Split-Core Current Sensor Assembly for Live Line Installation
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Solution Overview
Problem
Current instrument transformers for high voltage transmission lines are large, expensive, and costly to replace, with no simple or cost-effective way to verify the accuracy of the entire system once installed, especially since they require power-down for replacement.
Innovation Solution
A sensor apparatus with a corona frame and conductor mountable device, featuring a split-core current sensor assembly and GPS/time-syncing capabilities, allowing for accurate, self-contained, and easy installation on live power lines without interrupting the power supply, and enabling compensation for inaccuracies in instrument transformers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional current transformers are used for high voltage transmission lines, then measurement capability is provided, but device size and cost increase significantly
Solution Approach 1:
The current transformer is divided into two separate half-housings (first housing assembly and second housing assembly) that can be installed independently on opposite sides of the conductor. Each housing contains a portion of the magnetic core and winding assembly, allowing the device to function as a complete CT without requiring a single large enclosure, thus reducing overall device volume while maintaining measurement capability.
2Measurement precision
If traditional current transformers are replaced, then system accuracy can be improved, but power down is required causing loss of time and productivity
Solution Approach 1:
The split-core design allows each half-housing to be installed separately on de-energized or live conductors without requiring complete removal of the existing transformer. The two half-housings are then joined together to form the complete assembly, enabling rapid replacement or addition of CTs without prolonged power outages and maintaining productivity.
Solution Approach 2:
The housing assemblies incorporate movable components including the carrier that can slide within the housing to adjust the position of the magnetic core and winding assembly. This dynamic adjustment capability allows for easy installation and alignment during replacement operations, reducing the time required for installation while ensuring proper measurement accuracy.
3Measurement precision
If meters and instrument transformers are calibrated independently in lab, then calibration is performed, but end-to-end system accuracy cannot be verified after field installation
Solution Approach 1:
The current transformer design integrates the magnetic core, winding assembly, and electronic compensation circuitry into a single unified housing assembly. This merging of components allows for end-to-end calibration and verification of the complete measurement system in the field, ensuring that the combined operation of all components achieves the desired measurement accuracy rather than just individual component calibration.
Solution Approach 2:
The CT assembly includes built-in compensation circuitry and electronics that can perform self-diagnosis and calibration verification functions. The device is capable of monitoring its own operation and providing feedback on measurement accuracy, enabling field verification of system performance without requiring external laboratory equipment or complete system disassembly.
4Ease of operation
If split core design is used for easy installation, then installation simplicity improves, but manufacturing complexity increases
Solution Approach 1:
The device is segmented into two identical or mirror-image half-housings, each containing a complete set of mounting features, sealing elements, and connection points. This segmentation simplifies installation as each half can be independently positioned and attached to the conductor, then joined together. The modular nature also simplifies manufacturing by allowing each half-housing to be produced separately using standardized processes, reducing overall manufacturing complexity despite the split design.
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
Enables accurate measurement of power parameters on high voltage lines, facilitates easy installation and verification of system accuracy, and reduces replacement costs by allowing live line installation and auto-positioning, while minimizing corona discharge and environmental impact.
Implementation Method 1
The carrier, current transformer cores and corresponding current transformer windings may form a winding assembly
Implementation Method 2
The corona frame may be an open structure that provides an outer envelope and an inner volume in which corona discharge may be minimized
Data Source
AI summary
A sensor apparatus for measuring power parameters on a power conductor, such as a high voltage transmission line may include a corona structure, an electronics assembly and a conductor mountable device. The corona structure may define an outer boundary surrounding the electronics assembly and the conductor mountable device. The corona structure may shield the electronic assembly and conductor mountable device from a corona produceable with the power conductor. The conductor mountable device may be a power parameter measurement device, such as a current sensor assembly. The current sensor assembly may be a split-core design that includes multiple transformer cores. The electronics assembly and the conductor mountable device may powered from a line voltage suppliable on the power conductor. Data may be wirelessly transmitted and received with the sensor apparatus.