Abb Research Ltd.

Abb Technology Ag

Hitachi Energy Ltd

Robert Wueest

Klaus Bohnert

Andreas Frank

Luiz V Cheim

Philippe Gabus

Oleg Kouzmine

Sensor structure () is provided for online monitoring of levels of Furans in oil of a transformer tank. The sensor structure includes a UV light source (), a filter () permitting only UV light of a certain wavelength range to pass, a window () permitting the filtered UV light to passes there-through and a UV light detector () to receive UV light that passes through the window. When the sensor structure is mounted to the transformer tank that is online so that the window is exposed to oil, and Furans in the oil are being monitored, the Furans will absorb UV light, creating a difference in UV light received by the light detector when compared to the UV light received by the light detector when the monitored oil has no Furans therein. The output signal of the light detector is substantially proportional to a total of Furans in the monitored oil.

Sensor structure for online monitoring of furans in power transformers

A fiber optic current or magnetic field sensor uses a sensing fiber in a coil for measuring a current or a magnetic field and has a retarder for converting between linearly polarized light and elliptically polarized light. The retardation of the retarder, its temperature dependence as well as its azimuth angle in respect to the plane of the fiber coil are optimized in dependence of the birefringence in the sensing fiber in order to minimize the influence of temperature variations and manufacturing tolerances on the overall scale factor of the sensor.

Temperature compensated fiber optic current or magnetic field sensor with insensitivity to variations in sensor parameters

A method is provided for tuning the fiber optic retarder of a fiber optic current sensor towards a desired temperature dependence, the sensing fiber is exposed to a magnetic field or corresponding electric current and the sensor signal as well as the signal's dependence on the retarder temperature are measured. From this initial sensor signal and its temperature dependence, a target sensor signal can be determined, at which the dependence on the retarder temperature equals a desired value. Then, the retarder is thermally treated until the sensor signal reaches the target value. The method obviates the need for repetitively measuring the temperature dependence during the tuning process.

Method for manufacturing a fiber optic current sensor with inherent temperature compensation of the faraday effect

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Zurich, Switzerland

Robert Wueest