Electric Motor

An electric motor is a device that powers various electronic machines, such as fans, washing machines, etc, by conversion of energy from one form to another. In the case of an electric motor, electric energy is converted into mechanical energy. In simple words, it can be said that the electric motor is a device used to move things via electricity making it an essential element of various everyday use appliances. 

1.0Principle Of An Electric Motor

Electric motors operate on the principle of electromagnetic induction, a process in which a current-carrying conductor placed in the magnetic field experiences a force. This is the force that pushes the conductor to move, resulting in the conversion of electrical energy to mechanical motion. 

To understand it more clearly, imagine a horseshoe magnet and place a current-carrying rectangular coil in between the poles of the magnet. Open the circuit, and the coil carrying the current will start moving under the influence of the current and magnetic field produced by the magnetic. Analyse the following electric motor diagram: 

The current carrying coil doesn’t move in any direction; rather, it follows the flemings’ left-hand rule to determine its direction. According to this rule, When you hold your left hand with all three fingers perpendicular to each other, you will know the direction of the conductor. In the Flemings’ left-hand rule: 

• Thumb: It represents the direction of motion or force in which the object is moving. 
• Index finger: It represents the direction of the magnetic field from north to south. 
• Middle finger: It shows the direction of the electric current in the conductor (positive to negative terminal)

2.0Main Components of an Electric Motor

An electric motor is made up of various components, which include: 

1. Stator: The part of the motor which is stationary; it has a magnetic field produced by permanent magnets or electromagnets.
2. Rotor: The moving part of the motor that reacts to the magnetic field to cause movement.
3. Commutator (in DC motors): A device which reverses the direction of the flow of the current in the coil, hence, the rotor would continue to move in the same direction.
4. Brushes (in DC motors): Conductive materials that make contact with the commutator to supply current to the rotor.
5. Armature: The coil of wire attached to the rotor, which carries the current and produces the magnetic field.
6. Shaft: A rotating part that transfers mechanical energy to the load (e.g., a fan blade or a wheel).

3.0Electric Motor Winding

Motor winding is the process of wrapping copper wire coils around the stator or rotor of an electric motor. These windings play a critical role in developing the magnetic field required for the motor to operate. A winding carries the electrical current, which serves to generate the magnetic field that interacts with other parts of the motor to produce motion or mechanical energy. Electric Motor winding affects the efficiency and performance of the motor, which in turn depends on: 

• The number of turns in copper coils 
• The arrangement of windings 
• Type of material used in the motor

4.0Types of Electric Motors

Electric Motors are basically of two types based on the current that is AC or DC, which are further divided into sub-types: 

1. DC Electric Motors: As the name suggests, it works on direct current (DC) electricity. It periodically changes the direction of current in the armature by the commutator and brushes. It is used in small devices like toys, fans, and electric windows of cars. 
2. AC Motors: AC Motors operates on alternating current (AC) electricity, a more commonly used electric motor in industrial and household usage. It is further divided into: 

• Synchronous Motors: The rotor rotates at constant speed synchronously with the supply frequency.
• Induction Electric Motors: The rotor is induced by the magnetic field of the stator, and it rotates at a speed that is slightly lower than the synchronous speed.

3. 3-Phase Electric Motor: A 3-phase electric motor is a class of AC motors powered by three-phase electric power. In this type of electric motor, three alternating currents, namely the ACs, travel to the motor. These three currents generate a rotating magnetic field within the motor. The rotation of this magnetic field causes the motor’s rotor to turn.
4. 12V DC Electric Motor: Originally it is the smaller version of DC motors, which is powered by a 12V DC battery or power supply. It is widely used for low-voltage devices such as toys and model vehicles. 
5. Water Pump Electric Motor: It is the type of AC or DC motor specifically used in operating the water pump for irrigation, water supply, and drainage systems.