Abstract: A system for current sensing includes a first Hall effect sensor and a second Hall effect sensor constructed to provide feedback indicating current flow through a conductor susceptible to external magnetic flux. A housing is configured to position the first Hall effect sensor and the second Hall effect sensor about the conductor to provide generally magnitude equal feedback of the current flow through the conductor and generally polarity opposite feedback of the external magnetic flux.

Abstract: The present invention is directed to a system for current sensing including a first Hall effect sensor and a second Hall effect sensor constructed to provide feedback indicating current flow through a conductor susceptible to external magnetic flux. A housing is configured to position the first Hall effect sensor and the second Hall effect sensor about the conductor to provide generally magnitude equal feedback of the current flow through the conductor and generally polarity opposite feedback of the external magnetic flux.

Abstract: An arc fault detector analyzes patterns in a sequence of counts of interval to interval increases or decreases in integrated current for patterns characteristic of arc faults. In AC systems, the interval can be a full cycle or in an alternative embodiment, the changes in integrated current for positive and negative half cycles are separately determined and then interleaved before the change counts are calculated. The count sequence is reset when patterns characteristic of phenomena other than an arc fault are detected to avoid nuisance trips.

Abstract: The present invention is directed to system for current sensing including a first Hall effect sensor and a second Hall effect sensor constructed to provide feedback indicating current flow through a conductor susceptible to external magnetic flux. A housing is configured to position the first Hall effect sensor and the second Hall effect sensor about the conductor to provide generally magnitude equal feedback of the current flow through the conductor and generally polarity opposite feedback of the external magnetic flux.

Abstract: Electrical equipment (14) is safeguarded from damage due to parallel arc faults by a circuit that provides several levels of protection. A semiconductor switch (18) and a current sensor (24) are placed in series with the electrical equipment (14). When the current to the equipment exceeds a first threshold for a predefined period of time, the semiconductor switch (18) is rendered non-conductive until the circuit is specifically reset. When the current to the equipment exceeds a greater second threshold, a pulsed signal alternately places the semiconductor switch (18) in conductive and non-conductive states so that the average current applied to the equipment (14) is within an acceptable level. The pulses are measured to determine whether a parallel arc fault has occurred. When the measured pulses (74) are within a predetermined range, a parallel arc fault is declared and the semiconductor switch (18) is rendered non-conductive.

Abstract: Torque in a torsion member, such as a rotating shaft, is sensed by a piezoelectric element that is attached to the torsion member. The piezoelectric element has a resonant frequency that varies with changes in the torque and is part of a transducer oscillator that produces a first signal. A reference oscillator has a similar piezoelectric element and produces a second signal having a frequency that varies in response to environmental parameters. The first and second signals are heterodyned, thereby cancelling the effects due to environmental parameters acting on both piezoelectric elements and producing a resultant signal that has a frequency which corresponds to the torque applied to the torsion member.

Abstract: Electrical equipment (14) is safeguarded from damage due to parallel arc faults by a circuit that provides several levels of protection. A semiconductor switch (18) and a current sensor (24) are placed in series with the electrical equipment (14). When the current to the equipment exceeds a first threshold for a predefined period of time, the semiconductor switch (18) is rendered non-conductive until the circuit is specifically reset. When the current to the equipment exceeds a greater second threshold, a pulsed signal alternately places the semiconductor switch (18) in conductive and non-conductive states so that the average current applied to the equipment (14) is within an acceptable level. The pulses are measured to determine whether a parallel arc fault has occurred. When the measured pulses (74) are within a predetermined range, a parallel arc fault is declared and the semiconductor switch (18) is rendered non-conductive.

Abstract: Torque in a torsion member, such as a rotating shaft, is sensed by a piezoelectric element that is attached to the torsion member. The piezoelectric element has a resonant frequency that varies with changes in the torque and is part of a transducer oscillator that produces a first signal. A reference oscillator has a similar piezoelectric element and produces a second signal having a frequency that varies in response to environmental parameters. The first and second signals are heterodyned, thereby cancelling the effects due to environmental parameters acting on both piezoelectric elements and producing a resultant signal that has a frequency which corresponds to the torque applied to the torsion member.

Abstract: A method of manufacturing a piezoelectric torque transducer is provided, comprising the steps of (a) forming a prepared area on a surface of a torsion member adapted to be strained by an applied torque; (b) providing a piezoelectric element having an axis of maximum strain sensitivity and disposing first and second electrodes on opposite faces of the element, respectively, and attaching an electrical lead to each electrode; (c) connecting electrical leads to the electrodes; and (d) disposing the element on the prepared area and orienting the axis of maximum strain sensitivity on the member and securing the element to the prepared area with a material selected from a group consisting of (i) adhesive material and (ii) potting material.

Abstract: A combination fluid condition monitor and fluid level sensor having an excitation electrode divided into two segments disposed closely spaced and parallel to current sensing electrode. For the fluid condition monitoring mode function both segments of the excitation electrode are commonly excited sequentially at high and low frequencies and the currents sensed in the sensing electrode employed to compute the difference in impedance for determining the fluid condition. For the level sensing mode function a mode switching circuit grounds one of the excitation electrode segments and excites the other then grounds the other segment and excites the one segment and the resultant currents ratioed to determine the amount of electrode immersed in fluid and hence the fluid level.

Abstract: Electrical equipment is safeguarded from damage due to faults by a circuit that provides several levels of protection. A semiconductor switch and a current sensor are placed in series with the electrical equipment. When the current to the equipment exceeds a first threshold for a predefined period of time, the semiconductor switch is rendered non-conductive until the circuit is specifically reset. When the current to the equipment exceeds a greater second threshold, a pulsed signal alternately places the semiconductor switch in conductive and non-conductive states so that the average current applied to the equipment is within an acceptable level. Should the current exceed an even greater third threshold, the semiconductor switch is immediately rendered non-conductive until the circuit is manually reset.

Abstract: A sonic back-up proximity sensor employs a first sonic transducer and a second sonic transducer mounted on a rearward portion of a riding lawn mower to create three discrete zones of protection. The first sonic transducer has an associated first region of coverage, or sector, and the second sonic transducer has an associated second sector. The first sonic transducer and second sonic transducer are directed toward one another such that the first sector and second sector at least partially overlap. The overlapping portion of the first sector and second sector provides redundant coverage in an area directly behind the lawn mower. The non-overlapping portion of the first sector defines a second protection zone on one side of the lawn mower. The non-overlapping portion of the second sector defines a third protection zone on a second side of the lawn mower.

Abstract: A protection sensor for a lawn vehicle includes a substantially unidirectional antenna operatively coupled to a Doppler detection circuit. The Doppler detection circuit generates a radio frequency signal which is radiated by the antenna. When the radiated signal strikes an object, such as a person, animal or another moving lawn vehicle, within a predefined detection region of the sensor, the signal is reflected and received by the antenna. The Doppler detection circuit generates an output signal responsive to a difference in frequency between the radiated signal and the reflected signal, thereby indicating the presence of the moving object within the protection region of the sensor. The unidirectional antenna virtually eliminates false detections generated by the lawn vehicle, to which the sensor is mounted, or by the operator of the vehicle.