Basic Construction of DC Generator and it parts

    

    Do you know? There is no major difference between construction of DC generator and DC motor. In general, DC generator is a machine which converts Mechanical energy into Electrical energy. In motor the operation is vise versa.

Lets talk about the Constructional Features of DC generator. The main parts of generator are discussed one by one.

image credit: Gillett&#039, distributed under a CC BY 2.0 licenses.

Yoke

image credit: Toshinori baba, distributed under a CC BY-SA 3.0 licenses.

    The outer body or frame of the dc generator is known as yoke. The inner side of the yoke is fixed with field poles for creating the magnetic flux in the air gap.

    In general, the yoke serves the two main function

    It should give mechanical support for the field poles and protect the dc generator from surroundings. On the other hand, it provides the magnetic flux produced by the electromagnetic poles. The material used for making yoke is cast iron or cast steel

 

Pole shoe and pole core

    The arrangement of magnetic field winding is provided by inner part of yoke is known as pole shoe. By the help of former the field winding is wound in exact number of turns and then fixed with pole shoe. They spread the flux in the air gap and reduce the reluctance. 

    The pole core and pole shoe are made with lamination of steel to reduce the losses. The thickness is varied from 1 to 0.25 mm. 

 

Field coil

    To create the magnetic field between the poles the electromagnetic field coils are implemented. These coils are usually made up of copper to carry the current.

     First of all, the winding is made over the former for correct dimension and number of turns and the former wound is put over the pole cores.

 

Armature core

    The main part of dc generator is armature. the armature consists of number of conductors placed in the slots to produce the electricity when the magnetic fields are cut by armature conductors.

     It is drum shaped with laminated core. The Armature is perforated with air duct which allows the flow of air through the armature for reducing temperature.

     We can see the keyway in the armature for fix the shaft. We can reduce the losses in armature by increasing multiple number of laminations. Because of increasing resistance by decreasing the thickness of laminations.

 

Armature winding

    These are current carrying conductors when the conductors cut magnetic field produces the direction of current by Fleming right hand rule. It could also former wound and then wound on armature by automated coil puller machine. 

    The windings are made with two methods lap and wave windings. In lap winding number of paths is equal to number of conductors in wave winding the parallel path is always two.

     conductors are wound form the front end of commutator through armature. The conductors are placed in the armature slots which are wound with insulating material.

 

 Commutator

image credit: Rs1421, distributed under a CC BY-SA 3.0 licenses.

    The one of the important parts in the dc generator in commutator. The function of commutator is to facilitate collection of current from all the conductors wound on the armature. So, we can realize the number of coils is equal to number of segments.

     it converts the alternating current induced in the armature conductors in to unidirectional current in the external current having load. It is cylindrical shaped and built up with wedge shape of high conductivity.

     The segments are insulated from each other by the layers of higher resistance like mica.

 

Brushes and bearings

    The Brushes are used to collect current from the commutator. They are made with carbon or graphite and it is rectangular structure.

    The roller bearings are frequently employed for higher reliability. The ball and rollers are packed in hard oil for reduced bearing wear.

 

Conclusion

    Construction of dc motor is basic prerequisite for further with operations and winding methodology.

 

Comments

    Why the armature core is laminated in all DC generator?