SINGLE-PHASE INDUCTION MOTOR

105

and assume, as the simplest ease, a resistance, a = 0.3, inserted
in series to the one motor circuit. That is:

Zi = 0,
Z2 = a.

(44)

It is then :

_ e<>

r + ja; ~ 0.1 + 0.3 j

,• _

/2 ~

r + a + jx ~ 0.4 + 0.3 j
= e0(1.6 - 1.2 j);

(33):

mv l?
(34). B^

e\ =
(35): w(c

/ = e0 (2.6 - 4.2 j),

i = 4.94'e0;

r + &

0.1 + 0.3 j

-_

= 0.632 e0;

= 0.52 + 0.36 3,
0.36

(38):
(43) :

sin $ = 0.57;
t = 0.36;
v = 0.46.

Thus this arrangement gives 46 per cent., or nearly half as
much starting torque per volt-ampere taken from the supply
circuit, as the motor would give as polyphase motor.
However, as polyphase motor with low-resistance secondary,
the starting torque per volt-ampere input is low.
With a high-resistance motor armature, which on polyphase
supply gives a good apparent starting-torque efficiency, v would
be much lower, due to the lower angle, <j>. In this case, however,
a reactance, +ja, would give fairly good starting-torque efficiency.
In the same manner the effect of reactance or capacity inserted
into one of the two motor coils can be calculated.
As instances are given, in Fig. 37, the apparent torque efficiency,
v, of the single-phase induction-motor starting device consisting
6f the insertion, in one of the two parallel motor circuits, of
various amounts of reactance, inductive or positive, and capacity