402

ELECTRICAL APPARATUS

i!

'I

Main E.m.f. of Rotation:

W = _J^£__{jLziA4

*^ 1 1 •— C0X4 ICQ — j'S

approximately:

a -

' (1 - c0X4) (c« - JS)
Quadrature E.m.f. of Rotation:

E'* = +jSte.

Power Output:

P=Pi + 1\

= [#'!,/,]' 4- [#%
Power Input:

P» = K /il1 + (e», /
Volt-ampere Input:

P — dii + 62^2

(95)

(96)

(98)

where the small letters, /i and ?*2, denote the nhsoluto values of
the currents, /i and 72.
When z*i and is are derived from the same compensator or
transformer (or are in shunt with each other, as branches of the
same circuit, if e\ = €2), as usually the case, in the primary cir-
cuit the current corresponds not to the sum, {(1 — t) z'j, + ti^\ of
the secondary currents, but to their resultant, [(1 — t) Ji .+ tl»]1,
and if the currents, /i and J2, are out of phase with each other,
as is more or less the case, the absolute value of their resultant
is less than the sum of the absolute values of the components.
The volt-ampere input, reduced to the primary source of power,
then is:
PaQ = e[(l -Oh + tfd1, (99)
and:
P < P
ao a*
P
From these equations then follows the torque: D = -$-. the
A3
P
power-factor, p = 5-^, etc.
2 aQ
These equations (90) to (99) contain two terms, one with, and
one without t == —, and so, for the purpose of investigating the
6