A Field Method for Determining the Leading and Lagging Regulator in an Open-Delta Connection [includes discussion]

To make correct line-drop compensator settings on single-phase regulators connected open delta on a 3-phase 3-wire system, it is necessary to identify the units, commonly called leading or lagging units, in which the regulator current has been advanced or retarded by the open-delta connection. This paper describes a field method for making this identification, using only the standard regulator controls without the knowledge of phase identity or sequence and also without additional measuring or phasing equipment. The discussion includes mathematical analysis, curves, sample calculations, and laboratory analysis used in developing this method.