INDUCTION-MOTOR REGULATION

125

and the voltage at the motor terminals is:

/ o- z°

If e0 is the voltage required at the motor terminals at full-load,
and ^'0° the current, Zi° the total impedance at full-load, it is:

<•*""•* ^

SP
00
1000 6000 5000 4000 3000 2000 1000

Y -0.01- 0.1 j Z=0.1+0.3j TRANSFORMER IMPEDANCE I cf 0.04+ 0.08 j CONSTANT PRIMARY POTENTIAL 114.1 VOLTS

/

';

------

/

J Lj AMP.VOLTS = p PERCENT

_,

E.
VI. F.
T MO
TOR T

AL8

A

^

y-
*• -------- ,
------- —
•=: — .

SPEE
D

-~ -
— — — .
J

90

,
/

>
^
80

/

/

70

&
/

/

RO

--------
--------
-<<
f/

^
X

50

/
—

40

"7
— . ^
ZL.
X

80

^

?0

-*~-
^
^

10

/
1C
00
20
00
3C
00 1 40
OUTPUT
)0 1 50i
K)
G(
00

0

FIG. 43. — Induction-motor load curves corresponding to 110 volts at motor
terminals at 5000 watts load.

hence, the required constant supply voltage is:

and the speed and torque curves of the motor under this condi-
tion then are derived from those at constant supply voltage, eu?
by multiplying all voltages and currents by the factor — > that
is, by the ratio of the actual terminal voltage to the full-load
terminal voltage, and the torque and power by multiplying with