Abstract: An arc fault demonstrator device for testing the efficacy of an arc fault interrupter (AFI) circuit breaker. The device includes a motor that moves a movable electrode relative to a stationary electrode under microprocessor control. A relay switches the electrodes connection between an arc voltage measurement circuit and an electrode close circuit. When current is applied to the electrodes, the measurement circuit provides voltage measurements to the microprocessor, which instructs the motor to move the electrodes closer or apart. When the arc voltage is below a low threshold, the electrodes are moved apart until the arc voltage exceeds a medium threshold. When the arc voltage exceeds a high threshold, the electrodes are moved closer until the arc voltage falls below the medium threshold. A switch switches between the AFI circuit breaker or a conventional circuit breaker to confirm that the AFI breaker will trip upon detection of the arc whereas the conventional breaker will not.

Abstract: A method of detecting an electrical load loss following an electrical power disturbance in a monitored electrical power distribution system comprises (1) determining an expected characteristic of a parameter representing normal operation of an electrical load receiving power from the electrical power distribution system, (2) detecting a disturbance in the monitored electrical power distribution system, and (3) determining whether the load, or power circuit, or a portion of the load or power circuit, was lost as a result of the disturbance, by evaluating an actual characteristic of the parameter after termination of the disturbance with respect to the expected characteristic of said parameter.

Abstract: An energy efficiency solution for automatically pushing data measured by IEDs in a utility system to an Internet server. Before the utility system is commissioned, the manufacturer pre-configures each IED to automatically push measured data to the server at regular intervals and associates each IED with a unique identifier that is transmitted with the data and with a customer who has purchased the solution. After commissioning, the IEDs come online and begin to automatically push their measured data to the server. The customer logs into the website via a manufacturer-provided access code to access the measured data instantly. Requests to change the type of data pushed from IEDs and other configuration changes can be made via the website. Periodically, the IEDs ask whether any configuration updates exist, and if so, the server makes available to the IEDs the updated configuration. By having IEDs initiate communications for data transmission and configuration updates, intervening firewalls are bypassed.

Abstract: A lighting control system is provided for a space that is equipped with multiple lamps for illuminating the space and multiple power circuits for supplying power to different groups of the lamps. The control system stores information relating to the past illumination of the lamps in each of the different groups. The system detects conditions or events that indicate that increased illumination of the space by the lamps is needed, and produces a control signal in response to the detection of a condition or event that indicates that increased illumination of the space by the lamps is needed. In response to the control signal, the system supplies power to at least one of the power circuits, which is selected on the basis of the stored information, to turn ON the group of lamps receiving electrical power from that power circuit.

Abstract: A resistance weld control employing a model-based run-to-run estimate of load impedance, giving the weld control system the ability to maintain and predict the expected impedance of a successfully completed resistance spot weld, and to detect when the load impedance observed by the resistance weld control is within a target neighborhood of that impedance predicted by the model-based run-to-run estimate of load impedance. A target weld current and a range of weld times may be specified, such that the actual weld time employed in making the resistance spot weld is responsive to the time required to complete the contact preparation phase. Further, a fixed weld time and a range of target weld currents may be specified to make a resistance spot weld, such that the actual target weld current employed is responsive to the time required to complete the contact preparation phase of the weld.

Abstract: A high ampacity busbar includes a pair of oppositely facing bowl-shaped conductors, each of whose cross sections resembles half of a hexagon or an open isosceles trapezoid, separated by an air gap in both horizontal and vertical configurations. The air gap increases cooling efficiency by natural convection by exposing more surface area of the conductors directly to the air flow within the electrical distribution equipment cabinet. As a result, the overall temperature of the bus system is reduced. The shaped conductors have smoother transitions presented to the electrical current between the bends of the conductors. These smooth transitions improve current distribution throughout the conductor, reducing skin effects. As a result of improved thermal dissipation and reduced skin effects, the amount of copper needed to maintain the same ampacity is significantly reduced. Magnetic shields can be placed between adjacent busbars, reducing proximity effects.

Abstract: An algorithm for verifying the state of switches (such as in a transfer switch mechanism) and for controlling the switches. The control algorithm controls automatic actuation of the switches. The verification algorithm measures the instantaneous voltage on the source and load sides of one or both switches and calculates the RMS magnitude, period, and relative phase for each voltage measurement. If the voltage characteristics for the load do not match any of those for any source, an error is outputted. If the voltage characteristics of the sources match each other, the algorithm determines that they are synchronized. The algorithm determines which switch is closed by comparing the voltage characteristics of the load and of each source, and if there is a match, then the switch associated with the source that is matched with the load is determined to be closed. Otherwise, the switch is determined to be opened.

Abstract: A method of monitoring the electrical power in multiple branch circuits of an AC electrical power distribution system comprises monitoring at least one voltage common to said multiple branch circuits using a main meter unit, monitoring currents of the multiple branch circuits using multiple current cards that receive a plurality of current inputs from current transducers in the multiple branch circuits, sampling the monitored voltage in the main meter unit and the monitored currents in the current cards multiple times in each cycle of the AC power signal, determining the magnitudes and angles of spectral components of the sampled current in the current cards, sending data representing the magnitudes and angles of at least selected spectral components from the current cards to the main meter unit, and storing the voltage samples and the magnitudes and angles of at least the selected spectral components in the main meter unit.

Abstract: An electrical enclosure system for transferring heat from a closed environment, includes an electrical device having a heat-generating part, and a polymer-based ventless housing for protecting the electrical device from environmental contaminants. The ventless housing fully encloses the electrical device and includes a base layer forming an impact-resistant portion of the ventless housing. The base layer includes one or more open areas in close proximity to the heat-generating part. The ventless housing further includes an integrated thermally conductive layer that forms a heat-flow path for conducting heat away from the heat-generating part towards an exterior environment. The integrated thermally conductive layer is molded around the base layer such that portions of the integrated thermally conductive layer cover the open areas of the base layer.

Abstract: A method of performing a sequence-of-events analysis in a power monitoring system includes the acts of monitoring, receiving, analyzing, and storing. The act of monitoring includes monitoring messages published by multiple power monitors over a peer-to-peer communications network. The messages include electrical power monitoring parameters. The act of receiving includes receiving the published messages in a subscriber intelligent electronic device in the power monitoring system. The act of analyzing includes analyzing at least a portion of the received messages, performing statistical analysis and/or continuously scanning for an event of interest. The act of storing includes storing at least one record including at least one of statistical data or event of interest data.

Abstract: A method of graphically representing values of at least one selected parameter at multiple monitoring points in a utility system, comprises receiving data measured at the multiple monitoring points; determining the values of the selected parameter at the multiple monitoring points, based on the received data, and using the values to generate a graphical representation of the values of the selected parameter at the multiple monitoring points, the graphical representation including shapes having (1) sizes representative of the magnitudes of the values and (2) locations representative of the hierarchy of the monitoring points. In one application, the selected parameter is at least one of electrical power and energy consumed in portions of an electrical power distribution system that correspond to the multiple monitoring points.

Abstract: A method of determining a slip estimate associated with an induction motor through analysis of voltage and current signals. A fundamental frequency is calculated from a representation (e.g., complex representation) of the voltage signal, and a saliency frequency is calculated from a representation of the current signal. An estimation of slip quantity is calculated according to a slip estimation function that includes the saliency frequency, a saliency order, the fundamental frequency, a quantity of rotor slots, and a quantity of poles of the motor.

Abstract: A method and apparatus to provide estimates of electrical parameters for line-connected induction motors during either steady-state or dynamic motor operations. The electrical parameters are calculated from the motor nameplate data and voltage and current measurements. No speed sensors or electronic injection circuits are needed. The method can be divided into 4 major steps. First, complex space vectors are synthesized from voltage and current measurements. Second, the instantaneous rotor speed is detected by calculating the rotational speed of a single rotor slot harmonic component with respect to the rotational speed of the fundamental frequency component. Third, the positive sequence fundamental frequency components are extracted from complex space vectors. Finally, least-squares estimates of the electrical parameters are determined from a dynamic induction motor equivalent circuit model.

Abstract: A method of estimating an instantaneous frequency of a component of interest in a complex primary signal via a complex Phase Locked Loop (PLL). A complex incident signal including a complex exponential evaluated at a synthesis frequency is calculated according to a complex Voltage Controlled Oscillator (VCO) function. A complex mixed signal is calculated according to a function that includes multiplying the complex primary signal by a representation of the complex incident signal. A complex baseband signal is calculated according to a function that includes filtering the complex mixed signal such that the bandwidth of the complex baseband signal is less than or equal to the bandwidth of the complex mixed signal. A residual frequency of the complex baseband signal is calculated via a complex Phase Discriminator (PD). The synthesis frequency is modified according to a function that includes the synthesis frequency and the residual frequency, such that the residual frequency is minimized.

Abstract: A method and apparatus to provide continuous and reliable rotor temperature estimates for line-connected induction motors during steady-state and/or dynamic motor operations. Rotor temperature is calculated from voltage and current measurements without any temperature or speed sensors. First, complex space vectors are synthesized from voltage and current measurements. Second, the instantaneous rotor speed is detected by calculating the rotational speed of a single rotor slot harmonic component with respect to the rotational speed of the fundamental frequency component. Third, the positive sequence fundamental frequency components are extracted from complex space vectors. Fourth, the rotor time constant is estimated in a model-reference adaptive system based on a dynamic induction motor equivalent circuit model. Finally, the rotor temperature is calculated according to the linear relationship between the rotor temperature and the estimated rotor time constant.

Abstract: A method of determining a quantity of rotor slots in an induction motor through analysis of voltage and current signals. An approximate slip is calculated according to an approximate slip function that is independent of a rotor slots quantity. A fundamental frequency is calculated from a representation of the voltage signal. A saliency frequency is calculated from a representation of the current signal. For each rotor slots index in a set of rotor slots indices, a slip estimate is calculated according to a slip estimation function that includes the saliency frequency, a saliency order, the fundamental frequency, a rotor slots index in the set of rotor slots indices, and a quantity of poles of the motor, such that the slip estimate is evaluated at respective ones of the set rotor slots indices. A slip estimation error signal is calculated according to a slip estimation error function that includes a difference between the approximate slip and respective ones of the slip estimates.

Abstract: A communication system is provided for communication within a control system. The communication system has a plurality of simple devices connected to an intra-level communications network, each simple device being adapted to directly exchange data with the other simple devices. The communications system also has at least one intelligent device connected to the intra-level communications network, each intelligent device being adapted to directly exchange data with each simple device on the intra-level communications network. The communication system can have a plurality of intra-level communications networks.

Abstract: Circuit for determining the presence or absence of a remotely controlled circuit beaker connection to a control circuit and the current state of an internal operating device of a remotely controlled circuit breaker connected to a control circuit.

Abstract: An induction motor having a rotor and a stator is protected during running overloads by connecting the motor to an overload protection relay that can be tripped to interrupt power to the motor in the event of an overload, tracking the stator winding temperature of the motor during running overloads with a hybrid thermal model by online adjustment in the hybrid thermal model, and tripping the overload protection relay in response to a predetermined running overload condition represented by the tracked stator winding temperature. In one embodiment of the invention, the stator winding temperature is tracked by use of an online hybrid thermal model that uses the resistance of the rotor as an indicator of rotor temperature and thus of the thermal operating conditions of the motor. The hybrid thermal model incorporates rotor losses and heat transfer between the rotor and the stator, and approximates the thermal characteristics of the rotor and stator.

Abstract: A DC motor mechanical shock protection system monitors the motor current to determine the torque the motor is applying to the gearbox, and takes mitigating action if the torque approaches a level that can damage the driven device and/or the drive system. This protects the system from mechanical shock without limiting the available torque during normal operation. The change in motor current is monitored to detect the inertial torque before the elasticity between the motor and the driven device is fully compressed and the motor mounting or gearbox begin to be damaged.