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Plugging braking of induction motor is done by.
disconnecting the one phase from the source
disconnecting the All phases
by disconnecting the All phases from the line and connected it with DC Supply
reversing the phase sequence of the motor
reversing the phase sequence of the motor
Plugging (or reverse current braking) of an induction motor is achieved by reversing the phase sequence of the stator supply voltage. This causes the rotating magnetic field (RMF) to rotate in the direction opposite to the actual rotor rotation.
Plugging (or reverse current braking) of an induction motor is achieved by reversing the phase sequence of the stator supply voltage. This causes the rotating magnetic field (RMF) to rotate in the direction opposite to the actual rotor rotation.
spluggingтАЛ=NsтАЛтИТNsтАЛтИТNтАЛ=2тИТs тАФ Slip during plugging
TbrakingтАЛтИЭ(R2тА▓тАЛ)2+(sX2тА▓тАЛ)2sR2тА▓тАЛтАЛ тАФ Braking torque expression
When any two phase leads connected to the stator are interchanged, the direction of the rotating magnetic field instantly reverses. This causes the motor slip to become s=2тИТs0тАЛ, which is greater than 1, producing a powerful counter-torque that opposes the rotor's motion and rapidly brings the motor to a stop.
Interchanging any two supply terminals reverses the phase sequence.
The rotor slip during plugging ranges between 1 and 2.
Electrical energy is drawn from the supply and wasted as heat in the rotor resistance.
A mechanical or speed-sensing switch (zero-speed switch) is required to disconnect power when the motor stops, preventing reverse rotation.
Provides quick braking and high braking torque.
Simple control circuit implementation.
High energy loss dissipated entirely as heat in the rotor circuit.
Requires a zero-speed switch to disconnect power at zero speed.
Rolling mills, elevators, and cranes.
Machine tools requiring rapid stopping or quick reversal.
Option A (disconnecting one phase) causes single-phasing, which can overheat the motor.
Option B (disconnecting all phases) corresponds to coasting to a stop (coasting/free-wheel).
Option C (connecting DC supply after disconnecting AC supply) describes dynamic (rheostatic) braking, not plugging.
D is correct тАФ Plugging braking is executed by reversing the phase sequence of the motor's supply.
Always remember for exams: Plugging yields slip s>1 (s=2тИТsmotoringтАЛ), Dynamic braking operates with 0тЙдsтЙд1, and Regenerative braking operates with negative slip (s<0).