Single-Phase Optical Current Transformer Using Segmented Fiber Paths
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional single-phase optical current transformers face challenges in accurately measuring large currents due to saturation of the Faraday rotation angle and poor workability when installed in high-voltage gas insulated switchgear, particularly with temperature differences affecting measurement accuracy and ease of installation.
Innovation Solution
A single-phase optical current transformer design using two short optical paths formed by optical fibers and mirrors, intersecting with the axial direction of the electric conductor, allowing for reliable measurement of large currents without saturation and facilitating easier installation on the outer peripheral surface of a cylindrical container.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a closed loop optical path using optical fiber is used to measure current, then the device size can be reduced and manufacturing is simplified, but the Faraday rotation angle saturates when large currents flow, making accurate measurement impossible
Solution Approach 1:
The closed loop optical path is segmented into four separate optical paths (first, second, third, and fourth optical paths) arranged at different spatial locations around the electric conductor. This segmentation distributes the magnetic field exposure across multiple paths, preventing saturation in any single path while maintaining a compact device structure.
Solution Approach 2:
The measurement signals from the four segmented optical paths are combined through optical coupling to produce a composite measurement signal. This merging of multiple non-saturated signals enables accurate current measurement that overcomes the saturation limitation of individual paths while maintaining compact device size.
2Adaptability or versatility
If the optical path encircles the electric conductor in a closed loop configuration, then the device can be installed on large diameter cylindrical containers, but the installation workability is poor and temperature differences cause measurement errors
Solution Approach 1:
The continuous closed loop optical path is divided into four discrete optical paths positioned at different locations. This segmentation allows each path to be independently installed and adjusted, significantly improving installation workability while maintaining adaptability to large diameter cylindrical containers through strategic positioning.
Solution Approach 2:
Each optical path is positioned at a specific location around the electric conductor, allowing local adaptation to temperature distribution patterns. The spatial distribution of the four paths ensures that temperature differences in any single location do not dominate the measurement, improving measurement accuracy while facilitating easier installation.
3Device complexity
If a single optical path is used, then the device structure is simple, but temperature differences between different parts of the optical path cause measurement errors
Solution Approach 1:
The single optical path is divided into four separate optical paths positioned at different locations. This segmentation distributes the temperature exposure across multiple paths, allowing temperature differences to affect each path differently. The combined measurement signal from all four paths compensates for local temperature effects, improving accuracy while maintaining relatively simple device structure.
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 design prevents saturation of the Faraday rotation angle and reduces temperature-related measurement errors, enabling accurate measurement of large currents while allowing for compact, economical manufacturing and simplified installation and replacement operations.
Implementation Method 1
uses the Faraday effect, which is a rotation phenomenon of polarization plane of a light due to an effection of magnetic field
Implementation Method 2
each of the mirror reflecting the linearly polarized light
Data Source
AI summary
An installation base is secured to part of outer peripheral surface of cylindrical container 1 which has electric conductor 2 arranged thereinside, and a case which stores a Faraday-effect element is detachably secured to the installation base. Faraday-effect element 10 having two optical fibers 24A, 24B of prescribed dimensions, to provide first and second optical paths 11A, 11B maintained in parallel with a predetermined interval therebetween and placed so as to intersect axial direction of electric conductor 2, and having mirror 12 which reflects linearly polarized light at one end surface of each optical fiber. Linearly polarized light from the same light source injected into each of the optical paths 11A, 11B, and current flowing in electric conductor 2 is measured base on the Faraday rotation angle of the linearly polarized light reflected and returned from mirror 12.