Optical Fiber Current Sensor with Opposite Windings
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Solution Overview
Problem
Existing optical fiber-based current measuring equipment faces challenges in accurately measuring low current values and direct current with high signal/noise ratios, often requiring filters for noise elimination, which can be impractical.
Innovation Solution
The equipment employs a configuration with two optical fiber windings of equal length but opposite directions, coupled through a splitter, and a Faraday mirror setup, allowing for precise current measurement without filters by using the phase opposition of polarization deviations to enhance noise cancellation and dynamic range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If filters are used to eliminate noise in optical fiber-based current measuring equipment, then measurement precision for low current values improves, but device complexity increases
Solution Approach 1:
The patent converts the harmful noise signal into a beneficial measurement signal by using two optical fiber windings wound in opposite directions. The noise affecting both windings equally becomes a common-mode signal that can be eliminated through differential measurement, while the current-induced polarization rotation becomes the useful measurement signal. This approach eliminates noise without requiring additional filters, resolving the contradiction between measurement precision and device complexity.
Solution Approach 2:
The patent changes the configuration parameter of the optical fiber windings by winding them in opposite directions while maintaining equal length. This parameter change creates phase opposition in the polarization deviation responses, enabling noise cancellation through differential measurement. The solution achieves improved measurement precision for low current values without adding complex filtering components.
2Measurement precision
If filters are used for noise elimination in direct current measurement, then measurement precision improves, but ease of operation deteriorates due to impractical filter requirements
Solution Approach 1:
The patent transforms the noise problem into a solution by using opposite-direction windings to create phase opposition. This converts the harmful noise into a cancelable common-mode signal, achieving high measurement precision for direct current without requiring impractical filters. The system becomes easier to operate as no complex filtering is needed.
3Measurement precision
If two optical fiber windings with opposite directions are used, then noise elimination improves and measurement precision increases, but device complexity increases due to additional components
Solution Approach 1:
The patent segments the measurement function into two separate optical fiber windings with opposite directions. Each winding independently responds to the current, and their differential combination provides noise cancellation. This segmentation achieves high measurement precision while keeping each individual component simple and standard.
Solution Approach 2:
The patent merges the output signals from the two opposite-direction windings through a differential measurement approach. By combining the signals in opposition, the common-mode noise cancels out while the current signal is doubled, achieving enhanced measurement precision without requiring complex additional components beyond standard optical elements.
4Measurement precision
If filters are used to eliminate noise, then signal/noise ratio improves, but productivity decreases due to additional processing requirements
Solution Approach 1:
The patent converts noise elimination from a post-processing filtering operation into an inherent property of the measurement configuration. By using opposite-direction windings, noise is canceled at the source through phase opposition, achieving high signal-to-noise ratio without additional processing steps. This maintains productivity while improving measurement precision.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration enables precise measurement of currents across a wide range, including low values and direct current, with improved noise elimination and dynamic range, allowing for accurate determination of conductor currents without the need for filters.
Implementation Method 1
Said sensors work according to the Faraday effect, i.e., the magnetic field generated by the current circulating through the conductor causes a rotation in the polarization of light circulating through the optical fiber arranged around the conductor.
Implementation Method 2
a first sensing branch comprising a first optical fiber winding arranged in the proximity of the conductor and a first Faraday mirror
Data Source
AI summary
Optical fiber-based measuring equipment for measuring the current circulating through at least one conductor. The measuring equipment includes an interrogator and a sensing portion connected to the interrogator and configured for being arranged in the proximity of the conductor. The sensing portion includes a first input branch and a second input branch coupled by means of a splitter to a first sensing branch and to a second sensing branch. The first sensing branch includes a first optical fiber winding arranged in the proximity of the conductor, and the second sensing branch includes a second optical fiber winding arranged in the proximity of the conductor, the first optical fiber winding and the second optical fiber winding having the same number of turns that are, however, wound in opposite directions.