Q:What's the function of power capacitor?

A:It is mainly used for enhancing the power factor of the network,reducing the reactive loss and improving the voltage quality.For maximum power, voltage and current must be in phase, with their peaks coincident.In a factory, with a lot of motors, the motors use coils and present an inductive load, so voltage and current get out of phase, voltage leads.So because ExI=P, if they don't peak at the same time, you don't get maximum power (watts, which does the work) so for a given supply of voltage and current, you get less power, a lower power factor.Since capacitors are the opposite, Current leads voltage, you add capacitor banks to off set the shift caused by the inductive load, making the load appear purely resistive to the supply.