**Contents**show

## Why the magnetizing current of an induction motor much higher than that of a transformer?

The magnetic circuit of the induction motor **has an air gap and hence higher reluctance** as compared to a transformer magnetic circuit having no air gap. In order to set up magnetic flux inside the air gap of induction motor, large magnetizing current is required.

## Why no load current in a transformer is very low?

In the case of no-load, the secondary terminal of the transformer is open. There is no path available for the current to flow on the secondary side. Hence, **the transformer does not draw current from the source**.

## Why the exciting current of induction motor is so high as compared to the power transformer?

Unlike that of a power transformer, **the magnetic circuit of the induction motor has an air-gap**. Therefore, the exciting current of induction motor (3O to 4O% of full-load current) is much higher than that of the power transformer.

## Why the PF of an induction motor is less than 0.5 on no load?

As the motor is running at no load, the total input power is equal to the constant iron loss, friction, and windage losses of the motor. Since the power factor of the induction motor under no-load condition is generally less than 0.5, thus the **Wattmeter** reading of one of the Wattmeter will show a negative reading.

## Why does induction motor has high starting current?

This high current in the rotor will **create its own magnetic field** which opposes the main stator magnetic field, this weakens the stator magnetic field so the back EMF in the stator will drop and the supply voltage will be much higher than the stator back EMF and so the supply current increases to a high value.

## Why magnetizing current of three phase induction motor is much more in magnitude than that of a three phase transformer of the same power rating?

(1) Unlike that of a transformer, the magnetic circuit of a 3-phase induction motor has an air-gap. **This increases the reluctance of the magnetic circuit of the motor** to a great extent. Consequently, the magnetizing current drawn by an induction motor is much more than that of a power transformer.

## What is the purpose of no load current in transformer?

Explanation: The no load current is **about 2-5% of the full load current and it accounts for the losses in a transformer**. These no-load losses include core(iron/fixed) losses, which contains eddy current losses & hysteresis losses and the copper(I2*R) losses due to the no Load current.

## Why is no load current of 3phase induction motor is quite high compared to transformer?

Explain why the no load current of an induction motor is much higher than that of an equivalent transformer. **loss, eddy current loss, friction and windage losses**. Hence the no load current of induction motor is higher. Starting torque increases with increase in value of rotor resistance.

## Why motor takes more current?

Probable causes of high current with load include mechanical overload, **excessively high magnetic flux densities** and, less frequently, an open rotor. An error in winding data that results in lower-than-design-level magnetic flux also can cause high current with load.

## What should be the no load current of an induction motor?

Star Connected motor:

The motor will take 10% of the full load current. therefore, No load current at star connection = **0.1 x Motor Full load current**.