Abb Schweiz Ag

Abb Research Ltd.

Abb Power Grids Switzerland Ag

Hitachi Energy Ltd

Hitachi Energy Switzerland Ag

Xun Gu

Klaus Bohnert

Andreas Frank

Sergio Vincenzo Marchese

Philippe Gabus

Georg Müller

Georg Mueller

Lin Yang

Tobias Erford

Yang Lin

Burak Büyükkavir

Georg Müeller

Sergio Vincenzo Machese

Georg MÜLLER

The invention relates to a spliced optical fiber comprising a first and second polarization-maintaining optical fiber connected at ends by splicing; to fiber optic current sensors; and to a method for protecting the spliced optical fiber against mechanical stress and/or humidity. A protection tube is arranged around the spliced optical fiber in a splice section of the spliced optical fiber. A first and second end of the protection tube is sealed to the spliced optical fiber by first and second sealing arrangement for protecting the splice.

Spliced optical fiber with splice protection, current sensor with such spliced optical fiber and method for protecting a spliced optical fiber

In order to measure a voltage, an electro-optic element is placed in an electrical field generated by the voltage, and light is passed from a light source through a Faraday rotator and the electro-optic element onto a reflector and from there back through the electro-optic element and the Faraday rotator, thereby generating a voltage-dependent phase shift between two polarizations of the light. The interference contrast as well as a principal value of the total phase shift between said polarizations are measured and converted to a complex value having an absolute value equal to the contrast and a phase equal to the principal value. This complex value is offset and scaled using calibration values in order to calculate a compensated complex value. The voltage is derived from the compensated complex value.

Interferometric voltage sensor with error compensation

The optical interferometric sensor device comprises an integrated beam splitter having a first facet and a second facet with optical ports arranged therein. On the beam splitter, the beam splitting junctions as well as the optoelectronics-side ports and the sensing-side port are arranged with a mutual displacement along the direction of the first facet. This displacement reduces undesired interference effects caused by stray light. Also, a quarter-wave retarder is provided in a recess of the beam splitter with layers of soft adhesive adjacent to it in order to reduce stress.

Sensor device having an integrated beam splitter

An interferometric sensor and related methods are provided, with a sensing element whereby a measurand induces a relative phase shift between two waves, at least one detector measuring an interference signal between the two waves, and further including a phase shift detection unit having as input the interference signal and determining a first measure representative of the principal value of the relative phase shift, and a contrast detection unit having as input the interference signal for determining a second measure representative of the cross-correlation between the two waves, and a further a processing unit for converting the first and second measures to a measurand value.

Interferometric sensor

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.

Gas-tight compartment and optical voltage sensor with coated electro-optic crystal

A fiber-optic current sensor uses a highly-birefringent spun fiber as sensing fiber. The light is fed through a retarder, which is a detuned quarter-wave or half-wave retarder. It is shown that such detuning can be used to compensate for temperature dependencies of the sensing head.

Fiber-optic current sensor with spun fiber and temperature compensation

In order to measure the contrast of interference in an interference-based, closed-loop, phase-modulating optical sensor device, the gain of the feedback loop in a feedback controller is evaluated. This gain is found to be a measure for the contrast. The contrast evaluated in this way can e.g. be used for period-disambiguation when determining the measurand of the sensor device. The sensor device can e.g. be a high-voltage sensor or a current sensor.

Closed-loop interferometric sensor using loop gain for determining interference contrast

In a fiber-optic current sensor, a 22.5&#xb0; Faraday rotator, which is part of the sensing fiber coil, determines the working point of the sensor. The coil is operated with substantially linearly polarized light or incoherent substantially left and right circularly polarized light waves. In one arrangement, a polarization beam splitter generates two optical signals that vary in anti-phase with changing current. A signal processor determines the current from the two anti-phase signals. Appropriately detuned and oriented fiber-optic half-wave or quarter-wave retarders before the fiber coil are used to reduce or cancel the adverse effects of temperature and bend-induced birefringence on the measurement signal. Moreover, the temperature may be derived from the difference in the bias of the anti-phase signals and may be used to cancel temperature effects in the signal processor.

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Neuenhof, Switzerland

Xun Gu