Electricity: measuring and testing – Measuring – testing – or sensing electricity – per se – Using radiant energy
Patent
1995-09-29
1998-06-09
Nguyen, Vinh P.
Electricity: measuring and testing
Measuring, testing, or sensing electricity, per se
Using radiant energy
G01R 3100
Patent
active
057640467
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to a method and device for measuring an alternating electrical current in a current conductor in general, and more particularly to such a measurement method and device in which temperature compensation is provided in a simple manner.
A method for measuring an alternating electrical current in a current conductor using a Faraday element associated with the current conductor into which linearly polarized light is coupled, the plane of polarization of this linearly polarized light then being rotated through a measuring angle on the basis of the Faraday effect, the measuring angle being a measure of the alternating electrical current in the current conductor; the light with the polarization plane rotated through the measuring angle coupled out of the Faraday element and divided into two light signals having different planes of polarization; and each of the two light signals converted into an electrical signal which is a measure of the intensity of the corresponding light signal, and a device for carrying out this method is described, for example, in U.S. Pat. No. 4,755,665.
Thus, optical measuring devices for measuring an electrical current in a current conductor using the Faraday effect, which are also referred to as magneto-optic current transducers are known. The Faraday effect is understood to be the rotation of the plane of polarization of linearly polarized light in dependence upon a magnetic field. The angle of rotation is proportional to the path integral over the magnetic field along the path covered by the light, using the Verdet constant as a proportionality constant. The Verdet constant is dependent upon the material through which the light is passing, on its temperature, and on the wavelength of the light. To measure the current, a Faraday element, which is made of an optically transparent material that demonstrates the Faraday effect, generally glass, is arranged in the proximity of the current conductor.
Linearly polarized light is sent by a transmitter unit through the Faraday element. The magnetic field produced by the electrical current effects a rotation of the plane of polarization of the light in the Faraday element through a polarization angle of rotation, which can be evaluated by an evaluator unit as a measure of the strength of the magnetic field and, thus, of the intensity of the electric current. The Faraday element generally surrounds the current conductor, so that the polarized light circulates around the current conductor in a quasi closed path. As a result, the size of the polarization angle of rotation is roughly directly proportional to the amplitude of the measuring current.
In one prior device, the Faraday element is designed as a solid glass ring around the current conductor. In this specific embodiment (EP-B1-0 088 419), the light circulates around the current conductor once.
In another known device, the Faraday element is designed as part of an optical monomode fiber, which surrounds the current conductor in the form of a measuring winding. Thus, for one pass-through, the light circulates around the current conductor N times, where N.gtoreq.1 is the number of turns of the measuring winding. Two types of such magneto-optic current transducers having an optical-fiber measuring winding are known, namely the transmission type and the reflection type. In the case of the transmission type, the light is coupled into one end of the fiber and coupled out again at the other end, so that the light only passes through the measuring winding once. On the other hand, in the case of the reflection type, the other end of the fiber has a reflecting surface, so that the light coupled into the first end is reflected at this other reflecting end; it passes through the measuring winding a second time in the reverse direction, and is emitted at the first end again. Due to the non-reciprocity of the Faraday effect, given a reverse pass-through, the plane of polarization of the light is rotated again by the same amount in the same directio
REFERENCES:
patent: 4563639 (1986-01-01), Langeac
patent: 4755665 (1988-07-01), Ulmer, Jr. et al.
patent: 4973899 (1990-11-01), Jones et al.
patent: 5053617 (1991-10-01), Kakizaki et al.
patent: 5382901 (1995-01-01), Okajima et al.
patent: 5416860 (1995-05-01), Lee et al.
patent: 5486754 (1996-01-01), Cruden et al.
patent: 5500909 (1996-03-01), Meier
Proceedings of the Conference on Optical Fiber Sensors OFS/1988, New Orleans (US), pp. 288-291 (Month Unavailable).
Kobert Russell M.
Nguyen Vinh P.
Siemens Atkiengesellschaft
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