208

ELECTRICAL APPARATUS

The current in the rotor circuit, in which the direction of
rotation is opposite, or ahead of the revolving field, then is,
when neglecting the exciter current:

1 2 = i + jii.

(If Y = exciting admittance, the exciting current is Jo = EY,
and the total rotor current then 7o + /a.)
Then in the rotor circuit:

E = jB0 + (Z0 + Z«)
and in the stator circuit :

E = Ei + ZJi.
Hence :

Ei = Eo + I2 (Z0 + Z2)

or, substituting for Jj. and /2:

Ex = Eo + i (ZQ + Zz- Zi) + jii
Denoting now :

(1)
(2)
(3)

Za). (4)

and substituting:

or, since EI = e\:

l = E,

or the absolute value:

Hence:

ii)2 + («4i + rail)2.

r4i

(7)
(8)

(9)

That is, the terminal voltage, ei, decreases due to the decrease
of the square root, but may increase due to the second term.
At no-load:
i = 0, i\ = 0 and e\ = 60.