# Comparison between Induction Motor and Transformer

- Link: https://studyelectrical.com/2018/03/similarities-or-differences-between-induction-motor-and-transformer.html
- Published: 2018-03-01T13:31:00+00:00
- Author: 

An [induction motor](https://studyelectrical.com/2014/11/how-three-phase-induction-motor-work.html)
may be considered to be a transformer with a rotating short-circuited secondary.
The stator winding corresponds to the transformer primary and the rotor winding 
to the transformer secondary.
  However, the following differences between the two
are worth noting: ⌊1⌉

### 1. Air Gap

Unlike a transformer, the magnetic circuit of a 3-phase induction motor has an air
gap. Therefore, the magnetizing current in a [3-phase induction motor](https://studyelectrical.com/2014/11/how-three-phase-induction-motor-work.html)
is much larger than that of the transformer.
  For example, in an induction motor,
it may be as high as 30-50 % of rated current whereas it is only 1-5% of rated current
in a transformer.

### 2. Leakage Reactance

In an induction motor, there is an air gap and the stator and rotor windings are
distributed along the periphery of the air gap rather than concentrated on a core
as in a transformer.
  Therefore, the leakage reactances of stator and rotor windings
are quite large compared to that of a transformer.

### 3. Mechanical and Electrical Outputs

In an induction motor, the inputs to the stator and rotor are electrical but the
output from the rotor is mechanical. However, in a transformer, input, as well as
output, is electrical.

### 4. Slip

The main difference between the induction motor and transformer lies in the fact
that the rotor voltage and its frequency are both proportional to slip s.
  If f
is the stator frequency, E₂ is the per phase rotor e.m.f. at standstill and X₂ is
the standstill rotor reactance/phase, then at any slip s, these values are:  Rotor
e.m.f./phase, E₂’  = s E₂ Rotor reactance/phase, X₂’  = sX₂ Rotor frequency, f’ 
= sf

### Related posts:

No related posts.