Understanding Reactive Power in AC Circuits: Impact of Capacitors on Total Q"

[noumed]

Assume a single-phase AC voltage applied to a series circuit with a certain impedance. Because of the real and imaginary part of the impedance, we get both real and reactive power. Now, if we were to connect a capacitor in parallel with the circuit, and if this capacitor supplies a certain amount of vars, what happens to the total reactive power of the circuit? My intuition tells me that:

P(total) is unchanged because the capacitor is purely reactive.
Q(total) = Q(source_before) = Q(source) + Q(cap)

So basically by adding that capacitor, you're reducing the the reactive power supplied by the voltage source, and thus increasing the power factor. Am I right?

 

[m.s.j]

Yes, indeed capacitor is a static reactive power generator.


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[noumed]

Thanks! =]

 

[Pumblechook]

You need to look up 'Power Factor Correction".

Poor power factor will increase real power loss because a higher current will flow in the wiring and the generator has to be capable of supplying the higher current.