SINGLE-PHASE INDUCTION MOTOR 121

The condenser motor is discussed on page 249 of " Theory and
Calculation of Alternating-current Phenomena." •

(c) The condenser-inductance monocyclic starting device.
By suitable values of capacity and inductance, a balanced three-
phase triangle can be produced, and thereby a starting torque
equal to that of the motor on three-phase voltage supply, with
an apparent starting-torque efficiency superior to that of the
three-phase motor.

Assuming thus:

Yi = +jbi = capacity, 1 ,

Yz = — jb% = inductance, j ^ *

If the voltage triangle, e, $i, $2, is a balanced three-phase tri-
angle, it is:

P

2e J (92)

{Substituting (91) and (92) into (83), and expanding gives:
(&, - &! + 2 6) \/3 - j (62 + 61 - 2 g V3) = 0;

thus:

62 - bi + 2 b = 0,
62 + bi - 2{7\/3 = 0;
hence:

(93)

thus, if:

b > g V~3,

the second reactance, Z2, must be a capacity also; if

only the first reactance, Zi, is a capacity, but the second is an
inductance.
78- Considering, as an instance, a low-resistance motor, and a
high-resistance motor:
(a) (b)
7 = 9 - jb = 1 - 3 j, Y = g-jb = 3-j,