INTRODUCTION
To convert energy from one form to another a machine is
required .In the D.C Machine the energy conservation is based on the production
of dynamical induced emf .The machine which converts mechanical energy into
electrical energy is called a Generator. The machine which converts mechanical
energy into electrical energy is called a D.C Generator and when electrical
energy is converted into mechanical energy , it is called D.C motor. All these conversions take placed through the medium of magnetism. As such magnetism plays an important role in the
energy conversation and so also its laws. Since the conversation is bilateral
from electrical to mechanical and vice –versa , the machine which operates as a
generator can also be operated as motor and as such the construction features
are same . The basic law which is applicable in the D.C Machine is Faraday’sLaws of Electro-magnetic induction for which the essential requirements are
- Conductor
- Flux
- Conductor process cut the flux
PRINCIPLE OF OPERATION
The
principle of operation is based on the Faraday’s Laws of electromagneticinduction which states that
- Whenever a conductor cuts the magnetic field an emf is induced in the conductor
- The magnitude of induced emf is proportional to the rate of change of flux linkages
- · Such induced e.m.f will last only as long as the flux linkage exists
Mathematically the law can be
expressed as
Let N = No of turns of
the coil
ᶲ1 = Initial flux through
the coil (Wb)
ᶲ2 = Final flux through the coil (Wb)
t = time in seconds
during which the flux changes from ᶲ1 to ᶲ2 Wb
Since flux linkage is the product of
flux and number of turns
Initial flux linkage = Nᶲ1
Initial flux linkage = Nᶲ2
Change of flux linkage N(ᶲ2-ᶲ1)
Therefore, e.m.f induced in the coil
is propotional to the rate of change of flux linkages
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