An optical voltage sensor for measuring voltage on an underground power line or for use in other scenarios in which access to a conductor is available through a blind hole. The optical voltage sensor includes a light modulating member, such as a Pockel's crystal. A reflective, conductive member is positioned at one end of the light modulating member and another conductive member is positioned at an opposed end. A voltage capacitively coupled to the reflective conductive member induces a voltage across the light modulating member, thereby impacting the amount of modulation. A beam of light is directed through the crystal and reflected back out of the crystal, where the amount of modulating can be measured. The amount of modulation indicates a measured voltage, and can be transmitted to a monitoring station where processing can determine the status of the power grid or generate other results based on the measured voltage.

A voltage sensor includes a vibrator configured to be supported by a mechanical supporting portion and to be given a floating potential, a drive electrode configured to be disposed adjacent to the vibrator and to resonate the vibrator with applied AC voltage, a driver configured to apply an AC voltage that crosses 0 V to the drive electrode, a fixed electrode configured to be disposed adjacent to the vibrator with a gap formed between the fixed electrode and the vibrator, and a calculator configured to detect a magnitude of a measurement target voltage based on a change of a resonant frequency of the vibrator when the measurement target voltage is applied to the fixed electrode.

A voltage sensor includes a vibrator configured to be supported by a mechanical supporting portion and to be given a floating potential, a drive electrode configured to be disposed adjacent to the vibrator and to resonate the vibrator with applied AC voltage, a driver configured to apply an AC voltage that crosses 0 V to the drive electrode, a fixed electrode configured to be disposed adjacent to the vibrator with a gap formed between the fixed electrode and the vibrator, and a calculator configured to detect a magnitude of a measurement target voltage based on a change of a resonant frequency of the vibrator when the measurement target voltage is applied to the fixed electrode.

An optical fiber loop current sensing controller module, which integrates with the electrical power, and data processing and transmission, back-plane of a digital micro-processor relay for modular integration with the protection, metering, and communication functions of an electrical SCADA system. An optical transmitter is energized from a DC source on the digital relay, and emits unpolarized light of known intensity and wavelength to a linear polarizer, and the Stokes vector polarization parameters are calculated from the Mueller Matrix of the linear polarizer and the known intensity of the unpolarized optical input from the transmitter, which is then launched in alignment with the transmission axes of a polarization maintaining optical fiber link to a remote and passive fiber loop current sensor, where the linearly polarized optical pulse traverses a complete circular path around an energized conductor and experiences polarization state rotation in relation to the magnetic flux density which is proportional to current flow based on Ampere's law. The rotated polarized optical pulse is transmitted back to the optical fiber loop current sensing controller module via a return fiber optic cable, where the Stokes vector polarization parameters for the returned optical pulse having experienced Faraday rotation are calculated by splitting the pulse into four components, passing these components through a linear horizontal polarizer, a linear vertical polarizer, a linear polarizer with transmission axis set at 45 degrees, and a right circular polarizer comprised of a quarter wave plate connected to a linear polarizer with transmission axis set at 45 degrees, respectively, and where the four separate output channels of the four polarizing elements are then connected to be orthogonally incident a quadrature array of four separate photodetectors which transduce the optical intensity to electrical quantities, and the four optical receiver outputs connect to a digital data processing bus, where the Stokes vector parameters for the polarized optical pulse are calculated directly from the array of optical intensity values transduced by the photodetectors, and the change in polarization state is calculated by comparing the initial linear polarization Stokes vector parameters reference state transmitted to the remote fiber loop current sensor with the measured Stokes parameters of the rotated polarized optical pulse received back. This data is then converted to a calibrated current measurement, which is transmitted to a signal and data processing back plane of the digital micro processor relay via digital output ports on the optical current sensing controlle

An optical fiber loop current sensing controller module, which integrates with the electrical power, and data processing and transmission, back-plane of a digital micro-processor relay for modular integration with the protection, metering, and communication functions of an electrical SCADA system. An optical transmitter is energized from a DC source on the digital relay, and emits unpolarized light of known intensity and wavelength to a linear polarizer, and the Stokes vector polarization parameters are calculated from the Mueller Matrix of the linear polarizer and the known intensity of the unpolarized optical input from the transmitter, which is then launched in alignment with the transmission axes of a polarization maintaining optical fiber link to a remote and passive fiber loop current sensor, where the linearly polarized optical pulse traverses a complete circular path around an energized conductor and experiences polarization state rotation in relation to the magnetic flux density which is proportional to current flow based on Ampere's law. The rotated polarized optical pulse is transmitted back to the optical fiber loop current sensing controller module via a return fiber optic cable, where the Stokes vector polarization parameters for the returned optical pulse having experienced Faraday rotation are calculated by splitting the pulse into four components, passing these components through a linear horizontal polarizer, a linear vertical polarizer, a linear polarizer with transmission axis set at 45 degrees, and a right circular polarizer comprised of a quarter wave plate connected to a linear polarizer with transmission axis set at 45 degrees, respectively, and where the four separate output channels of the four polarizing elements are then connected to be orthogonally incident a quadrature array of four separate photodetectors which transduce the optical intensity to electrical quantities, and the four optical receiver outputs connect to a digital data processing bus, where the Stokes vector parameters for the polarized optical pulse are calculated directly from the array of optical intensity values transduced by the photodetectors, and the change in polarization state is calculated by comparing the initial linear polarization Stokes vector parameters reference state transmitted to the remote fiber loop current sensor with the measured Stokes parameters of the rotated polarized optical pulse received back. This data is then converted to a calibrated current measurement, which is transmitted to a signal and data processing back plane of the digital micro processor relay via digital output ports on the optical current sensing controlle

This patent application discloses techniques and devices for sensing or measuring electric currents and/or temperature based on photonic sensing techniques. An optical current sensor head is located near or at a current-carrying conductor so that a magnetic field associated with the current is present at a Faraday material and the optical detection unit detects the light from the Faraday material to determine a magnitude of the current. An optical temperature sensor head is located near or at a location so that the temperature at a temperature-sensing Faraday material is reflected by the optical polarization rotation which is detected to determine the temperature.

Optical fiber based current measuring equipment for measuring the current circulating through a conductor. The equipment includes an interrogator having a light emitter and a light receiver, and a sensing portion close to the conductor, the interrogator and the sensing portion being connected through at least one standard single-mode intermediate fiber. The light emitter of the interrogator is configured to emit sets of at least two polarized light pulses to the sensing portion, the pulses being polarized with a specific degree difference, and the light receiver (4) is configured to determine the current circulating through the conductor depending on the pulses it receives in return from the sensing portion. A method for measuring the current circulating through a conductor with the use of an optical fiber based current measuring equipment is also provided.

The invention relates to an assembly of a gas-tight compartment and an optical voltage sensor that further comprises a module. The module comprises an electro-optic crystal and electrodes, wherein the electro-optic crystal is the only element of the module to mechanically connect the two electrodes and to bridge the potentials of the two electrodes. The assembly is particuarly suited to measure direct current voltages.

A method of measuring fluctuations in electric fields is disclosed, the method comprising the step of: placing a Liquid Crystal Device in communication with the electric field, the device having disparate orthogonal polarization sensitivity to an external electric field; utilizing an optical probe beam having a known polarization state to interrogate the liquid crystal of the liquid crystal device to produce a response beam; and analyzing the polarization state of the response beam to provide an indicator of the corresponding fluctuations in the electric field.

A method of measuring fluctuations in electric fields is disclosed, the method comprising the step of: placing a Liquid Crystal Device in communication with the electric field, the device having disparate orthogonal polarization sensitivity to an external electric field; utilizing an optical probe beam having a known polarization state to interrogate the liquid crystal of the liquid crystal device to produce a response beam; and analyzing the polarization state of the response beam to provide an indicator of the corresponding fluctuations in the electric field.