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How we can change the direction of rotation in a split-phase single phase induction motor?
by interchanging Running winding terminal
by interchanging Starting winding terminal
by interchanging Both (Starting & Running) winding terminal
by interchanging either Starting or Running winding terminal
by interchanging either Starting or Running winding terminal
Quick Trick: Remember that reversing ONE winding (Starting OR Running) reverses the phase difference and flips motor direction. Reversing BOTH restores the original relative phase, keeping the direction unchanged.
Remember that reversing ONE winding (Starting OR Running) reverses the phase difference and flips motor direction. Reversing BOTH restores the original relative phase, keeping the direction unchanged.
Understand the Principle of Rotation
In a split-phase single-phase induction motor, direction of rotation depends on the phase angle difference between the current in the starting (auxiliary) winding and running (main) winding.
Analyze the Effect of Terminal Reversal
Reversing current flow in ONE winding reverses its magnetic field direction, flipping the phase relationship and changing motor rotation (e.g., from clockwise to counter-clockwise).
Evaluate the Double Reversal Case
Interchanging terminals of BOTH windings simultaneously reverses both magnetic fields, which cancels out the relative phase change and keeps the rotation direction the same.
A: Incomplete because interchanging starting winding terminals works as well. B: Incomplete because interchanging running winding terminals works as well. C: Incorrect because interchanging both keeps the relative phase relationship unchanged, maintaining the same direction.
D is correct because interchanging the terminals of either the starting winding or the running winding alone flips the relative magnetic field phase angle, reversing the direction of rotation.
Common trap: Students often choose 'interchanging both terminals' assuming more changes produce the desired effect, but double reversal cancels the shift out.