What is generator-: A generator is a machine which converts mechanical energy into electrical energy. The energy conversion is based on the principle of the production of dynamically induced e.m.f. whenever a conductor cuts
Types of Generator
- Ac generator
A.C (Alternating Current)Generator or Alternator-: Ac generator operates on the same fundamental principle of electromagnetic induction. It consists of an armature winding and a magnetic field. when the flux linking a conductor
- DC generator
D.C (Direct Current)Generator-: A DC generator is an electrical device which converts mechanical energy into electrical energy. These types of generator is
From basic side a generator have two essential components(a) A magnetic field.
(b) A conductor or conductors which can so move as to cut the flux.
A generator consists of the following essential parts(1) Magnetic frame or Yoke
Magnetic frame or Yoke-: It is made of cast or rolled Steel. It provides support for the poles and protecting the whole electrical machine. It also carries magnetic flux produced by the by the field winding.
(2) Pole coils or Field coil
Pole coils or Field coil-: The function of the field system is to produce uniform magnetic field within which the armature rotate. It consists of a number of salient poles bolted to the inside of circular frame the Yoke is usually made of solid cast Steel whereas the pole pieces are composed of stacked lamination. by reducing the length of air gap we can reduced the size of field coils.
(3) Armature winding or conductors
Armature winding or Conductors-: Armature winding the slots of the armature core hold insulated conductor that are connected in a suitable manner this is known as armature winding. armature winding is the main current carrying winding in which the electromotive force or counter e.m.f of rotation is induced. The armature winding of a D.C machine is a closed circuit winding the conductor being connected in a symmetrical manner forming a closed loop or series of closed loops.
(4) Brushes and bearing
Brushes and Bearing-: The function of brushes is to collect current from commutator are usually made of carbon or graphite and in the shape of a rectangular block. Bush bearing, ball bearing, roller bearing is used and fitted with site-cover to minimize friction. Sleeve bearing are used which are lubricated by ring oil fed from oil reservoir in the bearing bracket.
Exp.– electric motors, alternators and electric generators.
(5) Pole cores and Pole shoes
Pole cores and Pole shoes–: Pole core is made of cast steel and usually of circular section and used to carry in insulated coil carrying field current. Poles are joined to the yoke with the help of bolts or welding.Pole shoes can support the field coil for its laminated.
(6) Armature Core
Armature Core-: It consists of a laminated core of magnetic material and conductors in from of winding. The armature is an electromagnet made by coiling thin wire around two or more poles of a metal core. It’s very important purpose is to provide a part of very low reactance to the magnetic flux. The slots are in the core in which the conductor is placed in the form of coil. The armature is to rotate the conductors in the uniform magnetic field.
Commutator-: A commutator is consisting of copper segment insulated from each other and these segments are insulated from each other by thin layer of mica. It consists of a cylinder composed of multiple metal contact segments on the rotating armature of the machine or drop forged copper. It convert A.C induced in armature conductor into D.C in the load circuit.
Shaft-: A shaft is made of mild steel it will be used to transmit power from one part to an other.which carries armature, connector, cooling fan, bearing etc.
How many types of armature winding see in a generator
(1) Lap Winding–: Lap winding- In this arrangement, the armature coil is connected in series through commutator segment in such a way that the armature winding is divided into as many parallel paths as the number of poles of the machine.Number of parallel path on the armature is equal to number of pole. Each parallel paths will carry a current of Ia/P. Lap-wound armatures used in dc generators require several pairs of poles and brushes.
here [Ia- Armature current & P- Number of Pole].
(2) Wave winding-: The armature coil are connected in series through commutator segment in such a way that the armature winding is divided into two parallel paths . In these type of winding used to carry more voltage and less current.
Example Of GeneratorGas Turbine Generator
- Gas Turbine Generator-: These type of generator is the engine at the heart of the power plant that produces electric current.
- Diesel Generator-: These type of generator is the combination of a diesel engine with an electric generator to generate electrical energy.