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Figure 9.8 AC series motor or universal motor
Since I is proportional to load on the motor, we can say I α load.
a
a
Using the relation in (i) and (iii) above, we can draw the characteristics
such as torque versus load, speed versus load, and torque versus speed as
shown in Fig. 9.9.
2
is the equation of a parabola of the form y = x . is the equation
of a rectangular hyperbola of the form These are shown in
Figs. 9.9 (a) and (b), respectively. From the relationship of T versus I and N
a
versus I , the relationship between T versus N can be developed as has been
a
shown in Fig. 9.9 (c).
9.8 OPERATION OF A SERIES MOTOR ON DC AND AC (UNIVERSAL MOTORS)
