Concept & Reasoning

Both transformers and induction motors operate by mutual induction. The stator winding produces an alternating/rotating magnetic field that induces rotor emf and current, just as transformer primary flux induces secondary emf. At standstill the analogy is especially direct; during rotation, rotor frequency becomes sf rather than supply frequency and the mechanical output introduces the slip-dependent equivalent resistance R2'/s. This transformer analogy is the foundation of the induction-motor equivalent circuit.

How to Solve It in the Exam

Induction motor = rotating transformer.

Important Exam Point

Use the transformer equivalent circuit first, then introduce slip.

Quick Trick

Induction motor = rotating transformer.

Common Mistake

Do not equate an induction motor to a synchronous motor; its torque requires slip.

Concept & Reasoning

Both transformers and induction motors operate by mutual induction. The stator winding produces an alternating/rotating magnetic field that induces rotor emf and current, just as transformer primary flux induces secondary emf. At standstill the analogy is especially direct; during rotation, rotor frequency becomes sf rather than supply frequency and the mechanical output introduces the slip-dependent equivalent resistance R2'/s. This transformer analogy is the foundation of the induction-motor equivalent circuit.

How to Solve It in the Exam

Induction motor = rotating transformer.

Important Exam Point

Use the transformer equivalent circuit first, then introduce slip.

Quick Trick

Induction motor = rotating transformer.

Common Mistake

Do not equate an induction motor to a synchronous motor; its torque requires slip.

Concept & Reasoning

Both transformers and induction motors operate by mutual induction. The stator winding produces an alternating/rotating magnetic field that induces rotor emf and current, just as transformer primary flux induces secondary emf. At standstill the analogy is especially direct; during rotation, rotor frequency becomes sf rather than supply frequency and the mechanical output introduces the slip-dependent equivalent resistance R2'/s. This transformer analogy is the foundation of the induction-motor equivalent circuit.

How to Solve It in the Exam

Induction motor = rotating transformer.

Important Exam Point

Use the transformer equivalent circuit first, then introduce slip.

Quick Trick

Induction motor = rotating transformer.

Common Mistake

Do not equate an induction motor to a synchronous motor; its torque requires slip.