ALTERNATING GENERATORS: AND. SYNCHRONOUS. MOTORS. 3D% 
The output of a three phase machine. with the star con- 
» nected armature, 
— 1,000 x KVA. = 3E, C, = 1.73 F, oa ae ees (dD) 
and with the delta connected armature 
SN ee A, oo i Cp aah. 10 15) Cy. as. - ss (6) 
64. Example 3.—Find the phase voltage and the armature 
eurrent of a 100 AVA. generator, when working as (1) 
a single phase, (2) as a two phase, or (3) as a three 
_ phase alternator, with a line voltage of 400 volts. 
65. Solution.—Referring to Par. 61, it is found, that for a 
single phase generator with an open armature winding, 
the phase voltage Ey, is equal to the line voltage £,, which 
in this case is 400 volts; and the armature current C, is 
equal to the line current Cj, which in this case is 200. 
- amperes. 
Substituting these values in equation (1), we have 
400 X 250 = 400 X 250 = 100,000 VA = 100 KVA., 
then the phase voltage E, = 400 volts, and the armature 
eurrent C, = 250 amperes. Ans. 
‘If a closed armature winding is used, from Equation (2) 
we have 2E, C, = E, C; = 1,000 X KVA., where each sec- 
; aan : C 
tion of the winding will carry a current equal to —, 
5 
therefore, ei = = = 125 amperes; whence, 
2 x 400 X 125 = 400 x 250 = 100 AVA. 
In this case the phase voltage LE, — 400 volts 
and the current per section C,—125 amperes. Ans. 
Two Phase Generator: In the case of a two phase generator 
with an open armature winding, we have from Equation 
c (3), i + 
2E, Cy. = 2E, C,; = 1,000 x KVA., 
which in the present ease is equal to 2 x 400 x 125— 
