Cooper Technologies Company

Mcgraw-edison Company

Timothy Robert Day

Aaron Kalyuzhny

John C McCall

Veselin Skendzic

Ljubomir A Kojovic

Martin T Bishop

Eric Arden Lee

Daniel Patrick Roth

Martin P Bishop

Device protection using temperature compensation. A logic module associated with groups of capacitors adjusts complex impedance planes associated with the capacitor groups to account for ambient temperature variations. In particular, the logic module is configured to adjust a center of a circle of each complex impedance plane based on an average impedance. The average impedance for a selected capacitor group includes impedance measurements for groups other than the selected group, to prevent capacitor failures in that group from skewing the average. The logic module can adjust the circle center in response to changes in average impedance over periods of time. For example, the logic module can filter measured differences in average impedance using a low pass filter, to distinguish slow impedance changes caused by temperature variations and rapid impedance changes caused by capacitor failures. The logic module can adjust the circle center in accordance with the filtered difference value.

Device protection using temperature compensation

A control system for an electrical power system includes an electrical corrective device, a voltage measuring device coupled to each phase of the electric power system, a current measuring device connected between each phase of the electric power system and the electrical corrective device, and a protective device connected to outputs of the voltage measuring device and the current measuring device. The protective device includes a controller configured to detect an imbalance using the measured voltages and currents output from the voltage measuring device and the current measuring device without using or independently of other recent voltage or current measurements for other points in the electrical corrective device and independently of a neutral-ground measurement at the electrical corrective device.

Corrective device protection

A differential protection system for power transformers using Rogowski coils as current sensors can support an inrush current detection method based on sensing lows in the derivative of the sensed current. Effective detection of power transformer inrush conditions can enable blocking of a protection relay during inrush where the differential current may exceed a differential threshold value indicative of a fault without the presence of an actual fault. The outputs of the Rogowski coils, being proportional to the first time derivative of the sensed current, may be useful in the inrush detection method. Also, with reduced saturation concerns, the Rogowski coil protection system may employ a single slope response with increased sensitivity. A discrete time sampling technique for identifying low di/dt portions within the sensed current also may be useful in detecting power transformer inrush conditions.

Transformer inrush current detector

Protection systems for electrical systems such as substation power dividers are described. The protection systems may be designed and used to detect and clear faults that may occur within the substation power dividers. For example, a first Rogowski coil may be used to detect current along a primary conductor, and output a corresponding current signal to a multi-function, differential relay having multiple voltage and current inputs. Similarly, additional Rogowski coils may be used at each of a plurality of secondary feeders, where power from the primary feeder may be distributed to the secondary feeders using a connection bus. By comparing the signals from the first Rogowski coil and the additional Rogowski coils, the differential relay may determine whether a fault exists at some point along the conductor(s) and between the first Rogowski coils and the additional Rogowski coils, including whether a fault is associated with the connection bus. Further, the relay may then, in response to the fault, trip a circuit breaker or other network protection device, so that the fault may be corrected.

Electrical protection system

Memory sharing techniques include providing a first device and one or more additional devices. Each device has a memory and is configured to be connected to a network. A portion of the first device memory is allocated, and may be divided into two or more first device memory segments. Each first device memory segment corresponds to a device, and at least one of the first device memory segments corresponds to an additional device. A portion of the additional device memory is allocated, and may be divided into two or more additional device memory segments. Each additional device memory segment corresponds to a device, and at least one additional device memory segment corresponds to the first device. A first device data segment is provided to the additional device, and a first device data validity indication is derived at the additional device. The first device data validity indication is associated with the first device data segment, and the additional device memory segment corresponding to the first device is updated based on the association.

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Racine, WI, United States of America

Timothy Robert Day