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Dynamic Braking
Since the armature is still rotating in a magnetic field, it will continue
to generate a CEMF, which is proportional to the strength of the
magnetic field. The armature will also cause a current flow opposite
to that of the power supply to flow in the current limiting (braking)
resistor, which will in turn cause the motor to try and reverse itself.
In the process of trying to reverse itself, the speed will be rapidly
reduced from the original direction. As the speed decreases, so
does the CEMF.
When the motor reaches zero speed, the CEMF is also zero and
the motor has been dynamically braked to a stop. The speed of
braking is controlled by the braking (current limiting) resistor's
resistance. The lower the resistance, the greater the current flow.
And, since the reversing current or braking torque is proportional to
the current flow, the faster the stopping. For the SL10U a jumper
wire instead of a resistor gives optimum braking.
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