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:
Oct. 22, 1991
Filed:
May. 16, 1990
Robert C Miller, New Alexandria, PA (US);
ABB Power T&D Company, Inc., Blue Bell, PA (US);
Abstract
A voltage measuring system utilizes an electro-optic voltage transducer (EOVT) in which two beams of polarized light injected into one end of an electro-optic crystal parallel to its fourfold axis of rotary inversion are reflected back through the crystal by a prism so that the optical inputs and outputs, including polarizers, collimators, optic fibers, and fractional wave plates where required, are all located at one end of the crystal, which is preferably connected to the low side of the voltage to be measured. The EOVT is supported substantially only at the end with the optical inputs and outputs, with the free end on which the prism is mounted being substantially unsupported. In one embodiment of the invention, a triangular prism is used to reflect the polarized light back through the prism, in another a pyramid prism is utilized. In the latter case, the material of the prism and, if desired, a metal coating applied to the reflecting faces of the prism, can be selected so as to produce a 1/4 wave phase shift between components of the two polarized light beams parallel to the fast and slow axes, which is needed in addition to the phase shift resulting from the measured voltage for generating an unambiguous representation of voltages exceeding the halfway voltage of the electro-optic crystal, thereby eliminating the need for fractional wave plates. A partial or full metal coating on the prism can be used to electrically connect a transparent electrode located between the prism and the crystal to a conducting spring bearing against the prism for applying the voltage to be measured to the free end of the electro-optic crystal.