Plasma-Tube DC Cutoff Circuit for Arc-Free Fault Interruption
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Solution Overview
Problem
Existing high DC voltage cut-off devices face challenges in efficiently interrupting electric currents due to the establishment of electric arcs, which leads to erosion and ionization, requiring costly and restrictive maintenance. Additionally, these devices struggle with interrupting low-intensity fault currents and suffer from electrical losses during nominal operation.
Innovation Solution
A cut-off device for high DC voltage that generates a counter-current through the main apparatus using energy stored in a changeover capacitor, featuring a plasma tube switch and a control system supplied by the changeover capacitor, to facilitate the extinction of electric arcs and ensure efficient current interruption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a mechanical switch element is used to cut off high DC current, then the device structure is simple, but electric arc is established causing erosion and ionization requiring costly maintenance
Solution Approach 1:
The patent introduces a plasma tube as an intermediary component between the mechanical switch and the high DC current. The plasma tube generates a counter-current that extinguishes the electric arc formed by the mechanical switch, preventing erosion and ionization damage. This mediator resolves the contradiction by allowing the simple mechanical switch structure to function without the harmful effects of direct arc contact.
Solution Approach 2:
The patent replaces the purely mechanical arc-extinguishing mechanism with a plasma-based electromagnetic system. Instead of relying on mechanical separation alone, the system uses a plasma tube to generate a counter-current that actively extinguishes the arc, substituting mechanical action with a controlled plasma discharge process that reduces erosion and maintenance requirements.
2Device complexity
If a mechanical cut-off apparatus is used for high DC current, then the device is simple, but current interruption is difficult under high DC conditions
Solution Approach 1:
The patent applies preliminary anti-action by generating a counter-current through the plasma tube before the mechanical switch completes its opening. This counter-current acts in opposition to the fault current, preparing to extinguish the arc as soon as the mechanical contacts separate, thereby ensuring reliable current interruption even under challenging high DC conditions.
Solution Approach 2:
The plasma tube serves as an intermediary that bridges the gap between the simple mechanical switch and the requirement for reliable current interruption. It provides the additional plasma-based mechanism needed to ensure arc extinction and current break, making the overall system reliable while maintaining relative simplicity.
3Productivity
If energy is stored in changeover capacitor for counter-current generation, then current interruption efficiency is improved, but device complexity increases
Solution Approach 1:
The patent implements preliminary action by pre-charging the changeover capacitor before the fault occurs. The capacitor is charged during normal operation and then discharged through the plasma tube when needed to generate the counter-current. This preliminary energy storage improves interruption efficiency while keeping the control system relatively simple, as the capacitor is passively charged and only requires triggering for discharge.
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 proposed solution effectively interrupts electric currents under high DC voltage without generating electrical losses during nominal operation, reduces arc duration and associated erosion, and enables current interruption regardless of fault current intensity.
Implementation Method 1
a plasma tube switch and a control system supplied by the changeover capacitor, to facilitate the extinction of electric arcs
Implementation Method 2
the establishment of electric arcs, which leads to erosion and ionization
Implementation Method 3
energy stored in a changeover capacitor
Data Source
AI summary
A DC high voltage cut-off device includes at least one cut-off module, having: a main cut-off apparatus in a main branch, a general surge protector in an absorption branch, and a changeover branch, with at least one changeover capacitor wherein: a first plasma tube switch in the changeover branch, a pre-charge circuit of the changeover capacitor, a changeover surge protector, in parallel with the changeover capacitor, and having a protection voltage lower than a nominal operating voltage of the cut-off module and, by at least one pilotable switch which supplies the first plasma tube switch with a voltage derived from an electric voltage between the armatures of the changeover capacitor.