scope:

This paralleling guide describes and compares control methods of paralleling regulating transformers. The control methods include: master/follower, circulating current, power factor, circulating reactive current, and negative reactance methods. This guide presents operating philosophy descriptions, sample wiring diagrams, typical operational variations, the provision of adequate backup protection, and typical misapplication consequences. This guide does not apply to phase-shifting regulating transformers.

Purpose

The purpose of this guide is to provide power transformer paralleling users with an easily accessible source for comparing control methods of transformer paralleling. This comparison allows the proper choice of control method and proper operation to best maintain proper system operations. The guide also provides an operational understanding to assist in the analysis of changing system configurations on paralleling operations.