What is magnetising current in induction motor?

Last Update: April 20, 2022

This is a question our experts keep getting from time to time. Now, we have got the complete detailed explanation and answer for everyone, who is interested!

Asked by: Dr. Brando Luettgen
Score: 5/5 (25 votes)

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.

What is magnetizing current?

Magnetization current can be defined as “the portion of the no-load current that is used to establish flux in the core of a transformer“. ... Generally, when a transformer is energized under no-load conditions, it draws a small amount of current.

What is Magnetising reactance in induction motor?

The magnetizing reactance X0 in an induction motor will have a much smaller value. In a transformer, I0 is about 2 to 5% of the rated current while in an induction motor it is approximately 25 to 40% of the rated current depending upon the size of the motor.

What is the importance of magnetizing current in machine design?

Magnetizing current and power factor being very important parameters in deciding the performance of induction motors, the induction motors are designed for optimum value of air gap or minimum air gap possible. Hence in designing the length of the air gap following empirical formula is employed.

What is the relation between the magnetizing current and power factor?

What is the relation between the magnetizing current and power factor? Explanation: Magnetizing current is indirectly proportional to the power factor. As the magnetizing current is large, the power factor is poor.

Magnetisation Current for Induction Motor

21 related questions found

What is the no load current percent of the full load current for the output of 0.75 kW?

Explanation: For output of 0.75 kW, the no load current is 50% of full load current.

What are the losses of induction motor?

The following are the losses in an induction motor:
  • Core loss in the stator and the rotor.
  • Stator and rotor copper losses.
  • Friction and windage loss.

What are the advantages of stepped cores?

reluctance of core. As the ratings are increased stepped or multi-stepped cores are preferred, which improve mechanical stability, reduce the length of mean turn and result in copper savings besides increasing efficiency and improving regulation.

What is the value of air gap of induction motor?

The number of slots/pole/phase should not be less than 2 otherwise the leakage reactance becomes high. The number of slots should be selected to give an integral number of slots per pole per phase. The stator slot pitch at the air gap surface should be between 1.5 to 2.5 cm.

What factors does the value of magnetizing current depends on?

How many factors does the value of the magnetizing current depends upon? Explanation: There are 3 factors upon which the magnetizing current depends upon. They are total mmf required, number of turns in the exciting winding and upon the way in which the winding is distributed.

What is no load test of induction motor?

The no-load test of an induction motor is similar to the open-circuit test of a transformer. The motor is not connected from its load, and the rated voltage at the rated frequency is applied to the stator to run the motor without a load. The 2-wattmeter method measures the input power of the system.

What is the working principle of induction motor?

Working Principle of Induction Motor

The motor which works on the principle of electromagnetic induction is known as the induction motor. The electromagnetic induction is the phenomenon in which the electromotive force induces across the electrical conductor when it is placed in a rotating magnetic field.

What is the difference between induction motor and transformer?

A transformer transfers electrical power from one circuit to another without changing the supply frequency, i.e. it only step-up or step-down the level of voltage and current, whereas induction motor converts electrical power into mechanical power.

What is the exciting current?

Excitation current is the current flowing into the high voltage winding with the low voltage side open. This current should be proportional to the No-load acceptance test but with the difference resultant from the use of test voltages different from nominal values.

Why do we test magnetizing current in transformer?

Magnetizing Current test on transformer is performed to locate defects in the magnetic core structure, shifting of windings, failure in between turn insulation or problem in tap changers.

What are bound currents?

Bound surface currents, the magnetic field, and magnetization inside a circular solenoid filled with a paramagnet. ... When the solenoid is filled with a paramagnetic or diamagnetic material, the magnetic field inside becomes B=B0+B′, where B′ is due to the surface current Kb resulting from the magnetization.

What happens when air gap is increase in induction motor?

If the air gap of an induction motor increases, 1) The permeability of the magnetic circuit rotor-to-stator will decrease. 2) The magnetizing inductance of the motor thus decreases. 3) The magnetizing current will increase; This will cause a poor power factor at all loads.

What are types of induction motor?

There are three basic types of small induction motors: split-phase single-phase, shaded-pole single-phase, and polyphase. In two-pole single-phase motors, the torque goes to zero at 100% slip (zero speed), so these require alterations to the stator such as shaded-poles to provide starting torque.

Which is not loss in transformer?

What are No-Load Losses (Excitation Losses)? It is the loss in a transformer that is excited at rated voltage and frequency, but without a load connected to the secondary. No-load losses include core loss, dielectric loss, and copper loss in the winding due to exciting current.

What is the square and stepped cores used?

9. When is square and stepped cores used? Explanation: Circular coils are required for high voltage distribution and power transformer. When circular coils are required square and stepped cores are used.

Why ferrite core is used in radio receivers?

In the coil, a low-loss, high-magnetic-permeability ferrite core is used that is stable against thermal fluctuation. The system can receive weak radio waves and can be used for several years without battery replacement because a small but high-performance ferrite core is used.

What are the 2 main types of losses in a motor?

There are two main kinds of losses in electric motors, which are often referred to as iron losses and copper losses. Dealing first with iron losses, these are made up of two 'components', namely eddy current losses and hysteresis losses.

What are the applications of induction motor?

The rotor of an induction motor can be a squirrel cage rotor or wound type rotor. Used in different applications, induction motors are also called Asynchronous Motors.
Some of the applications are mentioned below:
  • Pumps.
  • Compressors.
  • Small fans.
  • Mixers.
  • Toys.
  • High speed vacuum cleaners.
  • Electric shavers.
  • Drilling machines.

What is 3phase induction motor?

Three Phase AC Induction Motor. The three-phase AC induction motor is a rotating electric machine that is designed to operate on a three-phase supply. This 3 phase motor is also called as an asynchronous motor. ... The principle of operation of this motor is based on the production of a rotating magnetic field.