Electric Circuits and Networks, Ist Edition by Pearson

reactive elements. If V  V

rms

∠

φ

v

and I  I

rms

∠

φ

i

are the voltage phasor and current phasor

at load terminals as per the passive sign convention, then the Q delivered to the load circuit

is V

rms

I

rms

sin (

φ

v

–

φ

i

) VAr. The other expressions are relevant when the voltage phasor and/or

current phasor across a pure reactive element is known. In this case (

φ

v

–

φ

i

) is assured to

be 90° if the element is an inductor and –90° if the element is a capacitor. Then, the reactive

power delivered to that element, i.e., Q is given by , where V

rms

is the rms value of the voltage across the element, I

rms

is the rms value of current through

the element and X is the reactance ...