# Questions & Answers of Operating Principle of Single Phase Induction Motors

## Weightage of Operating Principle of Single Phase Induction Motors

Total 8 Questions have been asked from Operating Principle of Single Phase Induction Motors topic of Electrical Machines subject in previous GATE papers. Average marks 1.75.

The equivalent circuit of a single phase induction motor is shown in the figure, where the parameters are and $s$ is the slip. At no-load, the motor speed can be approximated to be the synchronous speed. The no-load lagging power factor of the motor is___________ (up to 3 decimal places).

A 375 W, 230 V, 50 Hz, capacitor start single-phase indication motor has the following constants for the main and auxiliary windings (at starting): $Z_m=(12.50+j15.75)\Omega$(main windings), $Z_\alpha=(24.50+j12.75)\Omega$ (auxiliary winding). Neglecting the magnetizing branch, the value of the capacitance (in µF) to be added in series with the auxiliary winding to obtain maximum torque at starting is ____________.

The direction of rotation of a single-phase capacitor run induction motor is reversed by

The flux linkage $\left(\lambda \right)$ and current $\left(i\right)$ relation for an electromagnetic system is $\style{font-family:Arial}{\lambda=\left(\sqrt i\right)/\mathrm g}$. When $i=2A$ and $g$ (air-gap length) $=10\;cm$, the magnitude of mechanical force on the moving part, in $N$, is ________.

A 220V, 50Hz, single-phase induction motor has the following connection diagram and winding orientations shown. MM' is the axis of the main stator winding (M1M2) and AA' is that of the auxiliary winding (A1A2). Directions of the winding axes indicate direction of flux when currents in the windings are in the directions shown. Parameters of each winding are indicated. When switch S is closed, the motor

In a stepper motor, the detent torque means