SPEED CONTROL

17

Let, in an induction motor:

y0 = g — jb = primary exciting admittance;

ZQ = TO + JXQ = primary self-inductive impedance;

Zi — TI + jxi = internal self-inductive impedance, at full

frequency;

and let the condenser, C, be inserted into the secondary circuit.
The capacity reactance of C is

1

fc -

271-7(7

(1)

k

at full frequency, and - at the frequency of slip, 5.
s

The total secondary impedance, at slip, s, thus is:

k\

i* = ri + j (W - -)

and the secondary current:
sE

se

(2)

(3)

where:

= E Oi —

m

*

(4)

The further calculation of the condenser motor, then, is the
same as that of the standard motor.1
12. Neglecting the exciting current:

7oo = EY
the primary current equals the secondary current:

and the primary impressed voltage thus is:

1 " Theoretical Elements of Electrical Engineering," 4th edition, p. 318.
2