The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Apr. 16, 1991
Filed:
Aug. 03, 1989
Carlo F Petronio, Ross Township, Allegheny County, PA (US);
ABB Power T & D Company, Inc., Blue Bell, PA (US);
Abstract
In a measuring device including a magnetic-optic current transformer (2) defining an optical path having an input (4) and an output (6) and having an optical transmission characteristics such that the relation between optical energy supplied to the input (4) and optical energy arriving at the output (6) is a function of an electrical parameter being monitored, an electrically driven photoemitter (8) disposed for supplying optical energy to the optical path input (4), a photodetector circuit (10, 12) optically coupled to the optical path output (6) for producing an electrical signal representative of the optical power arriving at the output (6), and a control circuit (14,16) connected between the photodetector circuit (10,12) and the photoemitter (8) for controlling the light energy supplied by the photoemitter (8) and forming with the transformer (2) a high pass filter having a corner frequency, the control circuit (14,16) is composed of an amplifier (20) and a first compensation unit (24,26) connected to form a negative feedback path of the amplifier (20) for supplying a negative feedback signal which is linearly proportional to the optical power emitted by the photoemitter (8) for causing the corner frequency value to be independent of the relative between the optical power at the input (4) to the path and the optical power at the output (6) of the path; and a second compensation unit (R.sub.3,R.sub.4) is operatively connected for causing the corner frequency value to be independent of the temperature of the control circuit (2).