 



(b) Assume that the cross-magnetizing ampere turns act on a 

 magnetic circuit whose reluctance is determined by the lower 

 part of the saturation curve, and that the demagnetizing ampere 

 turns act on the same magnetic circuit as do the impressed field 

 ampere turns. This is the Blondel method. 



58. A 3-phase, Y-connected alternating-current generator is 

 rated to deliver 1000 kv.-a. at 13,800 volts. The armature 

 has an effective resistance of 2.18 ohms per phase. The data for 

 the open-circuit characteristic and the full-load current satura- 

 tion curve at zero power factor an : 



What is the regulation tW MM induct i\-r load <f :>n 

 at 0.85 power factor? 



69. A 3-phase, water-wheel generator is rated to deliver 5000 

 kv.-a. at 6600 volts. The armature winding is Y-connected 

 and has an eft' Man-, of 0.081 ohm per phase. Thedata 



for the open-circuit characteristic and the full-load current satura- 

 tioii curve at zero power factor are: 



4 



