In electric braking of shunt motors, plugging is used to control.

1. Printing press

2. Rolling mills

3. Elevators

The incorrect amongst these is / are:

Plugging:

• In this method, the motor is reconnected to the supply in such a way that it has to develop torque in opposite direction to the movement of the rotor, it can be done by reversing the connections of the armature
• The motor will decelerate until the speed is zero and then accelerates in opposite direction; Immediately, it is necessary to disconnect the motor from the supply as soon as the system comes to rest
• The kinetic energy of the rotating parts of the motor is wasted and an additional amount of energy from the supply is required to develop the torque in the reverse direction, i.e. the motor should be connected to the supply during braking
• It can be applied to both DC and AC motors.
• During plugging the effective voltage across the armature will be (V + Eb) which is almost twice the supply voltage. The armature current is reversed, and high braking torque is produced.

The Plugging is commonly used for the following applications:

• Controlling elevators
• Rolling Mills
• Printing Presses
• Machine tools