The objective of Phase Identification is to recognize, track and report the connectivity and loading of Phases A,B,C through the distribution system so as to prevent excessive phase imbalance.
Distribution system maps and models tend to lack reliable information about which single-phase laterals or individual customers are connected to which of the three phases. This connectivity information is not entirely static, since during restoration work such as repairs after a major storm, the phasing may be changed (deliberately or inadvertently). Historically, utilities have relied on manual notations from field crews about connectivity. In the absence of detailed records, owing to anecdotal reportings, an approximate balance – say, on the order of 10% difference in currents among phases – can usually be expected at the feeder head, but with no guarantees and occasional large departures.