Insulated Conductor Splice Fitting for High Voltage Subsurface Heaters
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Solution Overview
Problem
Conventional mineral insulated (MI) cable splice designs are not suitable for high voltage applications above 1000 volts, 1500 volts, or 2000 volts and fail at elevated temperatures, requiring improved compaction of mineral insulation to match the level in the insulated conductor, while also needing higher bending and tensile strengths to withstand subsurface conditions.
Innovation Solution
A fitting system that couples insulated conductors using a sleeve and core coupling with electrically insulating material compression, providing enhanced mechanical and electrical integrity, and featuring tapered interior volumes to reduce electric field intensities and increase the operating voltage and temperature range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional MI cable splice designs are used, then the splice can be manufactured with simple structures, but the splice fails at high voltages above 1000 volts and elevated temperatures
Solution Approach 1:
The splice is divided into multiple functional components including a body portion, end portions with tapered interior volumes, and separate insulator insertion paths. This segmentation allows each component to be optimized for specific functions (compaction, insulation, electrical connection) while maintaining overall reliability at high voltages and temperatures
Solution Approach 2:
The splice design incorporates three-dimensional tapered interior volumes at the end portions that converge toward the center. This dimensional feature creates progressive compaction zones that enhance mineral insulator density without requiring complex external compaction equipment, resolving the contradiction between simplicity and high-voltage reliability
2Reliability
If mineral insulation compaction is increased to match the level in the insulated conductor, then the splice can operate at high voltages, but the manufacturing process becomes more complex and difficult
Solution Approach 1:
The tapered interior volumes are pre-formed during splice manufacturing before mineral insulation installation. This preliminary action creates built-in compaction zones that automatically densify the mineral insulation as it is inserted and compressed along the tapered paths, eliminating the need for complex post-installation compaction equipment while achieving high-voltage operational reliability
Solution Approach 2:
The interior volume geometry is changed from cylindrical to tapered, with the cross-sectional area progressively decreasing toward the center. This parameter change in the splice structure creates mechanical compaction forces that increase mineral insulation density without requiring excessive external compression forces, simplifying the manufacturing process while ensuring high-voltage performance
3Reliability
If the splice is designed for high voltage operation, then leakage currents are reduced, but the electric field intensities increase requiring tapered interior volumes to reduce breakdown risk
Solution Approach 1:
The tapered interior volumes create localized regions of gradually changing electrical field distribution. By concentrating the field reduction function in specific geometric zones rather than uniformly throughout the splice, the design achieves lower peak electric field intensities and reduced breakdown risk while maintaining overall high-voltage reliability and minimal leakage currents
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
The solution enables reliable operation at high voltages and temperatures, reducing leakage currents and enhancing the margin between operating voltage and electrical breakdown, thus ensuring long-duration performance in subsurface environments.
Implementation Method 1
an interior volume of the sleeve is configured to be at least partially filled with electrically insulating material
Implementation Method 2
featuring tapered interior volumes to reduce electric field intensities and increase the operating voltage and temperature range
Data Source
AI summary
Systems and methods for heaters used in treating a subsurface formation are described herein. Certain embodiments relate to systems for insulated conductors used in heater elements. More particularly, fittings for splicing together insulated conductors and/or insulated conductors to other conductors are described.