What is Phase Imbalance?


Phase unbalance of a three-phase system exists when one or more of the line-to-line voltages in a three-phase system are mismatched. Three-phase power systems and equipment are intended to operate with phases (Lines) balanced. Line-to-line voltages in a three-phase circuit typically vary by a few volts, but a difference that exceeds 1% can damage motors and equipment. The unbalanced voltages cause unbalanced current in the motor windings; unbalanced currents mean an increase of current to at least one winding raising that winding temperature. Increased temperature reduces motor or equipment life leading to premature failure.

Why it Matters

A phase unbalance may be caused by unstable utility supply, unbalanced transformer bank, unevenly distributed single-phase loads on the same power system, or unidentified single-phase to ground faults. Single phasing (phase loss) caused by utility supply faults, broken wires, failed fuses, damaged contacts, or malfunctioning overloads can also result in damaging unbalance conditions.

A building monitoring system is a cost-effective and easy to install solution to prevent costly damage from phase unbalance to your motors and equipment. A building monitoring system protects against premature equipment failure by monitoring for several common fault conditions including phase unbalance. it notifies of a fault condition and encourages operators to turn off equipment or motor before damage occurs. A clear indication of the fault present is provided in data visualizations for rapid troubleshooting and reduced downtime.

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