Electric motors play a vital role in industries, businesses, and residential applications in the 21st century. One can find them in all electrical units like industrial fans, blowers, and machine tools. They are also an inseparable part of one’s daily domestic life. They power most of the appliances in regular households as they are found in vacuum systems, water pumps, fans, blenders, washing machines, disk drives, and other equipment. The drive for green and sustainable technology has led to the innovation of simple electric motors. Each motor has a particular application.
Basic motors are available in a wide range of designs and have various operational and safety features. Electric motors are often categorized into two broad types:
- A.C. motor
- D.C. motor
The classification is according to their power input, internal construction, and application. The identification is also based on the type of motion output.
Alternating Current (AC)
An AC electric motor operates with an alternating current voltage source. The AC electric current motors include both the synchronous motor and the induction motor. The distinction between synchronous motor and the induction motor by their resources. Synchronous motor works at a fixed speed based on the frequency of the AC supplied. They are suitable for low-load appliances like air compressors and motor generators. Synchronous motors improve the system power factor. The application of these motors is on systems that consume a lot of electricity. They are often used for both automation and robots. The validity of the synchronous motor stays high.
The induction engine uses electromagnetic induction. Induction motors are for residential, commercial, and industrial environments. The main features of the induction engines are higher dependability and solid structure. They are low-cost and low-maintenance motors. Typical uses of induction motors are in pumps, drilling machines. Portable Vacuum systems, mixers, and even some toys run on electric motors.
Direct Current (DC)
The direct current electric motor operates with a direct current voltage source. The DC motors are being utilized for heavy-duty applications. They need high starting torque. They have an efficient and modernized design for high speed and smooth running. The DC motors comprise shunt wound, series wound, compound wound, and permanent magnet motors. The main applications of DC motors are in :
- Weaving machines
- Industrial tools
- Lathe machines
- Hoist and winch machines
- Rolling machines
- Paper mills.
Some DC Series Motors have restricted use in small electrical appliances. These include appliances, electric razors, portable compact washing machines for small loads, and mini-refrigerators. The brushless DC motor has better performance than the brushed DC motors. But the functionality is lesser than AC motors.
Stepper motors use alternating current to produce rotational motion. Its application is for specific positioning machines like printing and packaging machines.
These motors use direct current and are more often used for commercial purposes. The servomotors provide smooth and controllable motion for precise results.
The linear motors use both alternate and direct currents to produce the linear motion. These motors are helpful in assembly machines, medical equipment, and material handling machines.
Air motors produce rotational motion by using air pressure.
Hydraulic motors use fluid power to produce rotational movement. These motors are in extensive use for construction machines. They are available in gear, vane, and piston types.
Gear motor applies both AC and DC to produce rotational movement. These motors are compact and work to drive other rotating machines.
Components of Electric Motors
Electric motors convert electrical energy into mechanical energy. It is generally designed for continuous rotation. Electric motors produce linear or rotary forces. This puts external mechanisms in elevators, fans, etc., in motion. Electrical motors use the power of direct current (D.C.) with sources such as batteries. They more often use the power of AC sources such as generators and electricity grids.
The main components of an electric motor are:
The armature is that component of an electric motor that carries alternating current. Armature converts electrical power to mechanical power in the form of torque. And it then transfers it through the shaft. The armature (or rotor) rotates the shaft to convert the energy into mechanical power.
It is the stationary part of an electric motor. The stator generates the rotating magnetic field around the rotor due to a three-phase supply. Stator frame, stator core, and stator winding are three parts of the stator. The stator core supports and protects the three-phase as the central part of the electromagnetic circuit. The stator’s core includes thin metal sheets to decrease energy use. The stator may have permanent windings or magnets.
The air gap is a vital element between the stator and rotor. This raises the magnetizing current. It is this distance that determines the performance of the electric motor. The air gap should be as small as possible.
Windings and Coil
The coil is an electrically conductive wire through which electricity can flow. The winding forms by connecting several coils in series. The winding cable is usually coated with copper as it is a good conductor of electricity.
The commutator is a metal cylinder-like disk on the armature shaft of an electric motor. It connects the motor to the electricity supply. It ensures that the current flowing through rotor windings is in a single direction.
Select Right Electric Motor:
Factors to consider while selecting the right electric motor are as under:
To select a suitable motor, you will need to identify the start-up point. It also depends on the power output of the machines that you will attach it to. Never join the wrong machine with the electric motor. This will result in damage to the machine and stall the equipment. Hence it is imperative to attach the right motor. Also, it should be as per the voltage of Commercial motors and residential equipment.
In AC units, one can either opt for induction machines or synchronous machine types. In DC machines, there is the option to select either brushless or brush machines.
There are several options for electric motors. NEMA (National Electrical Manufacturers Association) classifies different electric motors options. Examples of classifications are special-purpose motors, woodwork machine motors, and so on. Industrial motors classify machines in various forms like washdown duty and farm duty. NEMA classifies motors also based on insulation and temperature. Electric motors are available in several horsepowers – HP. Starting from 1hp, the power goes up till 1, 00,000hp for industrial and residential applications.
Three-phase motors run on 208 to 230 volts of power supply. Single-phase motors will run on 115 to 230 volts. Medium volt motors can range anything from 2300 to 4000 volts.
Today there are several electric motors for consumers to select from. Electric motors find use in various equipment. As per the need, one can select the electric motor for industrial as well as residential use. Consider the use of a motor for the equipment while making a purchase. Whether the electric motor is for an HVAC system, vacuum system in residential use, or power tools, compressors, industrial use, there is a wide variety of electric motors meant for every need.