Page 629 - Basic Electrical Engineering
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or,
Torque, T = KϕI (7.4)
a
where
Thus, we can say that torque developed is proportional to the magnetic
field strength or the magnetic flux ϕ and the magnitude of current I flowing
a
through the conductors placed in the magnetic field.
7.9 STARTING A DC MOTOR
For a dc motor we can express armature current as (see eq. 7.3)
where R is the armature winding resistance and E is the back EMF or
a
b
induced EMF in the armature.
At the moment of start, the speed N of the motor is zero. If N = 0, E = 0.
b
Thus,
