Abstract: 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.

Abstract: A device for measuring an electric field comprises three optical fiber sensors, which each have a piezoelectric sensor element, as well as an interferometer for generating a sensor signal. The optical fiber sensors have piezoelectric sensor elements that exclusively detect with the aid of the inverse piezoelectric effect a predetermined directional component, assigned in each case, of the electric field. The directional components of the different sensor elements are each aligned perpendicular to one another. An evaluation circuit determines the absolute value and direction of the electric field from the sensor signals generated.The sensor elements are preferably formed by a single piezoelectric body, on whose faces the sensor fibers are fixed.

Abstract: In an interferometric fiberoptic sensor with homodyne detection for measuring electrical fields or voltages, the measurement signal is compensated separately from operating point control. The measurement signal originating from the electrical field is compensated in a piezoelectric modulator (5) which consists of modulator elements which are identical with the at least one sensor element (3) with respect to material, geometric shape and crystal orientation. Additional separate apparatus (4) with a sufficiently large phase swing are provided for operating point control. Modulator element and sensor element (3) are essentially at the same temperature so that the temperature-dependence of the matter constants of the sensor element and the temperature-dependence of the fiber interferometer are eliminated. The sensor preferably operates in accordance with the principle of a fiberoptic two-mode interferometer.

Abstract: A fiber-optic voltage sensor comprises at least one fiber-optic, piezoelectric sensor element (2a, 2b, 2c, 2d), which measures a predeterminable directional component of a local electric field. One or more than one piezoelectric sensor elements (2a, 2b, 2c, 2d) are arranged serially between two ends of the fiber-optic voltage sensor, each piezoelectric sensor element (2a, 2b, 2c, 2d) respectively measuring a directional component of a local electric field, which component lies parallel to a path element assigned to it, the path elements as a whole forming an open polygon connecting the two ends of the fiber-optic voltage sensor. Each sensor element (2a, 2b, 2c, 2d) has a gain which is proportional to a length of the path element assigned to it. In a preferred embodiment, the piezoelectric sensor elements (2a, 2b, 2c, 2d) are connected by spacers (3a, 3b, 3c).

Abstract: A fibre-optic sensor for measuring a particular directional component of an electric field comprises a piezoelectric body (4) and a glass fiber (5a) which is rigidly connected to the piezoelectric body (4) in a given length section. A crystal class and a crystallographic orientation of the piezoelectric body (4) is selected in such a manner that only the directional component which is parallel to a given body axis (h) of the piezoelectric body (4) causes a change in a length of the glass fiber (a) by means of an inverse piezoelectric effect. The change in length is measured interferometrically. In a preferred embodiment, the piezoelectric body has the shape of a disk, of a plate or of a hollow cylinder.