Education and Career Forum

what is difference between "ACTIVE POWER" and "REACTIVE POWER"?
what is the relationship between them?

Hi,

consider an ideal alternating current (ac) circuit consisting of a source and a generalized load, where both the current and voltage are sinusoidal. If the load is purely resistive, the two quantities reverse their polarity at the same time, the direction of energy flow does not reverse, and only real power flows. If the load is purely reactive, then the voltage and current are 90 degrees out of phase and there is no net power flow. This energy flowing backwards and forwards is known as reactive power.


Important terms used:-


real power (p) [unit: W]
reactive power (q) [unit: Var]
complex power (s)
apparent power (|s|) [unit: Va]: I.e. The absolute value of complex power s.


Q=v*i*sin@
but sin@=x/z
so q=v*i*x/z
agian v/z=i
so q=i(sqr)x

since there is no any power loss when current flows through
the pure inductor or capacitor, but the energy is stored in
the form of magnetic field(in inductor) or static field (in
capacitor). So the reactive power is the power used for
magnetizing or is stored in capacitor in the form of static
field.

Simillarly

p=v*i*cos@
but cos@=r/z
so p=v*i*r/z
also v/z=i
so p=i(sqr)r


this is the formula for heat loss in the system. Actully no any system is loss less. So active power is the power that is lost in the form of heat in the systeor we can say active is the power used in the system to compensate for loss.

Hope this helps..

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