Induction Motor as Transformer

It will not be wrong to say that induction motor is an essential transformer where the stator forms the primary and rotor forms the short circuited rotating secondary. How is it possible?

It is possible because of the transfer of the stator to the rotor. This takes place in the induction motor with the help of flux which links the two on mutual basis.

Fig. 20.Induction motor as transformer.

The vector diagram (Fig. 21) is similar to that of a transformer.

V1 = E1 + I1 (R1 + jX1)

Er = 12 (R2 + jsX2)

Though an induction motor might act as a transformer, but still are different from each other. Following are few points illustrating the difference between the two:

  • The magnetic leakage and leakage reactance of rotor: Higher in an induction motor than a transformer
  • Magnetizing current: higher in the induction motor than the transformer because of the sir gap in the magnetic circuit.
  • Ratio of stator and rotor currents and turns per phase in the rotor: equal in the transformer and not in induction motor
  • Efficiency: Efficiency is lower in the induction motor than transformer because of higher losses at the induction end.

Fig. 21.Vector diagram of induction motor.

18.1. Rotor output

Talking about the primary current I1, it consists of two parts:

  • I0
  • I2

which is later transferred into the rotor where I0 is used to meet the copper and the iron is lost in the stator itself.

Talking about the primary voltage V1, some of the same is absorbed at the primary stage with remaining E1 transferring into the rotor.

If the angle between E2 and I2’ is Φ


Rotor input/phase = E1H1’ cos Φ

Total rotor Input = 3E1I2’ cos Φ

The electrical input to the rotor wasted in the form of the heat

= 3I2Ercos Φ (or 3I22 R2)

I2’ = KI2 or I2 = I2’/ K

Er = sE2 and E2 = KE1

Er = sKE1

18.2. Equivalent circuit of the motor

When the motor is loaded, the rotor current I2 is given by:

The formula illustrates that the rotor circuit consisting of the fixed resistance R2 along with the variable reactance sX2 connected across E; = sE2 is equivalent to the rotor circuit with fixed reactance X2 which is connected in the series along with variable resistance R2/S and supplied with constant voltage E2 is sown in the figure.

In additon to the same, the resistance R2/s can also be illustrated as:

The formula consists of the two points:

  1. R2 represents the rotor copper less as the rotor resistance
  2. The second part is R2 (1/s – 1) which is knows as load resistance RL.

RL is equivalent to mechanical load on the motor. We can also say that mechanical load is represented by non-inductive resistance [R2 (1/s-1)]

Links of Previous Main Topic:-

Links of Next Electrical Engineering Topics:-


We’re rated Excellent

4.7 out of 5 based on 39 reviews

Order Homework Help
Click or drag files to this area to upload. You can upload up to 5 files.
We do not share numbers with 3rd party.

Join over 200,000+ happy students served our tutors

Take a look at independent reviews to see what users have to say about our homework help service.


overall rating
on LiveChat


of users
recommend service

How It Works

1. Get Price Estimate.
1. Get Price Estimate.


Send us your homework. Mention deadline & upload relevant files.

2. Pay Securely.
2. Pay Securely.


We accept all major credit cards. Partial payments also accepted.

3. Get Solutions.
3. Get Solutions.


Receive error-free, step-by-step solutions in your email.


Why use Myhomeworkhelp?

We provide you with the homework help from top experienced experts. Your satisfaction is a priority to us. Get better grades or money-back. It’s that risk-free! Furthermore, everything about you is kept confidential.

How quickly can you help me with my homework?

We take pride in our 24×7 homework help services. Which means, student can approach us anytime, to get help even on short notices. As short as few hours! And yes, we provide complementary plagiarism-free report.

How much will it cost?

We do not have a monthly fees or minimum payments. Each homework task is quoted a unique price. It is based on tutor’s estimate of the time it will take them to complete your task. There are no obligations, and you are free to discuss the price quote with the tutor.
We do accept partial payment (subject to our policy) to start working on your assignment help. You can pay the remaining amount when your task gets completed. No pressure of up-front payment. No hidden costs.

Who are your tutors?

All our experts are highly qualified professionals – holding at least Master’s degree of their respective fields of expertise. We are very selective and choose only the best qualified tutors for each academic subject. All tutor applicants must provide academic transcripts for each degree they hold, and are tested and screened carefully by our staff.

I have privacy concerns. Can I trust you?

Myhomeworkhelp has completed over 250,000 homework help tasks over the last 12 years. But do not take our word for it! See our here and on Trustpilot. Furthermore, everything about you is kept confidential. Your credit card information is not stored anywhere, and use of PayPal relies on their secure payment networks. Your identity, payment and homework help are in safe hands.

Check our video

Our Reviews