Generator EMF Equation
The generator works on the principle of Faraday's laws of electromagnetic induction. When a conductor cuts the magnetic lines of flux e.m.f. (electro motive force) is induced in it. This emf
is a dynamically induced e.m.f.
is a dynamically induced e.m.f.
The emf generated in a P-pole DC generator is calculated as given below
The emf generated in a conductor is given by \[\frac{d∅}{dt}\] V.
As generators have many conductors, the average emf per conductor is calculated.
The average emf generated per conductor is given as \[\frac{d∅}{dt}\] V.
Where, ∅ is the magnetic flux per pole in weber.
If the armature of the generator is rotating at a speed of N revolutions per minute (rpm) then for one revolution the flux cut by a conductor is d∅ = ∅P Wb.
The time take for one revolution is dt = 1/N min = 60/N sec.
Therefore the emf generated per conductor is given as,
\[\frac{d∅}{dt}\]=\[\frac{∅PN}{60}\] volt.
If Z is the total number of armature conductors (=number of armature slots X number of conductors per slots) and A is the number of parallel paths.
Then the emf generated per path is given by,
Eg=\[\frac{∅PNZ}{60xA}\
A = 2 for simplex wave winding. As the wave winding has only two parallel paths.
A = P (number of Poles) for simplex lap winding.
If the speed of the generator is given in radians / second then the emf equation can be given as,
Eg=\[\frac{∅P(2πN)Z}{2πx60xA}\=\[\frac{∅PωZ}{2πx60xA}\.
Where ω = speed in rad/s
In a DC machine the values P, Z, A are constant and thus the equation can be expressed as,
Eg=Kg∅N v.
Where Ka=PZ/60A
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