The application of single-phase voltage regulators on three-phase distribution systems

Voltage regulators are applied on distribution systems to control the voltage delivered to customers within acceptable industry standards. Concerns about the quality of electric power delivered to customers by electric utility companies have raised the level of awareness of high and low voltage conditions at customer facilities. Normally occurring voltage drops through lines end transformers vary with the load level on the system. Voltage regulators, when properly applied, can compensate for these voltage drops and keep customer voltage within proper limits. Single-phase voltage regulators can be applied on three-phase systems in a variety of ways, including grounded-wye, open-wye, closed-delta, and open-delta. The capabilities of the regulator systems are effected by the system design. This paper reviews the characteristics of the closed-delta and wye applications, and discusses the advantages and disadvantages of each application scheme. The impact of the regulator connection on the overcurrent protection scheme is also reviewed