03-12-2012, 01:14 PM
SERIES AND PAREALLEL RESONANCE
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THEORY:
Resonance is a particular type of phenomenon inherently found normally in every kind of system, electrical, mechanical, optical, Acoustical
and even atomic. There are several definitions of resonance. But, the most frequently used definition of resonance in electrical system is studied state operation
of a circuit or system at that frequency for which the resultant response is in time phase with the forcing function.
Series resonance:
A circuit is said to be under resonance, when the applied voltage ‘V’ and current are in phase. Thus a series RLC circuit, under resonance behaves like
a pure resistance network and the reactance of the circuit should be zero. Since V & I are in phase, the power factor is unity at resonance.
The frequency at which the resonance will occur is known as resonant frequency.
Parallel Resonance:
The parallel circuit consisting branches with single pure elements R,L & C is an ideal circuit. How ever the performance of such a circuit is
of interest in the general subject of resonance. This ideal parallel circuit is of interest in the general subject of resonance.
Lower cut-off frequency is above the resonant frequency at which the current is reduced to times of it’s minimum value. Upper cut-off frequency is
above.
Quality factor is the ratio of reactance power inductor (or) capacitor to its resistance. Selectivity is the reciprocal of the quality factors.