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Q: Do you believe that volt/VAR optimization based on single-phase capacitor bank switching (rather than three-phase switching) that minimizes both energy consumption and feeder voltage balancing index will be more prevalent in the future on feeders without voltage regulators?
Anonymous, United States

A: There is some small gain associated with the single-phase cap bank switching. However, for most utilities in small to large towns and cities the three phase circuits are very well balanced (most of the time). Therefore switching capacitors independently in all three phases provides only small benefit at an increase cost in terms of sensing, controls, and communications (if there is any). One would have to perform a ROI analysis of whether the single-phase cap switching would be better than three-phase switching. A slightly different answer could be for utilities operating in the rural areas where the feeders are long and end of the line is only a single-phase anyway. There, at lest in some cases, the unbalance (in terms of VARs as well as voltage regulation) between the phases could be more significant. But again, one would have to assess a ROI for such applications, because typically these long, rural feeders have lower priorities in terms of investments, VAR management, losses, etc.
Dr. Mietek Glinkowski, P.E.
Global Head of Technology, Data Centers
and Director of Technology, Power Products

ABB

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