What is Induction Motor? Important questions related to it
In this post, we will talk about several main questions related to Induction Motor. Like what is an induction motor, how and on what principle does this motor work? And at the same time, we will talk about several important interview questions related to Induction Motor.
Induction motor design
If we first talk about the design of the induction motor, it is the same as all other motors. The design of the induction motor is quite easy and strong.
In all induction motors, we see two main parts.
- Stator
- Rotor
Induction-motor-stator-and-rotor
Stator
 |
| Induction-motor-stator |
The part of the motor which is completely stationary is called the stator. The outer shell of the stator is called the stator frame and yoke. And talk about the part inside the Stater. So many slots are made in it, on which three-phase winding is done.
This winding is made of copper or aluminum wire. This winding is placed inside the slot in the stator in such a way that when we provide a 3 phase electrical supply to the winding of this motor, the rotating magnetic field around the winding means the rotating magnetic field.
Rotor
 |
| Induction-motor-rotor |
All of us come to know by the name of the rotor that this is the rotating part in the motor. The texture of the rotor is very simple. To make this, a shaft is first taken, which is like the cylinder shape. Squirrel-cage-rotor-construction next, we place the conductor bar inside this cylindrical core shaft. We get to see this conductor bar of copper or aluminum only.
After the conductor bars are kept of the cylinder core, their ends are shortened with the help of the end ring. The reason behind shorting these conductor bars is to create a close coil above the rotor.
What is an Induction motor?
An induction motor or asynchronous motor is an AC electric motor in which the electrical energy in the rotor needed to produce torque is obtained by electromagnetic input from the magnetic force of the stator. The motor which follows the law of electromagnetic induction to complete its work is called an induction motor.
Now the next question that will be coming to the mind of all of you is, what is this electromagnetic induction?
Electromagnetic induction law - This rule tells us one main thing, that if we link a magnetic field and a close coil, then an EMF will be created in our close coil.
Now finally we know how this rule works and how induction motor works.
Three Phase Induction Motor Working principle
When we provide an electrical supply in the three-phase induction motor, it causes the current to flow in the winding of the motor. And the current flowing through it creates a rotating magnetic field near the motor winding.
Induction motor magnetic field
This rotating magnetic field goes and links with the rotor. After this, Michael Faraday's law of electromagnetic induction interrupts. This rule tells us that whenever the magnetic field is linked in a closed circuit, EMF is generated on the conductor of that circuit.
If we see this rule in the condition of the motor, it means this. As soon as the magnetic field from the winding of the motor links to the rotor, then an EMF will be generated on the conductor bar on our rotor. And current will start flowing through the conductor bar of the rotor.
Now after all this, when the current flows in the conductor bar of the rotor, then that current will also generate a magnetic field near itself. And this magnetic field produced by the rotor will create a force on the rotor and the rotor will start rotating.
Also, read- Differences between AC motor and DC motor.
Induction Motor Interview Question
Interview questions related to induction motor
Q 1. What is an Induction motor?
Ans- The motor which accomplishes its task with the help of electromagnetic induction is called an induction motor.
Q 2. Types of Induction Motor?
Ans - Induction motors are mainly of two types.
- Squirrel cage Induction motor
- Slip ring induction motor
Q 3. The use of induction motor is called?
Ans- Induction motor is the most commonly used motor among all electrical motors. If you have seen the motor in the water motor company of your house, then it is all induction motor.
If we see all used AC motors have AC induction motor up to 90-95%.
Q 4. The induction motor and Asynchronous motor are same?
Ans- Both these motors are the same.
Asynchronous motor is known to us mostly by the name of induction motor, it is two names of the same motor.
Q 5. Is there also a DC induction motor?
Ans- No induction motor is a type of AC motor.
There are mainly 2 types of AC motors.
1. Synchronous motor
2. Asynchronous motor (induction motor)
Q6.What is the principle of induction motor?
Ans-The motor which works on the principle of electromagnetic induction is known as the induction motor. Electromagnetic induction is the phenomenon in which the electromotive force induces across the electrical conductor when it is placed in a rotating magnetic field.
Q7.Why induction motors are better?
Ans-The motor shaft rotates. Induction Motors induce the magnetic field within the rotor by implanting a short currently in the squirrel cage. This concept affects higher losses in the rotor and causes higher heat and less efficiency. Higher efficiency motors use copper because of their better electromagnetic behavior.
Q8.How does the induction motor starts?
Ans- A 3-phase Induction Motor is Self Starting. When the supply is connected to the stator of a 3-phase induction motor, a rotating magnetic field is produced, and the rotor begins rotating and the induction motor starts.
Q9.What are the types of induction motors?
Ans- Single-Phase Induction Motors-Split Phase Induction Motors. 2&3. Capacitor Start and Capacitor Start Capacitor Run Induction Motors. Shaded Pole Induction Motors.
3-Phase Induction Motors are Squirrel Cage Induction Motor, Slip-ring, or Wound Rotor Induction Motor.
Q10.What are the uses of induction motors?
Ans- AC induction motors are the most commonly electric motors in the world. These simple, reliable, and economical motors are found in refrigerators, washing machines, and as well as on conveyors, pumps, winders, wind tunnels, and other industrial equipment.
Q11.What is the main disadvantage of induction motors?
Ans- A single-phase induction motor, unlike a 3-phase induction motor, does not have a self-starting torque. Auxiliaries are required to start a single-phase motor. During light load conditions, the power factor of the motor drops to a very low value.
Q12.What is the difference between an induction motor and a Synchronous motor?
Ans- Difference between 3-Phase Induction Motor and Synchronous Motor. The stator winding of the Induction Motor is energized from an AC source.
Synchronous Motor always runs at synchronous speed, and the speed of the motor is independent of load, but an induction motor always runs less than the synchronous speed.
Q13.What are the main parts of an induction motor?
Ans- A 3-phase Induction motor mainly consists of two parts called the Stator and the Rotor. The stator is the stationary part of the induction motor, and the rotor is the rotating part.
Q14.Which motor used in the lift?
An AC slip ring or DC compound motors are preferred for lifts. Shunt-type commutator motors are preferred in the case of single-phase installation. The latest lift designs use 3-phase induction motors with variable frequency drive electronic controls.
Q15.What happens when the induction motor is loaded?
Ans- As the load on the induction motor is increased the current will also increase to deliver the demanded power. The slip of the motor will increase with an increase of loading on the motor, and finally, the speed of the motor will decrease accordingly.
Q16.What means no-load test of induction motor?
Ans-The no-load test of an induction motor is the same as the open-circuit test of a transformer. The motor is not connected to its load, and the rated voltage at the rated frequency is applied to the stator to run the motor without a load.
Q17.What is the difference between Squirrel Cage Induction motor and slip ring motor?
Ans- The key main differences between Slip Ring & Squirrel Cage Induction Motor. The motor whose rotor is wound type such type of motor is called slip ring induction motor, whereas the squirrel cage motor, has a squirrel cage type rotor. The starting torque of the slip-ring motor is high, whereas in the squirrel cage motor it is low.
Q18.Why the synchronous motor is not self-starting?
Ans- The synchronous motors are not self-starting because this property is due to the inertia of the rotor, it cannot instantly follow the rotation of the magnetic field of the stator. Once the rotor nears the synchronous speed, the field winding is excited, and the motor pulls into synchronization.
Q19.Is single phase motor self-starting?
Ans- Single-phase induction motors are not self-starting without an auxiliary stator winding driven by an out-of-phase current of near 90°. Once started the auxiliary winding is optional. The auxiliary winding of a permanent split capacitor motor has a capacitor in series with it during starting and running.
So, Hope you must have got answers to many questions related to your Why we use Strips on AC Motor today.
Any Questions related to this topic please feel free to ask me on my other social media accounts.
Thank You!
Happy Learning!
