Ill

f

m

]|
r

i'j

I1!

100

ELECTRICAL APPARATUS

these voltages, ej; ea, eo, are reduced to the same number of turns
of the circuits, as customary.
If then:

Q = volt-amperes input of the single-phase

motor with starting device, and
Qo = volt-amperes input of the same motor
with polyphase supply,

. Q

is the volt-ampere ratio, and thus:

(22)

(23)

is the ratio of the apparent starting-torque efficiency of the
single-phase motor with starting device, to that of the same
motor as polyphase motor, v may thus be called the apparent
torque efficiency of the single-phase motor-starting device.

In the same manner the apparent power efficiency of the start-
ing device would result by using the power input instead of the
volt-ampere input.

65. With a starting device producing a quadrature voltage, er,

(24)

is the ratio of the quadrature voltage to the main voltage, and
also is the starting-torque ratio.
The quadrature flux:

er = tea

(25)

requires an exciting current, equal to t times that of the main
voltage in the motor without starting device, the exciting current
at standstill is: "

60 7' = -^

and in the motor with starting device giving voltage ratio, 2,
the total exciting current at standstill thus is:

(1 +1)