Hi,
first of all in ac we have " 3 types of power " : apparent power [VA], active power [W] and reactive power [VAr].
Now to your questions (without formula :grin: ) : i belive a more intuitive explication is offered by treating the subject under energetical aspects:
- the active power [w] is the power that is produced ( power plant ) and consumed, converted in other forms of energy ( electric recivers ) .
- reactive power is produced in electro-energetic systems by elements which have inductive and capacitive characteristics and the difference is that this kind of electric power is not consumed and usefully transformed in other forms of energy by electric recivers , it is a transferred power (i call it ping-pong power :grin: ) which only over charges power lines (increses the current) That is why the need of compensation exists in such electroenergetical systems.
About compensation.
Reactive power can be of 2 types starting by the produceing element (condensator type or coil type ) : capacitive VAr and inductive VAr . If in a system VAr circulation is produced by coil type reactive elements then the compensation can be made by capacitive type of elements or by other elements that can perform a capacitive characteristic (for example the synchronous compensator can work in capacitive domains and inductive domains). In the same way capacive VAr can compensate inductive VAr.
Now how do i distinguish inductive VAr from capacitive VAr ?
It is simple : from phase shift of current and voltage. By inductors first the voltage passes thro zero (we are in AC) and then the current. By capacitors voltage passes thro zero after the current
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some graphic (no formula)