Edward A. Ulmer - Clearwater FL Thomas J. Meyer - Pinellas Park FL
Assignee:
Square D Company - Palatine IL
International Classification:
G01R 1900
US Classification:
324 96
Abstract:
An optical current transducer for measuring current in a high voltage transmission line includes a temperature compensated light source of nominal predetermined intensity and wavelength, a Faraday rotation device where Faraday rotation impressed on the light exiting the light source is proportional to the intensity of the electrical current to be measured. A hermetic tank encloses the Faraday rotation device to provide protection from the environment. An electronic circuit converts the optical output of the Faraday rotation device to an electrical signal in direct proportion to and in phase with the current to be measured.
Method Of Eliminating The Effects Of Birefringence From The Detection Of Electric Current Using Faraday Rotation
An improved method and apparatus for measuring a target electric current utilizing a Faraday effect in which an optical medium is magnetically coupled with the target electric current and light is passed through the optical medium at an orientation for which the effects of birefringence on the optical medium can be disregarded in comparison with the Faraday effect, and the light departing from the optical medium is measured and analyzed in a manner permitting the target current to be accurately determined.
Edward A. Ulmer - Clearwater FL William P. Hooper - Largo FL
Assignee:
Square D Company - Palatine IL
International Classification:
G01R 3100 G01J 400
US Classification:
250214R
Abstract:
A light detector measures the intensity of two different light beams, computes a ratio of an AC to a DC component for each light beam, and computes a quotient by dividing a first of the above ratios by a second of the above ratios. A light detector has a first photodetector, means, responsive to the first photodetector, for computing a first ratio of an AC component to a DC component of the intensity of a first light detected by the first photodetector, means for producing a first average value of the first ratio, a second photodetector, means, responsive to the second photodetector, for computing a second ratio of an AC component to a DC component of the intensity of the second light detected by the second photodetector, means for producing a second average value of the second ratio, and means for computing a quotient by dividing the first average value of the first ratio by the second average value of the second ratio.