What is a Stator : Construction, Working and Its Uses

We know that there are different kinds of motors available in the market which is used in different applications based on its function. Day by day, the performance of these can also be increased due to the materials used in these types of motors. The materials used in all the motors are not the same but change depending on its type. But the motor performance can be improved by the optimization methods of the stator as well as a rotor. In electrical machines like motors and generators, the stator is the most important part. The current flow can be supplied from the rotating part of the system. This article discusses an overview of a stator and its working.

What is Stator?

Definition: A motor that has a stationary part is known as stator with a number of windings. Once an AC is applied to it, the polarity of the stator will automatically change constantly. Whenever the supply is given to this, then an alternating current will be supplied throughout the windings to generate an electromagnetic field across the bars in the rotor. So the magnetic field will rotate because of an alternating current. This comprises thin as well as stacked laminations that are wounded with the help of insulated wire. In this, the core includes the number of stacked laminations. The stator diagram is shown below.

The stator in the motor can be designed up to 22 kW aluminum, while motors including high outputs have cast-iron housings. The main function of this is to handle voltages, different frequencies, outputs & unstable poles.

Working Principle

The stator working principle is, because of the 3-phase supply, it will generate the rotary magnetic field. The function of this will change based on machines like motor, generator, and fluid powered devices. In the motor, it provides a rotary magnetic field to drive the rotary armature. In a generator, it changes the rotary magnetic field into electric current. Similarly, in fluid powered devices, it guides to flow of the fluid in the direction of the rotating part of the system.

Construction of Stator

The designing of this can be done with high-status alloy steel laminations to reduce the eddy current losses. The most important parts of this can mainly include the following.

• The Outer Frame
• Core
• Windings

Outer Frame

This frame is an outside part of the motor and the main function of this is to give support to the machine for core & inner parts. The above diagram shows its construction.

Core

The core of this can be built with silicon steel stampings and the main function of this is to hold the unbalanced magnetic field for generating eddy current as well as hysteresis losses.

In the motor, the connection of the stampings can be done with the frame, wherever every stamping can be insulated through a small varnish coating. Usually, the thickness of stamping will be changed from 0.3mm – 0.5 mm. The connections of the slots can be done within the stampings.

Windings

The core in the stator includes three-phase windings. These windings get the supply from a three-phase supply system. The windings within this will hold six terminals wherever two of each phase can be connected toward the terminal box within the machine.

The stator within the motor can be wounded for a precise no. of poles depending on the speed of the motor. If the number of poles is high, then the motor speed can be reduced. Similarly, if the no. of poles is low, then the speed of the motor will be improved.

The main relationship between the speed & the motor can be given like the following. The windings connection within the motor may be in delta or star.

Ns ∝ 1/p otherwise Ns = 120f/p

Applications

The applications/uses of stator include the following.

• It works like a field magnet in the motor based on the rotating electromotive device design.
• It interacts through the armature for creating motion otherwise it may perform like the armature to get its power from moving coils of the rotor.
• In a motor, it gives a revolving magnetic field to drive the revolving armature
• In a generator, it changes from the revolving magnetic field to electric current.
• In fluid powered devices, it guides the liquid flow to the rotary part of the system.

FAQs

1). What is the function of the stator?

The stator is used to generate a magnetic field within the air gap of the electrical machine.

2). What is the difference between the stator and the rotor?

In the motor or generator, the stator is the stationary part whereas the motor is the rotating part.

3). Which supply is used in the stator as well as the rotor?

In stator, 3-phase supply is used whereas in the rotor, dc supply is used.

4). What is the insulation in the stator & the rotor?

In stator, the insulation is heavy whereas insulation is low in the rotor.

Thus, this is all about an overview of the stator used in an electric machine. It is an inactive part of the machine. The main function of this is to generate a magnetic field within the air gap of the electric machine. Once the power supply is fed within the coils, then a magnetic field can be generated to supply throughout the air gap & get connected to the conductor of the rotor, inducing voltage within the rotor of the machine. Because of the communication in the rotor current and main flux, the torque can be produced. Here is a question for you, what is the stator core?