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A pony motor is basically
Small induction motor
Series motor
Shunt motor
Double winding A.C/D.C motor
Small induction motor
A pony motor is a small induction motor used as an auxiliary starting device to bring a synchronous motor up to its synchronous speed. Once the synchronous motor reaches synchronous speed and is synchronized with the AC supply, the pony motor is mechanically disconnected or de-energized.
A pony motor is a small induction motor used as an auxiliary starting device to bring a synchronous motor up to its synchronous speed. Once the synchronous motor reaches synchronous speed and is synchronized with the AC supply, the pony motor is mechanically disconnected or de-energized.
NsтАЛ=P120fтАЛ тАФ synchronous speed where NsтАЛ is speed in rpm, f is frequency, and P is number of poles.
Synchronous motors are not self-starting due to the inertia of the rotor not being able to follow the rapidly reversing stator magnetic field. The pony motor provides the necessary torque to accelerate the rotor to near-synchronous speed, allowing the electromagnetic locking between the stator field and rotor poles to occur.
Pony motors are generally rated for a fraction of the synchronous motor's power.
They provide the starting torque required to overcome inertia and friction.
The process involves starting the induction motor first, then syncing the main motor.
Simple and rugged construction
Reliable starting method for large synchronous motors
Requires additional space and maintenance
Increases the overall cost of the motor installation
Large industrial synchronous motors
Motor-generator sets
Pony motors are often required for large synchronous machines where Damper windings are insufficient or not provided.
Option B (series motor) and C (shunt motor) are DC machines and are unsuitable for this specific AC startup application.
A is correct тАФ A pony motor is a small induction motor used as an auxiliary prime mover to bring a synchronous motor up to its rated synchronous speed.
Always remember that synchronous motors are not inherently self-starting; they require either damper windings, a pony motor, or variable frequency drive (VFD) for startup.