32 ALTERNATING GENERATORS AND SYNCHRONOUS MOTORS. 
60. Example. 2.—Determine the size of the prime mover and 
the rating of the generator, when as alternator it has to 
deliver 600 K.W. to a motor and lamp cireuit with a 
power factor of .8. 
Solution.—The rated capacity of the generator will be 
600 
3>= 750 KVA. 
If the efficiency on full inductive load is equal to 94%, then 
ty of the prime mover will he” aaa 
the capacity of the prime move wre ae 
860 HP. Ans. 
Supposing the generator has to supply a lighting cireuit, that 
is, a circuit without inductance. The power factor is then 
Se. Net ee 
Ed Zn s AGL. 
°, Z | 
OPEN WIWLING CLOSED WINDING. 
Fies. 17 AND 18.—ARMATURE CIRCUITS OF SINGLE-PHASE 
ALTERNATORS. 
cos. P = 1 and the rated capacity of the alternator will 
be 600 KVA. Ans. 
The horse power of the engine remains practically the same 
as before, because generally there is only a small difference 
between the efficiencies on inductive and non-inductive full 
loads. 
61. Voltage and Current of Single Phase Machines.— 
The normal working pressure between the mains and the | 
number and connections of the phases are the conditions 
next to be considered. 
In the case of a single phase cireuit, the line pressure FE is 
the same as the voltage generated in the armature winding, 
E,, provided that the alternator has an open winding, cor- 
Md g , i 
ee a Lr 
