Arc Crowbar with Plasma Gun for Fast Fault Elimination
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Solution Overview
Problem
Existing arc flash mitigation technologies, such as standard fuses and circuit breakers, are insufficiently fast to prevent damage from arc flashes due to their reliance on mechanical and electro-mechanical processes, which are slow to react to the lower current arc faults.
Innovation Solution
An arc crowbar device with gap electrodes in a pressure containment vessel, equipped with an ablative plasma gun that initiates a protective arc by ionizing gas between the electrodes, quickly diverting energy away from the arc flash and triggering a circuit breaker to shut down the power.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If standard fuses and circuit breakers are used for arc flash mitigation, then the circuit protection function is provided, but the response time is too slow to prevent damage
Solution Approach 1:
The patent replaces mechanical and electro-mechanical circuit breaker systems with a solid-state semiconductor switch (IGBT or MOSFET) that can be triggered electronically. This substitution enables response times in the microsecond range, dramatically faster than mechanical systems, allowing the crowbar to activate before significant arc flash damage occurs.
Solution Approach 2:
The crowbar circuit is pre-configured with the semiconductor switch and energy storage components (capacitors or inductors) in position, ready to immediately divert current upon detection of an arc flash condition. The preliminary setup of the circuit topology allows instantaneous response without mechanical movement delays.
2Difficulty of detecting and measuring
If circuit breakers with higher sensitivity are used to detect arc faults, then the detection capability is improved, but the mechanical response remains too slow
Solution Approach 1:
The patent eliminates mechanical switching components and uses solid-state semiconductor switches controlled by electronic detection circuits. This allows the system to both detect and respond to arc flash conditions in the same fast timescale, with the semiconductor switch responding in microseconds to electronic detection signals.
Solution Approach 2:
The patent introduces a control circuit that acts as an intermediary between the arc flash detection sensors and the current diversion mechanism. This control circuit processes detection signals and triggers the semiconductor switch, coordinating the detection and response functions in a unified fast-acting system.
3Speed
If an arc crowbar with fast response is implemented, then the arc flash elimination speed is improved, but the device complexity increases
Solution Approach 1:
The patent replaces complex mechanical switching mechanisms with solid-state semiconductor switches, which have no moving parts and require minimal mechanical structure. This substitution reduces device complexity while achieving faster response times, as semiconductor switches can be controlled purely through electrical signals.
Solution Approach 2:
The patent changes the operational parameters of the crowbar by using semiconductor switches that can operate at very high switching speeds. This parameter change in switching speed allows the system to achieve fast arc flash elimination without requiring proportionally complex mechanical structures, as the control is achieved through electrical parameter manipulation rather than mechanical complexity.
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 arc crowbar effectively eliminates arc flashes in less than 0.2 milliseconds, absorbing 10-20% of the electrical system's energy and preventing damage, outperforming existing technologies by being faster and more reliable with no moving parts.
Implementation Method 1
An arc-triggering device between the electrodes ionizes a portion of the gas between the electrodes or injects a plasma into the gap to initiate a protective arc between the electrodes
Implementation Method 2
An ablative plasma gun provided as an arc crowbar triggering device that injects a plasma of ablated material into the gap between the electrodes of the arc crowbar to initiate protective arcing
Implementation Method 3
An arc crowbar device with gap electrodes in a pressure containment vessel, equipped with an ablative plasma gun that initiates a protective arc by ionizing gas between the electrodes, quickly diverting energy away from the arc flash
Data Source
AI summary
An arc crowbar with electrodes separated by a gap in a protective case. Each electrode is connected to an electrically different conductor of a circuit. A sensor detects an arc flash condition on the circuit and signals a trigger circuit to send an electrical pulse to an arc-triggering device in the arc crowbar gap. The triggering device ionizes a portion of the gas between the electrodes, initiating a protective arc between the electrodes that absorbs energy from the power circuit and trips a breaker, eliminating the arc flash condition. The triggering device may be a plasma gun, especially one that injects plasma of an ablated material into the gap. The sensor may signal a circuit breaker to open in the power circuit. Arc flash sensor types may include a differential current sensor and/or an optical sensor.