Method of updating the scale factor of apparatus for measuring an alternating electric current by means of the faraday effect
US4797607A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Apr 11, 1988 |
| Grant date | Jan 10, 1989 |
| Priority date | — |
| Expiry date | Apr 11, 2008 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01R35/005
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
The method is intended for use in a step-down high tension current measuring apparatus using the Faraday effect and including a Sagnac interferometer having an optical loop constituted by a fiber (47) surrounding the high tension conductor (11) conveying the alternating current to be measured and terminating at an integrated optical circuit (43) which delivers an output light beam to an electronic circuit with the optical power of the light beam having a component in its spectrum at a frequency which is a sinusoidal function of the phase difference generated by the Faraday effect, with the coefficient of proportionality being referred to as a scale factor. The method consists in periodically updating the scale factor used for interpreting measurements on the basis of D.C. components in the output signal from the interferometer which appear in response to two successive disturbances which modify the Faraday effect and which are caused by means of a test direct current taking two different successive values and applied to auxiliary coils (44, 45).
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.