An embodiment relates to a switchgear for a single-phase motor and a three-phase motor, the switchgear including a processing unit and a first, second and third current path, the first and third current path each including a current transformer. The processing unit is adapted to detect the current I.sub.1 of the first current path and the current I.sub.3 of the third current path. To provide a cost-effective switchgear for a one-phase motor and a three-phase motor which is adapted to identify the failure of every single phase in the three-phase operation and a phase failure in the one-phase operation, the processing unit is designed such as to detect the currents I.sub.1, I.sub.3 of the first and third current path and to determine, based on the phase shift between the detected currents I.sub.1, I.sub.3 of the first and third current path in which operating mode the switchgear is operated.

A method comprises, at a power balancing circuit for three-phase AC power: feeding three power phases to respective loads; measuring power drain on the three power phases by the respective loads; based on measuring, detecting an unbalanced power drain across the three power phases due to a relatively light power drain on one or more lightly loaded power phases and a relatively high power drain on one or more heavily loaded power phases; computing an amount of power to be drained from the one or more lightly loaded power phases and to be fed to the one or more heavily loaded power phases to balance the power drain across the three power phases; and transferring the amount of power from the one or more lightly loaded power phases to the one or more heavily loaded power phases to balance the power drain across the three power phases.

The present disclosure relates to a reactive power compensation system including a reactive power compensation unit for measuring compensate reactive power, an impedance measurement unit for measuring an impedance value of each of a plurality of loads, and a learning control unit for controlling the reactive power compensation unit based on the measured impedance value.

A virtual co-phase power supply system topology suitable for an electrical sectioning device at a sectioning and paralleling post (SP) includes a step-down transformer TR.sub.1. A primary winding of the step-down transformer TR.sub.1 is electrically connected to a traction feeding section β.sub.2 in a train from a traction feeding section β.sub.1 to the traction feeding section β.sub.2. Each secondary winding is electrically connected to one rectifier separately. DC buses output from the rectifiers are connected in parallel. The other end of the DC bus is electrically connected to a plurality of parallel inverter units. An LC filter is provided on a DC bus between a rectifier unit and the inverter unit, and the LC filter is connected in parallel to an energy storage unit. After filtering through the LC filter, an output end of the inverter unit is electrically connected to a primary winding of a step-up transformer TR.sub.2.

Current imbalance may be detected and components reactively moved to correct the current imbalance. The components, such as rectifiers, machines, etc., may be moved from the most loaded phase to the least loaded phase. The imbalance may be detected at one or more power distribution units. Rebalancing may be performed using a model which preserves the number of components per rack, while limiting per-rack phase imbalance and minimizing imbalance among phases. Once the rebalancing has been computed, instructions for moving components according to the rebalancing may be generated.

A method for operating a charging device of an electrical energy store for a motor vehicle, wherein a dedicated rectifier device for generating a charging voltage for the electrical energy store is associated with each phase of an AC power supply, includes determining for each rectifier device a usage variable descriptive of its prior usage for charging the electrical energy store; when performing a multi-phase charging operation with the charging device, using for each phase a corresponding rectifier device for generating the charging voltage for the electrical energy store; and when performing a single-phase charging operation with the charging device, using the hitherto most underused rectifier device for generating the charging voltage for the electrical energy store based on the usage variable.

A load balancing apparatus for balancing the current supplied on each phase of a multiple phase supply, Each supply phase feeds an AC load, as well as an AC-DC converter. The apparatus measures the current supplied from each phase of the supply as well as the power consumed by each of the AC loads. The power consumed by each of the AC-DC converters is adjusted so that the sum of the current drawn by any one of the AC loads, plus the current drawn by the AC-DC converter on the same supply phase, is substantially balanced between the supply phases. Typically the AC-DC converters supply a common DC battery. In some embodiments each AC load includes a DC-AC converter configured to supply power from the common DC battery to one or more of the AC loads.

A system and method for detecting and localizing excess voltage drop in single or multiple phases of three-phase AC circuits is disclosed. An electrical distribution circuit is provided that includes an input connectable to an AC source, an output connectable to terminals of an electrical machine, the output configured to provide three-phase voltages and currents to the electrical machine, and a diagnostic system configured to detect an excess voltage drop (EVD) in the electrical distribution circuit. The diagnostic system includes a processor that is programmed to receive measurements of the three-phase voltages and currents provided to the electrical machine, compute a negative sequence voltage from the three-phase voltages and currents, determine a localization reference phase angle for each phase based in part on the three-phase voltages and currents, and calculate an EVD in the electrical distribution circuit based on the negative sequence voltage and the localization reference phase angles.

Methods, systems, and devices for portable load balancing and source optimization are described herein. One portable load balancing and source optimization system, includes one or more electric generators that supply three phase electrical power, at least one sensor to sense whether the three phases have become unbalanced beyond a threshold amount, a set of contactors that enable the contacts of the three phases to be changed to adjust the balance of the three phases, and a controller to determine which reversible contactors of the set of contactors to change to adjust that balance of the three phases based on information from the sensor.

Aspects of the subject disclosure may include, for example, embodiments detecting and correcting load imbalance on power supply phases within a managed scope using a software controlled power switch matrix that is resident in each power distribution unit supplying power in the managed scope. Managed scope could include a plurality of power distribution units supplying a plurality of circuit or equipment loads in a plurality of premises. On each PDU, the software controlled switch matrix maintains and changes physical coupling of power supply phases to circuit and equipment loads. Further embodiments include correcting power supply phase load imbalances through software commands to adjust the coupling of power supply phases to circuit or equipment loads. Embodiments are intended to help power administrators maintain power supply phase load balance effectively in a managed scope. Other embodiments are disclosed.