Generators

A generator (or an electric generator) is a device used for generating electrical power by converting mechanical energy (motive power) into electrical energy for use in an electric circuit. Sources of mechanical energy include water turbines, hydraulic press, internal combustion engines, fuels, etc.

• Electric generators are made on the principle of electromagnetic induction.
• Generators can be of two types- one is DC generator (Dynamo) and the second is AC generator (Alternator).
• Generators are a source of almost all of the power for electric power grids.

Principles Used In An Electric Generator

1. Faraday’s law of induction:- Faraday’s law of induction is a basic law of electromagnetism forecasting how a magnetic field is going to work with an electric circuit to produce a phenomenon of an electromotive force (EMF) called electromagnetic induction. It is the fundamental principle that is operated for generators and other such kinds of machines.
2. Fleming’s right hand rule:- According to this rule, the thumb represents the direction of Motion of the conductor. The first finger signifies the direction of the Field (north to south).  The Second finger signifies the direction of the induced current (the direction of the induced current will be the direction of conventional current moving from positive to negative).

What is a DC Generator

A generator that produces direct current from mechanical energy is called a DC generator (or dynamo). In the past, this was the only convenient way to produce electrical energy.

Its Principle and Working:

If a conductor cuts magnetic lines of force, electromagnetic force is generated in the conductor, and the electromagnetic force produced will vary with the number of magnetic lines of force, number of conductors (i.e. the number of coil windings), and the speed at which the conductor cuts the lines of magnetic. The current generated is then assembled by using an external electric circuit. If a conductor is turned clockwise between the north and south poles of a magnet, emf will be produced in the direction as stated in the Fleming’s right hand rule.

Parts Of A DC Generator

A DC generator is generally comprised of following parts:-

1. Pole cores:- Poles cores become the north and south poles of a magnet when the current flows through field coils. Most of the generators have four poles.
2. Field windings:- It is used as an insulating medium to wound wire in coil form and fix around the pole cores 
3. Armature:- It is a shaft that rotates inside the pole cores and produces the electromotive force. It consists of a rotating shaft with the armature coil at the center.
4. Commutator:- It turns Alternating Current to Direct Current.
5. Brushes:- It contacts against the commutator and passes the current produced in the armature to the field coil and to the outside of the generator. It is made up of carbon.
6. Pulley:- It is provided with a fan to lessen the temperature of the generator.

Attributes Of A DC Generator

• Electromagnetic force generated by a generator tends to be larger with increasing amount of discharge. 
• Continued high speed operation causes large current to flow through the battery, generator and other electric circuits and shorten their service tenure. 
• During low speed, only small current flows.
•  A DC generator is provided with a regulator to prevent the fluctuation in speed.

What Is An AC Generator

A generator which produces alternating current from mechanical energy is called an AC Generator (or Alternator).

Its Principle and Working:

An alternator is designed to change mechanical energy into electrical energy. The principle an alternator works upon is electromagnetic induction (EMI). When the rotor rotates, its magnetic field cuts across the stator windings. This stimulates current in the stator windings. If the stator windings are connected to a load (Eg- bulb), the load would operate. Its distinguishable feature is that slip rings are used in it.

Attributes Of An AC Generator

• The capacity of an AC Generator is not limited like a DC Generator. 
• An AC generator is the support system of the vehicle’s electrical system when the motors (or engines) are in working state. It makes use of the mechanism of electromagnetic induction to turn some motors (or engines) from motive power into electric current.
• There exist mainly two kinds of AC generators –one is the conventional type that was used previously the most and the second one is the separate voltage regulator type.

Construction Of An AC Generator

An AC generator is generally composed of components mentioned below:-

• Stator:- It is a  component of a rotary system which doesn’t move i.e. it remains stationary. 

• Rotor:- These are the large discs made up of metals. It is a moving component i.e. it keeps spinning.

• Bracket:- It is a supporting tool that lifts, holds, or keeps an object which can be heavy.

• Brushes:- It helps to move current to the coils.

• Rectifier:- It is used to convert Alternating current to Direct current as and when the Direct current is needed instead of alternating current. An electric current can be rectified from Alternating current to Direct current by applying any suitable method from the good amount of available methods.

Conclusion

To sum up, Generators are very crucial devices holding various applications worldwide by producing electrical energy from mechanical energy. There are two types of generators – AC generator & DC generator. The mechanisms, workings, Physical parts and characteristics of both types of generators have been discussed above.