Capacitors and Automatic Boosters for Economical Correction of Voltage on Distribution Circuits

Analysis of operating characteristics shows that fixed shunt capacitors may be used to provide voltage correction up to approximately three per cent on a typical four-kv distribution circuit. Installation of capacitors up to this limit, or to unity power factor on the feeder if that occurs with less capacity, generally gives voltage improvement at minimum cost. Additional correction can be secured with a set of automatic voltage boosters beyond the shunt capacitors, except that single-phase taps from near the feeding point should have the other phases extended first to secure lowest cost. This procedure requires only three different devices, a 30-kva single-phase capacitor, a 90-to 180-kva three-phase capacitor, and a 5-kva automatic booster with two 1.33-percent steps, to secure appreciable economies in distribution cost.