Segmented Fuse Wire for High-Pressure Capacitor Arc Quenching
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In high-pressure subsea applications, the arc behavior in power capacitors differs from atmospheric conditions, leading to a risk of closed circuit formation after current limiting operations, which compromises the reliability of capacitor elements.
Innovation Solution
The power capacitor design features fuse wires with alternating sections in physical contact and without physical contact with a solid electrical insulation system, immersed in a dielectric liquid, to prevent the formation of continuous soot tracks that could cause a closed circuit, utilizing a housing with a passive pressure compensator to manage subsea pressures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fuse wires are operated in high-pressure subsea applications to limit current during capacitor element failures, then current limiting behavior is achieved, but continuous soot tracks form between the foot points of the fuse wire creating a closed circuit to the fault
Solution Approach 1:
The fuse wire is segmented into multiple sections along its length, with alternating sections in physical contact with and without physical contact with the solid electrical insulation system. This segmentation prevents the formation of continuous soot tracks while maintaining current limiting functionality.
Solution Approach 2:
Different sections of the fuse wire have different local properties: some sections are in physical contact with the solid electrical insulation system while others are not. This local variation in contact quality ensures that soot tracks formed during fuse operation are discontinuous, breaking the conductive path that would otherwise form a closed circuit.
2Temperature
If fuse wires are completely immersed in dielectric liquid for cooling, then arc quenching is effective, but soot residues can form continuous conductive paths between fuse foot points
Solution Approach 1:
The fuse wire structure is segmented with alternating contact sections, creating discontinuous soot tracks even when immersed in dielectric liquid. The segmentation breaks the potential continuous conductive path that would form from complete immersion.
Solution Approach 2:
The solid electrical insulation system acts as an intermediary structure that the fuse wire alternately contacts and avoids. This intermediary creates physical discontinuities in the soot track formation path, preventing continuous conductive paths while allowing the dielectric liquid to provide cooling.
3Adaptability or versatility
If the capacitor interior is pressurized to hydrostatic pressure level for subsea application, then the capacitor can operate at depth, but arc behavior changes and open circuit after current limiting operation cannot be guaranteed
Solution Approach 1:
The segmented fuse wire design with alternating contact sections creates discontinuous soot tracks that prevent closed circuit formation, ensuring reliable open circuit behavior even under high-pressure subsea conditions where arc behavior differs from atmospheric conditions.
Solution Approach 2:
The varying local contact properties along the fuse wire create regions with different soot deposition characteristics. This local quality variation ensures that even when arc behavior changes under pressure, the soot tracks remain discontinuous, maintaining open circuit formation reliability.
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 reduces the risk of closed circuit formation during capacitor element failures, ensuring reliable operation under high-pressure conditions by maintaining a discontinuous soot track and effective arc quenching, thus preventing damage to remaining capacitor elements.
Implementation Method 1
the arc created by the operated fuse can expand and be cooled and extinguished by the surrounding insulating materials... Due to the good cooling properties of oil, this arc is quenched within a few tens to hundreds of microseconds
Implementation Method 2
the operated fuse can interrupt the discharge before all parallel energy is dumped into the short circuit spot... In case of a capacitor element failure, the large discharge current leads to the evaporation of the fuse
Data Source
AI summary
A power capacitor unit for high-pressure applications is provided. The power capacitor unit includes a housing, a plurality of capacitor elements connected to each other and arranged inside the housing, a dielectric liquid (L), a solid electrical insulation system arranged to electrically insulate each capacitor element, a busbar, a plurality of fuse wires, each fuse wire having a first end connected to a respective capacitor element and a second end connected to the busbar (B), wherein the capacitor elements, the solid electrical insulation system, and the fuse wires are immersed in the dielectric liquid (L). Each fuse wire has a plurality of first sections that are in physical contact with the electrical insulation system, and wherein each fuse wire has a plurality of second sections without physical contact with the solid electrical insulation system.