Gas-Insulated Disconnector Arc Confinement for SF6-Free Switching
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Solution Overview
Problem
Gas-insulated substations using the 'g3' gas face issues with powder generation during disconnector operation, which affects dielectric strength, and lack a solution to reduce arc duration and misalignment problems, particularly during Bus Transfer Current Switching (BTCS) and Bus Charging Current Switching (BCCS), leading to wear and environmental concerns.
Innovation Solution
A disconnector design featuring a pair of arcing contacts with an insulating part and ring that confines the arc within a limited volume, using a V-shaped or restricted insulating ring and a concave arcing contact shape to reduce gas decomposition and arc duration, while maintaining alignment to ensure homogeneous arc formation and reduced wear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If g3 gas is used to replace SF6, then environmental impact is reduced, but powder is generated during circuit-breaker opening which harms dielectric strength
Solution Approach 1:
The patent divides the gas-insulated disconnector into separate functional zones: a main contact chamber for current carrying and an arcing chamber for arc containment. The arcing chamber is further segmented with insulating parts and insulating rings to create a limited volume that confines the arc and its decomposition products, preventing powder from contaminating the main contact chamber and preserving dielectric strength.
Solution Approach 2:
The patent introduces insulating parts and insulating rings as intermediary elements between the arc and the main gas volume. These intermediaries physically separate the arc-generated powder from the bulk gas, allowing the use of environmentally friendly g3 gas while preventing powder contamination from degrading dielectric strength in the main contact areas.
2Duration of action of moving object
If arc duration is reduced to limit gas decomposition, then powder generation is reduced, but switching capabilities are affected
Solution Approach 1:
The patent segments the switching function into two distinct chambers: the main contact chamber handles current interruption with longer arc duration necessary for switching capabilities, while the arcing chamber with limited volume confines the arc and its products, reducing overall gas decomposition. This segmentation allows each chamber to be optimized for its specific function without compromising the other.
3Duration of action of moving object
If opening speed is increased to reduce arc duration, then arc decomposition is reduced, but zero current crossings are reduced and wear increases
Solution Approach 1:
The patent separates the opening operation into two phases occurring in different chambers: the main contacts open first in the main contact chamber at normal speed to maintain proper timing and wear characteristics, while the arcing contacts subsequently open in the confined arcing chamber where the limited volume naturally restricts arc duration and gas decomposition regardless of opening speed.
4Reliability
If misalignment of arcing contacts is corrected to ensure homogeneous arc, then wear is reduced, but device complexity increases
Solution Approach 1:
The patent isolates the arcing contacts and their alignment requirements to a separate arcing chamber, independent of the main contact chamber. This segmentation allows the arcing contacts to be precisely aligned within their confined space without affecting the main contact assembly, reducing the overall complexity by decoupling the alignment requirements of different contact systems.
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 effectively confines the arc, reducing gas decomposition and arc duration by up to 75%, and ensures homogeneous arc formation and reduced wear, addressing the limitations of existing disconnectors in gas-insulated substations.
Implementation Method 1
When the arcing contacts separate, they form, together with the insulating part and the insulating ring, a limited volume which contains a limited quantity of gas. Thus, only a limited quantity of gas can be decomposed by the arc.
Data Source
AI summary
The invention concerns a disconnector (100) for a GIS comprising:a pair of permanent contacts (24, 41), one (24) fixed and the other one (41) movable along an axis (AA′), called the axis of the disconnector;a pair of arcing contacts (22, 42), one (22) fixed and the other one (42) movable;an insulating part (52) located inside said fixed arcing contacts (22, 42), and means (50) for pressing said insulating part against a front surface of the movable arcing contact (42);an insulating ring (56) located at the outlet of the fixed arcing contact (22).