Abstract: Arcing faults in dc electric power systems are detected by apparatus which responds to a predetermined drop either in voltage across, or current drawn by, a dc load. The voltage and current drops can be measured values or scaled to the source voltage. In another arrangement, the load current is interrupted momentarily when a step decrease in current is detected. If the dc current does not return, within a predetermined margin, to the decreased value before interruption, arcing is indicated. In a third embodiment, drift of the load current following detection of a step decrease, either upward toward a short or downward toward an open circuit, is taken as an indication of arcing.

Abstract: Upon initiation of operation of a contactor from an unactuated condition to an actuated condition, the maximum magnitude of an initial current conducted to the coil of the contactor is determined. Once the contactor has been operated to the closed condition, the holding current is checked to determine if it exceeds a reference current. The reference current is a predetermined function of the maximum initial current. If the reference current is less than the holding current, a malfunction signal is provided. In another embodiment of the invention, a sensor is provided to sense the position of movable contacts connected with an armature of the contactor.

Abstract: A varying voltage is applied across a coil of a contactor. The varying voltage has a characteristic (frequency) which varies as a function of the position of the armature. The varying voltage is transmitted to a coupler which transmits information to a controller. The coupler may include one or more light sources (LEDs) which are sequentially energized and de-energized to sequentially render a phototransistor conducting and nonconducting. The frequency of the output from the coupler corresponds to the frequency at which the phototransistor is changed between the conducting and nonconducting conditions. A controller determines whether the frequency of the output from the coupler corresponds to the intended position of the armature of the contactor or to an unintended position by comparing the frequency of the output from the coupler to known frequencies for various positions of the armature.

Abstract: A solenoid operated proportional control expansion valve having a tubular armature guide of non-magnetic material disposed externally of the valve blocks with a magnetic pole piece welded on the end of the tubular guide. A plastic encapsulated coil is received over the guide. The armature guide has a flange therein which in one embodiment is welded to a second flanged tube threaded into the valve blocks. In other embodiments the guide flange is directly mechanically fastened to the valve block. A cup-shaped pole frame is received over the coil for completing the magnetic flux loop about the coil.

Abstract: A method and system for controlling an electromechanical actuator assembly and measurement of actuator position via two drive wires to the actuator assembly. The system includes sensing the changing inductance of the actuator through the electrical drive line and associating the sensed inductance with a corresponding position of the actuating member.

Abstract: In an electric circuit supplying AC line current to a load (30, 31) from an AC source (26) of given frequency providing repetitive cycles, arc detection is provided by sensing cycle to cycle changes in the AC line current. The AC line current is sampled with a harmonic notch filter (72) at a plurality of n phases .THETA..sub.1 through .THETA..sub.n during each of a plurality of m cycles of the AC source (26), to provide a plurality of currents I.sub.n,m, where n is the phase and m is the cycle. The differences (I.sub.n,m)-(I.sub.n,m-x), where x is a designated number of cycles, provide a plurality of current difference signals. The absolute values of these current difference signals ID are accumulated in a synchronous summer (94) over the m cycles. An arc indicative signal is generated in response to given conditions and given combinations of conditions (116) of the cumulative absolute current difference signals ID.

Abstract: In an electric circuit supplying AC line current rent to a load (30, 31) from an AC source (26) of given frequency providing repetitive cycles, arc detection is provided by sensing cycle to cycle changes in the AC line current. The AC line current is sampled with a harmonic notch filter (72) at a plurality of n phases .THETA..sub.1 through .THETA..sub.n during each of a plurality of m cycles of the AC source (26), to provide a plurality of currents I.sub.n,m, where n is the phase and m is the cycle. The differences (I.sub.n,m)-(I.sub.n,m-x), where x is a designated number of cycles, provide a plurality of current difference signals. The absolute values of these current difference signals ID are accumulated in a synchronous summer (94) over the m cycles. An arc indicative signal is generated in response to given conditions and given combinations of conditions (116) of the cumulative absolute current difference signals ID.

Abstract: A current transformer device is formed on a ceramic substrate which is provided with a plurality of planar conductive tracks formed on a surface of the substrate where the conductive tracks extend substantially radially from an imaginary point on the surface of the substrate. A structure of permeable material layers is then tape cast or epitaxially formed by vapor deposition of a thick film of magnetic ceramic over the major portion of each of the conductive tracks to form a permeable toroidal core. A lead frame is then placed over the core and a plurality of metal conductors are soldered to each of the respective exposed ends of the metal conductive tracks on the substrate to form a toroidal coil surrounding the toroidal core. The required electrical elements to complete the current transformer device are mounted to a second side of the ceramic substrate and electrically connected to the toroidal coil for powering and/or receiving signals therefrom.

Abstract: A current transformer device is formed on a ceramic substrate which is provided with a plurality of planar conductive tracks formed on a surface of the substrate where the conductive tracks extend substantially radially from an imaginary point on the surface of the substrate. A structure of permeable material is then tape cast or epitaxially formed by vapor deposition of a thick film of magnetic ceramic over the major portion of each of the conductive tracks to form a permeable toroidal core. A lead frame is then placed over the core and a plurality of metal conductors are soldered to each of the respective exposed ends of the metal conductive tracks on the substrate. The required electrical elements to complete the current transformer device are mounted to a second side of the ceramic substrate and electrically connected to the toroidal coil for powering and/or receiving signals therefrom.

Abstract: An arc detection method and apparatus is provided for an electric circuit having an electrified conductor (46) connecting a voltage source (26) to a load (30). The arc detector includes a field sensor (62) sensing an electromagnetic field established about the conductor by the occurrence of an electrical arc in the circuit, and generating a field responsive signal in response thereto. Arc discrimination circuitry responds to the field sensor and generates a tentative arc signal in response to a given characteristic of the field responsive signal. Arc timing window circuitry responds to the arc discrimination circuitry and generates a confirmed arc signal in response to a given timing characteristic of the tentative arc signal.

Abstract: An arc detector antenna transducer (62) for an electric circuit has an electrified conductor (46) connecting a voltage source (26) to a load (30). The arc detector transducer includes an E field sensor (66) sensing the E field established about the conductor by the occurrence of an electrical arc in the circuit, and a B field sensor (68) sensing the B field established about the conductor by the occurrence of the electrical arc in the circuit.

Abstract: An arc detection method and apparatus is provided for an electric circuit having an electrified conductor (46) connecting a voltage source (26) to a load (30). A field sensor senses an electromagnetic field established about the conductor by the occurrence of an electrical arc in the circuit, and generates a field responsive signal. Arc discrimination circuitry includes frequency responsive circuitry responding to the field sensor and generating an arc indicative signal in response to a given frequency characteristic of the field responsive signal. The frequency responsive circuitry monitors a plurality of different frequencies of the field responsive signal, and generates the arc indicative signal in response to a given combination of field responsive signal frequencies. A comb filter passes the field responsive signal through a plurality of passbands, and the arc indicative signal is generated in response to a given frequency signature of the field responsive signal.

Abstract: An arc detection method and apparatus is provided for an electric circuit having an electrified conductor (46) connecting a voltage source (26) to a load (30). The system senses the electromagnetic field established about the conductor by the occurrence of an electrical arc in the electric circuit, and generates a field responsive signal. Arc discrimination circuitry responding to the field responsive signal and generates an arc indicative signal in response to a given characteristic of the field responsive signal. The system includes an E field sensor (66) and a B field sensor (68).

Abstract: An arc detection method and apparatus is provided for an electric circuit having an electrified conductor (46) connecting a voltage source (26) to a load (30). The arc detector includes a field sensor (62) sensing an electromagnetic field established about the conductor by the occurrence of an electrical arc in the electric circuit, and generating a field responsive signal in response thereto. Arc discrimination circuitry responds to the field sensor and generates an arc indicative signal in response to a random chaotic pattern of the field responsive signal.

Abstract: An arc detection method and apparatus is provided for an electric circuit having an electrified conductor (46) connecting a voltage source (26) to a load (30), the conductor having a line side extending from the arc detector to the voltage source, and a load side extending from the arc detector to the load. The arc detector includes a field sensor (62) sensing the electromagnetic field established about the conductor by the occurrence of an electrical arc in the circuit, and generating a field responsive signal in response thereto. Direction sensing circuitry detects whether the arc is from the load side or the line side, and generates a direction indicative signal.

Abstract: The present invention is a current sensor employing a magneto resistive sensor having high fidelity of output. This current sensor includes a magnetic flux concentrator substantially encircling the electrical conductor having magnetic sensing, a magnetic device generating a magnetic field component along an axis offset from the principle axis, a magneto resistive device disposed in the magnetic sensing region, a constant current source supplying a predetermined constant current to said magneto resistive device, and a voltage sensing circuit connected to said magneto resistive device for measuring resistance by measuring a difference voltage induced by said constant current. This measured voltage corresponds to the current through the conductor. The magneto resistive device is formed as a Wheatstone bridge having a first and second pair of opposite terminals.