A voltage detecting device detects a differential voltage between two input nodes having a non-zero common mode voltage. A differential voltage detecting circuit 5 detects the differential voltage by sampling each voltage of the input nodes and outputs a detection voltage indicating a detection result. A leak canceling circuit generates a compensating current, which flows in opposition to a leak current flowing out from the input nodes in correspondence to an operation of the differential voltage detecting circuit. An operation control part controls the leak canceling circuit to perform or stop a canceling operation. A failure diagnosing part performs a failure diagnosis about the leak canceling circuit based on a first detection value and a second detection value of the detection voltages, which are detected during periods when the leak canceling circuit performs and stops the canceling operation.

A fiber optic sensor for measuring voltage in direct current and alternating current systems is disclosed. The sensor may include an optical fiber probe containing transmitting and receiving fibers, fixed conductor elements, and a dynamic conductor element with a reflective surface or material. The reflector may be attached to a dynamic conductor. The two fixed conductors may be placed parallel to one another and coupled to a static voltage source. The dynamic conductor may bisect the fixed conductors and be coupled to a voltage source. The dynamic conductor may be spaced apart from the ends of the fibers in the fiber probe, and positioned so that light transmitted through the transmitting fiber is reflected by that surface into a receiving fiber. A light sensing means may be coupled to the receiving fiber, so light from a light reflected by the reflector body back into the receiving fibers is detected.

A method for detecting an electrical current longitudinal variation in a power transmission system including a power cable. Electric losses and their location along the cable length can be detected. Current variation in a grounded metallic layer of a power cable is measured from Faraday rotation of polarised light travelling in a single-mode optical fiber wound in a radially external position with respect to the grounded metallic layer. Measurements of the Faraday rotation are carried out by means of polarization-sensitive optical time domain reflectometry (POTDR) or by polarization-sensitive optical frequency domain reflectometry (POFDR) while a direct current is injected in the metallic layer.

A voltage detecting device detects a differential voltage between two input nodes having a non-zero common mode voltage. A differential voltage detecting circuit 5 detects the differential voltage by sampling each voltage of the input nodes and outputs a detection voltage indicating a detection result. A leak canceling circuit generates a compensating current, which flows in opposition to a leak current flowing out from the input nodes in correspondence to an operation of the differential voltage detecting circuit. An operation control part controls the leak canceling circuit to perform or stop a canceling operation. A failure diagnosing part performs a failure diagnosis about the leak canceling circuit based on a first detection value and a second detection value of the detection voltages, which are detected during periods when the leak canceling circuit performs and stops the canceling operation.

A voltage detecting device detects a differential voltage between two input nodes having a non-zero common mode voltage. A differential voltage detecting circuit 5 detects the differential voltage by sampling each voltage of the input nodes and outputs a detection voltage indicating a detection result. A leak canceling circuit generates a compensating current, which flows in opposition to a leak current flowing out from the input nodes in correspondence to an operation of the differential voltage detecting circuit. An operation control part controls the leak canceling circuit to perform or stop a canceling operation. A failure diagnosing part performs a failure diagnosis about the leak canceling circuit based on a first detection value and a second detection value of the detection voltages, which are detected during periods when the leak canceling circuit performs and stops the canceling operation.

A method is presented for measuring the electric field of electromagnetic radiation using the spectroscopic responses of Rydberg atoms to the electromagnetic radiation field. The method entails implementing quantitative models of the Rydberg atom response to the electromagnetic radiation field to provide predetermined atomic properties or spectra for field amplitudes and or frequencies of interest, spectroscopically measuring the response (spectrum) of Rydberg atoms exposed to an unknown electromagnetic radiation field, and obtaining the electric field amplitude and/or frequency of the unknown electromagnetic radiation by using features extracted from the measured spectrum and comparing them to features in a predetermined spectrum among the set of predetermined spectra.

An optical sensor that senses current by directing polarized light across an airgap that is orthogonal to a direction of current running through a conductor. The sensor includes a prism having a high Verdet constant for high sensitivity to magnetic fields, which cause an angle of polarization of the polarized light to be rotated as an indication of the magnitude of current. A polarizing beamsplitter having a low Verdet constant is mounted to the prism so that incoming light that is traveling in a direction orthogonal to the magnetic field being sensed across the airgap is insensitive to unwanted magnetic fields produced by nearby conductors. The distance the light travels in this orthogonal direction is minimized, reducing the overall volume of the sensor, making a compact sensor highly sensitive to magnetic fields of interest, largely insensitive to unwanted magnetic fields, and having a very high dynamic range for sensing current.

A MOCT metering system includes a cutoff module that ensures zero output when values from an optical module fall below a threshold value. The cutoff module includes an RMS to DC converter that drives a comparator. The comparator drives a switch that causes the cutoff module to pass through the measured signal unmodified if above a threshold value and to output a zero voltage signal if below a threshold value.

An optical sensor that senses current by directing polarized light across an airgap that is orthogonal to a direction of current running through a conductor. The sensor includes a prism having a high Verdet constant for high sensitivity to magnetic fields, which cause an angle of polarization of the polarized light to be rotated as an indication of the magnitude of current. A polarizing beamsplitter having a low Verdet constant is mounted to the prism so that incoming light that is traveling in a direction orthogonal to the magnetic field being sensed across the airgap is insensitive to unwanted magnetic fields produced by nearby conductors. The distance the light travels in this orthogonal direction is minimized, reducing the overall volume of the sensor, making a compact sensor highly sensitive to magnetic fields of interest, largely insensitive to unwanted magnetic fields, and having a very high dynamic range for sensing current.