Abb Research Ltd.

Asea Brown Boveri Inc.

Abb Schweiz Ag

Abb Vetco Gray Incorporated

Hubert Brandle

Klaus Bohnert

Philippe Gabus

Roland Stierlin

Charles Edward Jennings

Norman Brammer

Lutz Niemeyer

Andreas Frank

Thomas Alfred Paul

Axel Kramer

Ken-Yves Haffner

Walter Ruegg

Jiri Talir

Jadran Kostovic

Lothar Schultheis

Tone Schanke

Walter Gribi

A method and device for estimating a density value &#x3c1;indicative of a true density &#x3c1; or for estimating a viscosity value &#x3b7;indicative of a true viscosity &#x3b7; of a fluid is disclosed. For this, a first resonance frequency fof a first mechanical oscillator in a reference volume and a second resonance frequency fof a second mechanical oscillator in contact with the fluid are measured. The estimated value &#x3c1;or &#x3b7;is then derived using these resonance frequencies fand f. During this derivation, at least one fluid-temperature- or fluid-pressure-dependent parameter of the fluid is used. Additionally or alternatively, the first (i.e. reference) mechanical oscillator is arranged in contact with a reference fluid. Thus, fundamental errors in the derivation of the estimated value &#x3c1;or &#x3b7;are reduced and the estimated value becomes more reliable.

Method for measuring a fluid density or a fluid viscosity

The current in a conductor is measured by exploiting the Faraday effect in a sensing fiber. The light returning from the sensing fiber is split into at least two parts, at least one of which is analyzed by a first circular analyzer for generating a first signal. A second part may e.g. be analyzed by a second circular analyzer, and a third part may be analyzed by a linear analyzer. By combining the signals obtained in this way, the current induced phase delay in the returning light can be measured efficiently and accurately.

Fiber-optic current sensor with polarimetric detection scheme

The invention relates to a fiberoptic current or magnetic field sensor having a plurality of sensor heads, and to a corresponding measurement method. The sensor has a light source: N&#x2267;2 sensor heads; at least one phase modulation unit; a detector; a control and evaluation unit. The at least one phase modulation unit is connected to at least one of the sensor heads. Lightwaves can be differentially phase-modulated in a non-reciprocal fashion by means of the at least one phase modulation unit. Modulation amplitudes &#x3c6;and modulation frequencies vare selected as a function of modulation-relevant optical path lengths l.

Fiberoptic current sensor having a plurality of sensor heads

The invention relates to a frequency-coded fiber laser pressure sensor ( ) which is especially suitable for measuring isotropic pressures in oil wells. The sensor principle provided for in the invention is based on the fact that in a fiber laser ( ) doped with Er a monomode or bimodal sensor fiber ( ) is positioned whose pressure-related birefraction results in a frequency shift and beat frequencies between the orthogonal linear polarisation modes x, y or the spatial modes LP and LP line. The beat frequencies are easily measured using a frequency counter ( ). Temperature-related variations in birefraction are compensated in a differential arrangement of two sensor fiber segments ( ). Fiber-integrated Bragg gratings ( ) with low bandwidths (0.2 nm) are especially suitable as laser end reflectors. The pressure sensor ( ) is characterized by a large measurement range (100 Mpa) and a high triggering capacity , (kPa), is readily multiplexed and can be housed in a very compact, light-weight and robust pressure-resistant housing ( ).

Fiber laser pressure sensor

The subject matter of the present invention is a fiber-optic outdoor high-voltage sensor 1. The known sensor principle is based on the fact that a piezoelectric quartz cylinder 3 wound with a glass fiber 4a effects a voltage-proportional fiber strain which is measured interferometrically. According to the invention, a 420 kV outdoor sensor 1 is created by virtue of the fact that several quartz cylinders 3 and electrically conductive spacing elements 5 are arranged in an alternating fashion one behind another and are sealed in a silicone-shielded 17 insulating tube 16 by means of polyurethane 18 or silicone 21. Dividing the high voltage between several spaced, E-field integrating sensor elements 2 permits simple field control and a very high measuring accuracy. In addition, the fiber-optic voltage sensor 1 is distinguished by a low outlay on insulation, compactness and low weight, and can easily be scaled to other voltage levels and be effectively combined with optical current sensors 38.

Fiber-optic voltage sensor for outdoor high-voltage installations

Without special measures, a fiber-optic current sensor coil (11) and fiber-optic .lambda./4 time delay elements (9, 9'), which are connected in series with the current sensor coil (11), are temperature-dependent with respect to a relative phase lag of light passing through. In order to avoid a temperature correction or temperature compensation, the current sensor coils (11) and, if appropriate, also the .lambda./4 time delay elements (9, 9') are annealed, so that virtually no mechanical stresses remain in the optical fibers. The current sensor coil (11) is preferably mounted unrestrained in a capillary (20) filled with a protective gas. The capillary (20) is embedded in a gastight fashion in a potting compound (22) made from polyurethane, and is thus also mechanically protected.

Magneto-optic current sensor having a mechanically stress-free

An inductive pressure transducer senses fluid pressure within a tubular member by passing an alternating current within an inductor coil to generate a magnetic field. The magnetic field passes through a gap between the tubular member and the inductor coil, and into an exterior portion of the tubular member. A detector means senses the net energy transferred from the inductive coil by the magnetic field, which indicates the fluid pressure within the tubular member.

Inductive pressure transducer

The device serves to measure the density of a gas, in particular of the insulating gas of a gas-insulated electrical installation. It contains two resonators (11, 12) each comprising a piezoelectric crystal (14, 15) and each comprising two electrodes applied to the crystal. A first (11) of the two resonators (11, 12) is mounted in a first chamber (5) containing the gas to be measured, whereas a second (12) is mounted in a second chamber (6) sealed with respect to the gas. Despite small dimensions and despite simple and robust construction, this device is intended to have a high measurement precision over a long period of time. This is achieved by drawing the two resonators (11, 12) from a multiplicity of similar resonators manufactured by mass production and not subjected to a frequency alignment. The first resonator (11) is unaltered with respect to the manufacture in mass production. The second resonator (12) is likewise unaltered with respect to the manufacture in mass production and, under vacuum and with equality of temperature, it has the same resonance frequency as the first resonator (11) within a specified frequency tolerance. The second resonator (12) may, however, also be modified, by altering its electrodes (18, 19), in such a way that, under vacuum and with equality of temperature, it has the same resonance frequency as the first resonator (11) within the specified frequency tolerance.

Device for measuring gas density

In a gas-insulated switchgear having an isolated-phase bus, a current-carrying bus (2) with a given external radius R.sub.1 is arranged coaxially in a cylindrical enclosure with a given external radius R.sub.2, the voltage of the current carrying bus is measured using optical fiber voltage transducers. For this purpose, at least three identical piezoelectric sensor elements are provided. They are arranged essentially at a distance corresponding to the internal radius R.sub.2 from an axis of the current carrying bus in the enclosure at identical angular distances. The sensor elements are preferably accommodated together with an optical fiber curent transducer in a metal ring that can be inserted into the enclosure.

Arrangement for voltage measurement in a GIS installation

A fiber-optical current transformer including a sensor coil, operated in reflection mode, with a sensor fiber (5) for detecting a current utilizing of the Faraday effect. A light source (1) couples light into an incoming first HB fiber (2a). At the end of the first HB fiber (2a), a fiber-optical polarizer (4) is preferably located which ensures a direction of polarization in parallel with a given birefringence axis of the first HB fiber (2a). A Y splitter (3) couples, on the one hand, the supplied light of the first HB fiber (2a) into the sensor fiber (5) and, on the other hand, the light coming from the sensor fiber (5) into an outgoing second HB fiber (2b). The second HB fiber (2b) is rotated with its birefringence axes by 45.degree. with respect to the birefringence axes of the first HB fiber (2a).

Rugged fiber-optical current sensor based on the Faraday effect

A connector (2) for an optical cable (1) having at least one glass fiber (4.1, 4.2) is characterized in that the plug contact is electrical and the signal transmission is optical. For this purpose, an electrical plug contact (5.1, 5.2) is provided for the at least one glass fiber (4.1, 4.2), as well as a first converter for converting an electrical signal into an optical signal and/or a second converter for converting an optical signal into an electrical signal. The at least one glass fiber (4.1, 4.2) of the optical cable (1) is connected directly to the the first and second converters, respectively. The first and second converters, respectively, are e.g. embodied by light-emitting diodes and photodiodes, respectively.

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Oberengstringen, Switzerland

Hubert Brandle