Abstract: One embodiment describes a method that includes determining, using a control circuitry, temperature of a switching device before a make operation by applying a measurement current to an operating coil of the switching device, wherein the measurement current is insufficient to make the switching device; and determining voltage at the operating coil when the measurement current is applied, in which the voltage at the operating coil is directly related to the temperature. The method further includes determining, using the control circuitry, when to apply a pull-in current to the operating coil to close the switching device based at least in part on the voltage at the operating coil, such that the switching device makes at a desired time.

Abstract: An RM current sensor assembly is used to indirectly sense the service current being drawn from a service by an electrical branch circuit, the output from which can be used to monitor the service current for features indicative of the presence series and/or parallel arc faults are present in the electrical branch circuit as they progress from their incipiency. The RM current sensor assembly is significantly smaller and less costly than prior art current transformers sensing current directly from the service line at full magnitude. The requisite bandwidth for accurately performing extraction of features indicating arc faults is maintained at this low cost and size because the amount of current actually sensed is substantially smaller. Current signature analysis can also be performed to monitor the operational integrity of appliances with motors, and an RM differential current sensor can detect cumulative leakage current to ground in the electrical branch circuit.

Abstract: A ratio metric (RM) approach to providing the current sensing function of service currents to smart metering applications results in an RM current sensor assembly and RM differential current sensor assembly that can replace prior art sensors currently used for this purpose, with substantial reduction in cost of operation and size. The current sensor assemblies leverage current dividers having estimated current ratios, with any error being calibrated out of the sensor assembly by various approaches, such as requiring a single parametric adjustment of a burden resistor value to establish an expected output magnitude for a known current input magnitude to a requisite degree of accuracy. Calibration profiles for the entire service current range can be generated and used with the current sensor assemblies. Multiple RM current sensor assemblies can be used for segments of the current range to further increase accuracy. Improved and low cost leakage current protection is provided.

Abstract: One embodiment describes a tangible, non-transitory, computer-readable medium storing instructions executable by a processor in a control circuitry. The instructions include instructions to receive an instruction to make a switching device; determine, using the control circuitry, a voltage waveform of a power source; determine, using the control circuitry, a desired time to make the switching device based at least in part on the source voltage waveform; determine, using the control circuitry, an expected make time of the switching device; and determine, using the control circuitry, when to apply a pull-in current to make the switching device at the desired time based at least in part on the expected make time and the desired time to make.

Abstract: One embodiment describes a three-phase electromechanical switching device, which includes three single-phase switching devices mechanically and electrically coupled in parallel with one another. Each of the single-phase switching devices includes a direct current electromagnetic operator that receives a direct current control signal from control circuitry, in which the direct current control signal instructs the single phase switching device to open or close a single current carrying path in the single phase switching device at a desired time; stationary contacts disposed in a device housing; and a movable assembly that is displaced by energizing or de-energizing the electromagnetic operator, in which the movable assembly includes movable contacts that, with the stationary contacts, open and close the single current carrying path.

Abstract: One embodiment describes a switching device system, which includes a first single pole switching device that selectively connects and disconnects a first phase of electric power to a first winding of a three phase motor; a second single switching device that selectively connects and disconnects a second phase of electric power to a second winding of the three phase motor; in which the first and second single pole switching devices control temperature of the motor by, at a first time, connecting the first phase and the second phase electric power to the motor.

Abstract: A method and apparatus using electromagnetic switching in a two-step connection process is provided to minimize surge currents and torque oscillations in three-phase motors during starts.

Abstract: A test circuit performs fault detection tests on a motor branch circuit, to detect pre-existing faults before a motor start-up to pre-empt potential damage to the motor branch circuit therefrom. The test circuit is configured to be coupled to the phase lines of a motor branch circuit at a set of test points strategically located on the phase lines. The test circuit includes test lines that are each coupled to a different one of the phase lines at one of the set of test points. The test circuit includes a test controller that, during a test mode, sequentially presents a low voltage supply to each phase line through the test line coupled thereto, to test for ground faults then sequentially couples the low voltage supply across each possible pairing of the phase lines to test for line-to-line faults. The test mode can be initiated manually or automatically.

Abstract: One embodiment describes a method that includes determining, using a control circuitry, temperature of a switching device before a make operation by applying a measurement current to an operating coil of the switching device, wherein the measurement current is insufficient to make the switching device; and determining voltage at the operating coil when the measurement current is applied, in which the voltage at the operating coil is directly related to the temperature. The method further includes determining, using the control circuitry, when to apply a pull-in current to the operating coil to close the switching device based at least in part on the voltage at the operating coil, such that the switching device makes at a desired time.

Abstract: One embodiment describes a tangible, non-transitory, computer-readable medium storing instructions executable by a processor of an operating coil driver circuitry. The instructions include instructions to instruct a switch to supply a specific current to an operating coil of a switching device using a pulse-width modulated signal; determine duty cycle of the pulse-width modulated signal; and determine wellness of the switching device based at least in part on the duty cycle of the pulse-width module signal.

Abstract: A test circuit performs fault detection tests on a motor branch circuit, to detect pre-existing faults before a motor start-up to pre-empt potential damage to the motor branch circuit therefrom. The test circuit is configured to be coupled to the phase lines of a motor branch circuit at a set of test points strategically located on the phase lines. The test circuit includes test lines that are each coupled to a different one of the phase lines at one of the set of test points. The test circuit includes a test controller that, during a test mode, sequentially presents a low voltage supply to each phase line through the test line coupled thereto, to test for ground faults then sequentially couples the low voltage supply across each possible pairing of the phase lines to test for line-to-line faults. The test mode can be initiated manually or automatically.

Abstract: One embodiment describes a method that includes in a first switching operation of an electrical power switching system including three separately controllable single pole, single current-carrying path switching devices that provide three-phase power to a load, and control circuitry coupled to the switching devices to control closing and opening of the current-carrying paths, commanding at least one of the switching devices to open or close in advance of at least one other of the switching devices based upon a current zero-crossing or a predicted current zero-crossing of input three-phase power; and in subsequent switching operations alternating which of the three switching devices is closed or opened in advance of another of the switching devices.

Abstract: One embodiment describes a method that includes determining, using a control circuitry, temperature of a switching device before a make operation by applying a measurement current to an operating coil of the switching device, wherein the measurement current is insufficient to make the switching device; and determining voltage at the operating coil when the measurement current is applied, in which the voltage at the operating coil is directly related to the temperature. The method further includes determining, using the control circuitry, when to apply a pull-in current to the operating coil to close the switching device based at least in part on the voltage at the operating coil, such that the switching device makes at a desired time.

Abstract: An electronic overload relay leverages a ratio metric current design to permit size and cost optimized circuit components that can be used to sense current for purposes of protecting motors by detecting overcurrent conditions in branch motor applications in lieu of thermal overload devices. A current divider is used to significantly reduce the current that must be sensed by a magnetically coupled toroid to permit its components to be size and cost optimized and to be implemented easily on a printed circuit board. The DC resistance can be used to provide a coarse design that can be calibrated pre-manufacture to establish the accuracy required in sensing motor load current by adjusting the value of the burden resistor. Precision printed circuit board traces can be used to ensure repeatability during manufacturing. A sweepable trigger value generator can permit operation over the entire range of FLC and the threshold can be calibrated into the device.

Abstract: One embodiment describes an operating coil driver circuitry, which includes a control circuitry that outputs a trigger signal and a reference voltage; an operational amplifier that compares the reference voltage to a node voltage, in which the node voltage is directly related to current flowing through an operating coil of a switching device and the operational amplifier outputs a logic high signal when the node voltage is higher than the reference voltage and outputs a logic low signal when the node voltage is lower than the reference voltage; and a flip-flop that outputs a pulse-width modulated signal to instruct a switch to supply a desired current to the operating coil based at least in part on the trigger signal and the signal output by the operational amplifier.

Abstract: One embodiment describes an interlock for an electromechanical switching system, which includes a housing; a first camming lockout member disposed in the housing and that contacts an auxiliary operator of a first electromechanical switching device; a second camming lockout member disposed in the housing and that contacts an auxiliary operator of a second electromechanical switching device, which the first camming lockout members contacts the second camming lockout member when the first camming lockout member is moved to an actuated position by the first electromechanical switching device to prevent movement of the second camming lockout member to an actuated position.

Abstract: One embodiment describes a switching device system, which includes a first single pole switching device that selectively connects and disconnects a first phase of electric power to a first winding of a three phase motor; a second single switching device that selectively connects and disconnects a second phase of electric power to a second winding of the three phase motor; in which the first and second single pole switching devices control temperature of the motor by, at a first time, connecting the first phase and the second phase electric power to the motor.

Abstract: A method and apparatus using electromagnetic switching in a two-step connection process is provided to minimize surge currents and torque oscillations in three-phase motors during starts.

Abstract: A test circuit performs fault detection tests on a motor branch circuit, to detect pre-existing faults before a motor start-up to pre-empt potential damage to the motor branch circuit therefrom. The test circuit is configured to be coupled to the phase lines of a motor branch circuit at a set of test points strategically located on the phase lines. The test circuit includes test lines that are each coupled to a different one of the phase lines at one of the set of test points. The test circuit includes a test controller that, during a test mode, sequentially presents a low voltage supply to each phase line through the test line coupled thereto, to test for ground faults then sequentially couples the low voltage supply across each possible pairing of the phase lines to test for line-to-line faults. The test mode can be initiated manually or automatically.

Abstract: One embodiment describes a method that includes determining a desired torque level of a motor actuated by a motor starter; determining, using a control system, a configuration of the motor starter to achieve the desired torque level, in which determining the configuration includes determining which of a plurality of switching devices in the motor starter should be opened and which should be closed; and instructing, using the control system, the motor starter to implement the determined configuration by opening or closing one or more of the plurality of switching devices.