Non-contact current-sensing and voltage-sensing clamp
First Claim
1. A sensor for sensing an electric potential on a wire of a power distribution system and a current passing through the wire, the sensor comprising:
- a sensor clamp body including a pair of handles disposed at a proximal end thereof and a hinge mechanism coupling the pair of handles, so that compressing the pair of handles opens an aperture at a distal end of the sensor clamp body for receiving the wire, and wherein the hinge mechanism includes a restoring spring to close the aperture around the wire when the pair of handles is released;
a current-sensing device disposed within the sensor clamp body for providing a first output indicative of the current passing through the wire;
a voltage-sensing device integrated in the sensor clamp body for providing a second output indicative of the electric potential on the wire, wherein the voltage-sensing device and the current-sensing device do not make electrical contact with the wire, wherein the voltage-sensing device has a first terminal for providing the second output and a second terminal; and
a selector circuit coupled to the voltage-sensing device for selecting between a measurement mode and a calibration mode, wherein in the calibration mode, the selector circuit couples the first terminal and the second terminal of the voltage-sensing device to a current source that causes a calibration current of predetermined magnitude to be conducted through the voltage-sensing device and to a current-measuring circuit that measures the first output of the current-sensing device to obtain a current measurement calibration value when the selector circuit selects the calibration mode, and wherein when the selector circuit selects the measurement mode, the current-measuring circuit adjusts a value of the first output in conformity with the current measurement calibration value.
1 Assignment
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Accused Products
Abstract
A clamping current and voltage sensor provides an isolated and convenient technique for measuring current passing through a conductor such as an AC branch circuit wire, as well as providing an indication of an electrostatic potential on the wire, which can be used to indicate the phase of the voltage on the wire, and optionally a magnitude of the voltage. The device includes a body formed from two handle portions that contain the current and voltage sensors within an aperture at the distal end, which may be a ferrite cylinder with a hall effect sensor disposed in a gap along the circumference to measure current, or alternatively a winding provided through the cylinder along its axis and a capacitive plate or wire disposed adjacent to, or within, the ferrite cylinder to provide the indication of the voltage. When the handles are compressed the aperture is opened to permit insertion of a wire for measurement.
82 Citations
17 Claims
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1. A sensor for sensing an electric potential on a wire of a power distribution system and a current passing through the wire, the sensor comprising:
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a sensor clamp body including a pair of handles disposed at a proximal end thereof and a hinge mechanism coupling the pair of handles, so that compressing the pair of handles opens an aperture at a distal end of the sensor clamp body for receiving the wire, and wherein the hinge mechanism includes a restoring spring to close the aperture around the wire when the pair of handles is released; a current-sensing device disposed within the sensor clamp body for providing a first output indicative of the current passing through the wire; a voltage-sensing device integrated in the sensor clamp body for providing a second output indicative of the electric potential on the wire, wherein the voltage-sensing device and the current-sensing device do not make electrical contact with the wire, wherein the voltage-sensing device has a first terminal for providing the second output and a second terminal; and a selector circuit coupled to the voltage-sensing device for selecting between a measurement mode and a calibration mode, wherein in the calibration mode, the selector circuit couples the first terminal and the second terminal of the voltage-sensing device to a current source that causes a calibration current of predetermined magnitude to be conducted through the voltage-sensing device and to a current-measuring circuit that measures the first output of the current-sensing device to obtain a current measurement calibration value when the selector circuit selects the calibration mode, and wherein when the selector circuit selects the measurement mode, the current-measuring circuit adjusts a value of the first output in conformity with the current measurement calibration value. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A sensor for sensing an electric potential on a wire of a power distribution system and a current passing through the wire, the sensor comprising:
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a sensor clamp body including a pair of handles disposed at a proximal end thereof and a hinge mechanism coupling the pair of handles, so that compressing the pair of handles opens an aperture at a distal end of the sensor clamp body for receiving the wire, and wherein the hinge mechanism includes a restoring spring to close the aperture around the wire when the pair of handles is released; a current-sensing device disposed within the aperture and comprising at least one ferrite cylinder portion disposed within the aperture and a semiconductor magnetic field sensor disposed within a gap formed between ends of the at least one ferrite cylinder portion; a voltage-sensing device integrated in the sensor clamp body and comprising a metal layer deposited on or affixed to at least one of the ferrite cylinder portions, wherein the voltage-sensing device has a first terminal for providing the second output and a second terminal; and a selector circuit coupled to the voltage-sensing device for selecting between a measurement mode and a calibration mode, wherein in the calibration mode, the selector circuit couples the first terminal and the second terminal of the voltage-sensing device to a current source that causes a calibration current of predetermined magnitude to be conducted through the voltage-sensing device and to a current-measuring circuit that measures the first output of the current-sensing device to obtain a current measurement calibration value when the selector circuit selects the calibration mode, and wherein when the selector circuit selects the measurement mode, the current-measuring circuit adjusts a value of the first output in conformity with the current measurement calibration value. - View Dependent Claims (10)
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11. A method for sensing an electric potential on a wire of a power distribution system and a current passing through the wire, the sensor comprising:
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securing a clamp body of a sensor around the wire by compressing and releasing a pair of handles disposed at a proximal end of the clamp body to open and close an aperture formed at a distal end of the sensor clamp body, wherein the aperture receives the wire; generating a first indication of the current passing through the wire by measuring a magnitude of magnetic flux through the aperture by a current-sensing device disposed within the clamp body; generating a second indication of the electric potential of the wire by electrostatically coupling the wire to a voltage-sensing device disposed within the aperture proximate the wire; selecting between a calibration mode and a measurement mode in a circuit connected to the current-sensing device; responsive to selecting the measurement mode, first measuring a first magnitude of a first magnetic field generated by current conducted in the wire using an output of the current-sensing device; responsive to selecting the measurement mode, second measuring at least one of a second magnitude or phase of an electrostatic field generated by the wire by measuring a voltage of the voltage-sensing device; responsive to selecting the calibration mode, conducting a calibration current of predetermined magnitude through the voltage-sensing device and third measuring a second magnitude of a second magnetic field generated by the predetermined current in the voltage-sensing device using the output of the sensing element to obtain a current measurement calibration value; and correcting a result of the first measuring in conformity with the current measurement calibration value. - View Dependent Claims (12, 13, 14, 15, 16, 17)
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Specification