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# Induction Motor

## Starting Methods of Three Phase Induction Motor

Three-phase Induction motors draw six or more times rated current when started at rated voltage. Such high currents may pose serious problems for the motor and the electrical system when large motors are started. One way to reduce the starting current is to start the motor at reduced voltage. After …

## Three Phase Induction Motor Performance

Using the equivalent circuit of the three-phase induction motor and some additional information about the mechanical and core loses, one could calculate the performance of the three-phase induction motor from no-load to full-load. Figure 1 shows a set of generic curves of efficiency, current, power factor, and slip for an …

## Torque Speed Characteristics of Induction Motor

Figure 1 showed a plot of induction motor torque vs speed from zero to synchronous speed. This curve is called the torque-speed characteristic curve. We can derive an equation from the equivalent circuit that allows the calculation of the torque for a given value of slip. FIGURE 1    Induction motor …

## Three-Phase Induction Motor Efficiency

The equivalent circuit of the induction motor can be used to examine the losses and the efficiency of the machine. Efficiency is defined for an induction motor the same way as it is for any device: $\begin{matrix} \eta =\frac{Power\text{ }Out}{Power\text{ }In}=\frac{{{P}_{out}}}{{{P}_{in}}} & {} & \left( 1 \right) \\\end{matrix}$ Defining the …

## Three Phase Induction Motor Equivalent Circuit

The three-phase induction motor operates in some ways like a transformer. In the transformer, AC voltage is applied to the primary, which creates AC flux in the core. That flux links the secondary and induces a voltage of the same frequency, but with a voltage that depends on the transformer …

## Three Phase Induction Motor Working Principle

The three-phase induction motor, like all electric motors, operates by means of interaction between magnetic fields. The stator magnetic field in a three-phase induction motor rotates around the air gap between the stator and the rotor. The direction of field rotation determines which way the motor turns and is controlled …