ABSTRACT
Regulating power transformers, three-phase step-voltage regulators, and single-phase step-voltage regulators are typical transformer-type equipment used to improve the voltage “profile” of a power system. Single-phase step-voltage regulators maintain a constant voltage by on-load voltage regulation wherever the voltage magnitude is beyond specified upper and lower limits. The combination of step-voltage regulators and fixed-ratio power transformers is often used in lieu of on-load-tap-changing transformers (OLTC) power transformers in the substation. The combination of step-voltage regulators and fixed-ratio power transformers is often used in lieu of OLTC power transformers in the substation. Three-phase power can be regulated by a bank of three single-phase step-voltage regulators connected in wye for a four-wire circuit or two or three single-phase regulators connected in an open- or closed-delta configuration for a three-wire circuit. In a voltage regulator, the equivalent of the high-voltage winding in a two-winding transformer would be referred to as the shunt winding.
