An alternator is an electrical apparatus which converts mechanical energy into alternating electric energy. They are also called as synchronous generators.working principle of alternator Accordingly, Faraday’s Laws of Electromagnetic Induction, the e.m.f. induced in the twine is given by the rate of change of flux linkage of the coil.
Working Principle of Alternator:
An alternators (as they are generally called) move on the same basic morals of electromagnetic induction as D.C. generators. the swiftness at which the coil or magnetic field rotates.
Consider a rectangular coil having N turns and rotating in a similar magnetic field with an angular velocity of w radian/second. Maximum flux Øm is connected with the coil when its plane be gathered with the X-axis. In time t seconds, this coil rotates with an angle q = wt. In this alter position, the element of the flux which is perpendicular to the plane of the coil is Ø= Øm cos wt. Hence flux linkage analysis at any time is NØ=NØm cos wt.
Accordingly, Faraday’s Laws of Electromagnetic Induction, the e.m.f. induced in the twine is given by the rate of change of flux linkage of the coil. Since the value of the founded e.m.f. is
e = – d(NØ)/dt volt
= – Nd(Øm cos wt)/dt volt
= – NØm w(-sin wt) volt
= wNØm sin wt volt
= w NØm sin q volt ———————– (i)
When the coil turned through 90º i.e. when q = 90º, then sin q = 1, since e has maximum value, say Em.from Eq(i) we get,
Em = wNØm
= w NBmA = 2pfNBmA volt
where Bm = maximum flux density in Wb/m2.
A = Area of the coil in m2.
f = frequency of turning of the coil in rev/second.
Substituting this value of Em in Equation(i), we get
e =Em sin q = Em sin wt
Similarly, the induced alternating current is
i = Im sin wt