Gas Discharge Tube DC Circuit Breaker with Control Grid
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Solution Overview
Problem
Direct current (DC) circuit breakers face challenges in interrupting current due to the absence of zero-crossings in DC systems, leading to increased arcing risks and reduced effectiveness, particularly in high-voltage systems where existing solutions are physically large and have slow response times.
Innovation Solution
A DC circuit breaker utilizing a gas discharge tube with a thermionic cathode and control grid, coupled with an extinguishing path, which conducts and interrupts load current through a normal current path, and directs energy dissipation over a controlled period to manage break times, eliminating the need for a parallel commutation path.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If conventional electromechanical contactors are used in medium- and high-voltage DC systems, then current interruption can be achieved, but the device size becomes physically large and response time increases to over 1 millisecond
Solution Approach 1:
The patent replaces the conventional electromechanical contactor system with a gas discharge tube system. The gas discharge tube uses gas ionization and plasma formation to achieve current interruption without moving mechanical parts. This substitution eliminates the mechanical inertia and contact wear problems, achieving microsecond-level response times while reducing device size and increasing power density.
Solution Approach 2:
The patent changes the operating parameters by using controlled gas ionization instead of mechanical contact separation. By controlling the gas pressure, electrode geometry, and applied voltage, the system achieves rapid current interruption. The extinguishing path further controls the arc duration and energy dissipation, optimizing both speed and size parameters simultaneously.
2Reliability
If DC current interruption is attempted without zero-crossing assistance, then circuit breaker functionality is maintained, but arcing risk increases and effectiveness decreases
Solution Approach 1:
The patent converts the harmful DC arc into a controlled and beneficial plasma state. By using a gas discharge tube with controlled gas ionization, the arc is contained and managed rather than suppressed. The plasma channel provides a controlled path for current interruption, and the extinguishing path further manages the arc energy dissipation, transforming the harmful arcing effect into a reliable current breaking mechanism.
Solution Approach 2:
The patent introduces gas as an intermediary medium between the electrodes. The gas ionizes to form plasma, which acts as a controlled conductor during the switching process. This intermediary plasma state allows for controlled current transfer and interruption, reducing direct arc contact between electrodes and thereby reducing harmful arcing effects while maintaining reliable current breaking capability.
3Productivity
If parallel normal current and commutation paths are used, then current diversion is enabled, but the device becomes physically large and slower
Solution Approach 1:
The patent merges the normal current path and commutation path into a single gas discharge tube structure. The gas discharge tube inherently provides both normal conduction and commutation functions through controlled gas ionization and deionization. This merging eliminates the need for separate parallel paths, reducing device complexity and increasing power density while maintaining the required current diversion capability for effective breaking.
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 enables faster and more efficient current interruption with reduced parasitic losses and increased power density, accommodating high-voltage systems while minimizing arcing risks and response time, thus enhancing the service life and effectiveness of DC circuit breakers.
Implementation Method 1
The gas discharge tube includes a thermionic cathode, an anode, and a control grid
Implementation Method 2
The gas is configured to insulate the thermionic cathode from the anode
Implementation Method 3
The control grid is configured to generate an electric field to establish a conductive plasma between the thermionic cathode and the anode
Implementation Method 4
generate an electric field to establish a conductive plasma between the thermionic cathode and the anode
Implementation Method 5
dissipating energy inductively stored in the electrical system into the extinguishing path over a controlled period of time
Data Source
AI summary
A DC circuit breaker includes a gas discharge tube (GDT) coupled in parallel with an extinguishing path. The GDT conducts and interrupts a load current through a normal current path. The GDT includes a thermionic cathode, an anode, and a control grid. The control grid is configured to regulate opening and closing of the normal current path. The extinguishing path is configured to lengthen a break time for the DC circuit breaker.