Automatic Phase Balancing Method for Rack or Cabinet Power Distribution Units
Publication Date: 2011-Sep-20
The IP.com Prior Art Database
Described is a design for intelligent, automatic phase balancing within a rack power distribution unit (PDU). The automatic method eliminates the need to take measurements and the complication of manually repositioning equipment by physically moving PDU output receptacle jumper cords from one receptacle to another (e.g., unplug and re-plug equipment powered from the PDU).
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Rack or cabinet power distribution units (PDUs) with three-phase input typically require manual placement across the output receptacles to balance the equipment loads across the phases. Facility phase balancing is important to use feeder capacity efficiently, to equalize voltage drops in the electrical distribution, and to provide specified reserve capacity. Unbalanced equipment loads can also result in inefficiencies with three phase transformers and premature overloading of uninterruptible power supplies (UPSs).
This disclosure shows an automatic method that uses a series of three position switches or back-to-back FETs (zero crossing detection) controlled by local processors (LPs) and a central processor (CP) to balance equipment loads across the phases. Each of the switches can connect the one of two current lines (A, B, or C) and has one open position. The local processors measure amperages, control the switching to keep from shorting (break before make) and ensure proper phase connection. The central processors collect the amperages from all the local processors and make balancing decisions based on the rules that are encoded.
The basic rules include, but not limited to, a circuit breaker overload check and a balancing check (e.g., need to analyze all combinations to either take the best combination or be within a certain percentage across phases).
A PDU link processor (PLP) is used to communicate with a...