76

ELECTRICAL APPARATUS

With the same rotor diameter of the induction machine, the
pole pitch would be increased inverse proportional to the number
of poles, and the exciting susceptance decreased with the square
thereof, thus giving the constants:

YQ = g -jb =0.02 -0.54J;
ZQ = r0+jxQ = 0.1 + 0.3.?;
Z1 = n +3x1 = 0.1 + 0.3;.

Assuming as synchronous motor synchronous impedance,
reduced to full frequency:

Z2 = r,+ jx2 = 0.02 + 0.2 j
this gives, for s = 0.05:

Z« = (n + r2) + ja (xl + x,) = 0.12 + 0.025 j,

and:

and from (14):

Z'. = r' + jx' =— = 2.4 + 0.5 j,

o

Z = r+jx = 0.84 + 1.4 j,

E =

1.32 - 1.29 f

v 1.84
thus:

3T9 = ^50° "" °-84{/0 "" L4*"<>)2 + (L4i/o ~~ 0.84 ^'0)2, (28)
and the power output :

p = //0(0.836 + 0.048 j) - (10 - 270 j),

(508 - 32 j) - /0 (0.241 + 0.326 j) A (29)

51. Fig. 29 shows the load curves of the concatenated couple,
under the condition that the synchronous-motor excitation and
thus its nominal induced voltage, 62, is varied so as to maintain
unity power-factor at all loads, that is:

*'"o = 0;
this gives from equation (28):

62*
3.39

= (500 - 0.84^0)2 + 1.96 iV,