Method and system for assessing and managing an electrical unbalance condition associated with a three-phase electrical system. An Intelligent Electronic Device (IED) coupled to the load acquires energy-related signals associated with the electrical system. A processor is configured to characterize electrical unbalance between a plurality of conductors analyze data associated with the characterization to identify electrical unbalance across the plurality of conductors, and determine the extent of the contribution of the electrical source(s), and the extent of the contribution of the load(s) in the electrical system, to the identified electrical unbalance condition.

Apparatuses and methods herein provide a voltage imbalance detector that employs two solenoid coils, each coil coaxially arranged around a slidable metal plunger on opposite sides thereof. One coil is electrically connected to one line of a 120 V/240 V power supply and to neutral, while the other coil is electrically connected to the other line of the 120 V/240 V power supply and to neutral. When the coils are energized by current from the power supply, each coil induces an equal but opposite electromagnetic force acting on the metal plunger if the power supply voltages are balanced, thereby maintaining the plunger stationary relative to the coils. But if the voltages are not balanced, then one coil will induce a greater (or lesser) electromagnetic force than the other coil, resulting in the plunger moving toward (or away from) the first coil, thereby sensing the voltage imbalance.

A fault detection circuit according to the present disclosure includes a rectangular pulse comparison circuit configured to generate, for each combination of the pulse width modulated signals, detection signals each indicating a difference component between pulse widths of two pulse width modulated signals having phases adjacent to each other, and a fault diagnosis unit configured to detect a fault in an inverter based on a shift in a combination of logic levels of a plurality of the detection signals output by the rectangular pulse comparison circuit from a preset determination value. The fault diagnosis unit uses the determination value that is different for each motor rotation angle assuming in advance that two alternating-current signals having phases adjacent to each other among the three-phase alternating-current signals have the same voltage.

A fault detection circuit according to the present disclosure includes a rectangular pulse comparison circuit configured to generate, for each combination of the pulse width modulated signals, detection signals each indicating a difference component between pulse widths of two pulse width modulated signals having phases adjacent to each other, and a fault diagnosis unit configured to detect a fault in an inverter based on a shift in a combination of logic levels of a plurality of the detection signals output by the rectangular pulse comparison circuit from a preset determination value. The fault diagnosis unit uses the determination value that is different for each motor rotation angle assuming in advance that two alternating-current signals having phases adjacent to each other among the three-phase alternating-current signals have the same voltage.

Method and system for assessing and managing an electrical unbalance condition associated with a three-phase electrical system. An Intelligent Electronic Device (IED) coupled to the load acquires energy-related signals associated with the electrical system. A processor is configured to characterize electrical unbalance between a plurality of conductors analyze data associated with the characterization to identify electrical unbalance across the plurality of conductors, and determine the extent of the contribution of the electrical source(s), and the extent of the contribution of the load(s) in the electrical system, to the identified electrical unbalance condition.

Method and system for assessing and managing an electrical unbalance condition associated with a three-phase electrical system. An Intelligent Electronic Device (IED) coupled to the load acquires energy-related signals associated with the electrical system. A processor is configured to characterize electrical unbalance between a plurality of conductors analyze data associated with the characterization to identify electrical unbalance across the plurality of conductors, and determine the extent of the contribution of the electrical source(s), and the extent of the contribution of the load(s) in the electrical system, to the identified electrical unbalance condition.