Fault Current Limiter with Movable Sliding Contact
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Solution Overview
Problem
Existing fault current limiters in electrical grids require cooling liquids, leading to permanent energy losses and potential overheating during fault events, which can cause damage and necessitate rapid current interruption.
Innovation Solution
A fault current limiter arrangement that includes a movable electrical sliding contact part between the upper and movable electrical terminals of a vacuum circuit breaker unit, capable of switching between a short circuit and remote position to provide maximum electrical resistance without the need for cooling liquids, utilizing a mechanical actuator and contact spring unit for rapid resistance increase and current interruption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If cooling liquids are used to maintain superconductivity in fault current limiters, then the superconducting state can be maintained during normal operation, but permanent energy losses occur and overheating can happen during fault events
Solution Approach 1:
The patent removes the cooling liquid system entirely from the fault current limiter design. Instead of using liquid nitrogen or other cooling media to maintain superconductivity, the invention uses a solid-state superconducting material that maintains its superconducting state through its inherent critical temperature properties, eliminating the need for continuous cooling and the associated energy losses.
Solution Approach 2:
The patent replaces the mechanical cooling system (pumps, heat exchangers, cooling liquids) with an electrical field-based solution. The superconducting material's electrical properties change dramatically during fault conditions, naturally limiting current without requiring mechanical cooling intervention, thus substituting a mechanical system with an electrical field-based mechanism.
2Reliability
If high current flows through the fault current limiter during fault events, then the fault current is limited, but overheating and damage can occur
Solution Approach 1:
The patent utilizes the phase transition of the superconducting material from its superconducting state to a normal resistive state when the critical current is exceeded. During normal operation, the material remains in the superconducting state with zero resistance. During fault events, when current exceeds the critical value, the material transitions to a normal state with high resistance, automatically limiting the fault current without overheating, as the transition itself provides the protective function.
3Reliability
If a circuit breaker is arranged in line with the fault current limiter to interrupt current flow, then overheating and damage are avoided, but the device complexity increases
Solution Approach 1:
The patent combines the fault current limiting function and the circuit breaker function into a single integrated device. The superconducting material itself performs the current limiting function, and the device includes built-in detection and interruption capabilities, eliminating the need for separate external circuit breakers and reducing overall system complexity while maintaining protective functions.
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 solution eliminates energy losses associated with cooling liquids and provides a compact, efficient design that effectively limits fault currents without overheating, ensuring the safety and reliability of electrical grids by rapidly interrupting current flow during fault events.
Implementation Method 1
high-temperature superconductors can be well suited for use in a fault current limiter due to their property to lose superconductivity and transit from the non-resistive superconducting state to a normal state with high electric resistivity when at least one of the critical current, the critical temperature or the critical magnetic field of the superconductor material is exceeded
Implementation Method 2
the fault current limiter unit includes a movable electrical sliding contact part electrically arranged between the upper electrical terminal of the circuit breaker unit and the movable electrical contact of the circuit breaker unit, and which is movable between a short circuit position adjacent to the upper electrical terminal and a remote position from the upper electrical terminal for providing a maximum electrical resistance for the current flow
Data Source
AI summary
A fault current limiter arrangement for a low, medium and high voltage electricity grid, including a fault current limiter unit which is arranged in line with a circuit breaker unit including a fixed electrical contact which is connected to a lower electrical terminal and a movable electrical contact which is connected to an upper electrical terminal, in order to interrupt the current flow after the fault current limiter unit has limited the current flow in a detected fault event. The fault current limiter unit includes a movable electrical sliding contact part which is electrically arranged between the upper electrical terminal of the circuit breaker unit and the movable electrical contact of the circuit breaker unit, and which is movable between a short circuit position adjacent to the upper electrical terminal and a remote position far from the upper electrical terminal for providing a maximum electrical resistance for the current flow.