what is D.C. Genetator

What is D.C. Generator:

                       A generator is a machine that converts mechanical Electricity into electric power.

Principle it works

                         It works on the principle of Faraday's Law of Electromagnetic induction. According to this law, the conductor (Armature) is rotated in the magnetic field system and e.m.f. is induced in these conductors which are collected from the commutator fitted on the shaft of the armature.

                        D.C. Generator is the machine that converts mechanical power into electric power. Then this device will give mechanical power.

  Main parts of D.C. Machine 

 Main parts of D.C. Machine:1. Body or yoke. 2. Magnetic poles and field coils. 3. Armature core and Armature winding. 4. Commutator. 5. Brushes and brush gear. 6. Shaft bearing, pulley, fan.

 1. Body or yoke. It is made of either cast iron, cast steel, or, for big machines, rolled steel. It supports the field winding

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2. Poles and field coils. The poles are either cast with a frame or bolted to it. At the end of the poles, there are pole shoes bolted to them. The poles are surrounded by field coils supplied with current usually from the machine itself for the excitation. (See Fig.1) 

3. Armature. It consists of  

• A laminated core of magnetic material,
•  Conductors in form of winding, 
• Commutator at one end of armature core.  

     The slots are cut in the core in which the conductors are placed in the form of coils. (See Fig.2). The purport of the armature is to rotate the conductors in the uniform magnetic field.

4. The Commutator. It Consists of copper segments insulated from each other and from the shaft by mica pieces. the ends of the coils wound on the armature are soldered on the segments of the commutator(see Fig 3)

                   The purpose of the commutator is to take in and deliver out the currents from the armature. is keeps the -ve and +ve terminal constant in the circuit Hence, the commutator converts A.C to D.C also.

5. The Brush Gear. It consists of two or more sets of stationary carbon brushes held in a box-type brush holder. The brushes make contact on the commutator surface with a certain amount of pressure (about 0.9 kg per 2 5 sq cm of brush area), supplied by a spring in the brush holder. The brush-holders are clamped on the spindles that are insulated from the shaft and mounted on the comb rocker.

                The rocker is capable of movement to obtain the best position for the brushes on the commutator. (See Fig. 7.1).