Originally Posted By: exranger06
Yes, that's what I said. Of course they want the meters to read properly. But maintaining a good power factor is essential to keep the whole system operating properly. They also need to maintain a good power factor to be in compliance with regulatory authorities.
Inadequate reactive power = voltage collapse, which really, really isn't good for the overall customer experience. The design engineer of a plant (or a utility) needs to consider reactive power requirements over the entire cycle -- winter, summer (ie: AC loads), cold days and hot days.
To top it all off, if there's too many capacitors in a system, under certain conditions, resonance can develop (after all, power systems are full of R, L, and if you add C -- you get a classic resonant RLC filter). In some extreme cases, subsynchronous resonance (ie: resonant modes beneath system frequency) can migrate back to the generators and destroy them. Again, stuff that has to be considered by professionals.
In some cases, where the need for VArs varies quickly/frequently (ie: electric arc furnaces are notorious culprits), machines called "Static Var Compensators" are used. Basically instead of a switch to switch a capacitor on and off, they use a transistor )(called a "thyristor") that can be switched on and off at high speeds using feedback control.
