ABSTRACT
Capacitors can be manufactured as relatively small elements, both in terms of their reactive power rating and their operating voltage. Capacitor banks and individual capacitors can therefore form either fixed installations, which are always connected when that section of the plant is running, or be switched when required. Capacitor units are supplied in three basic configurations: externally fused, internally fused, and fuseless designs. Individual outdoor capacitors are usually designed for rack mounting on an insulated structure, using individual or group fusing, together with accessories such as switching devices and control facilities. For any switched-capacitor scheme, the switching devices must be rated for capacitor switching and have a voltage rating greater than the associated maximum system operating voltage. The momentary rating of the switching devices should withstand short-circuit currents for faults and the high-frequency inrush currents associated with switching capacitors. Air-insulated capacitor banks are constructed on metal frames and are often floor mounted and hence are dangerous to approach.
