Active Arc Fault Breaker Using Pulsed Solid-State Detection
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Solution Overview
Problem
Existing arc fault circuit interrupters (AFCIs) face issues with nuisance tripping due to high costs and passive detection methods, limiting their widespread implementation despite proven fire risk reduction benefits.
Innovation Solution
A circuit breaker with solid-state components that uses active arc fault detection through power electronics, a current limiting resistor, and a sensing and control circuitry with a detection algorithm to monitor load current for arc-like signals, reducing nuisance tripping by switching on/off in short periods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If passive detection methods are used in traditional thermal-magnetic arc fault interrupters, then cost is reduced, but reliability of arc fault detection deteriorates due to nuisance tripping with noisy loads
Solution Approach 1:
The patent applies periodic action by using pulsed power electronics to actively modulate the circuit current at specific intervals. The system injects test signals periodically and analyzes the response to detect arc faults, transforming the continuous passive monitoring into discrete periodic active testing. This approach improves detection reliability while keeping power electronics usage limited to short pulses rather than continuous operation.
Solution Approach 2:
The patent uses an intermediary approach by introducing power electronics as a mediator between the circuit breaker and the load. These power electronics components act as an active test signal generator that injects modulated current into the circuit, allowing the sensing circuitry to detect arc faults through the response to these active signals rather than relying solely on passive current analysis.
2Reliability
If power electronics are continuously in the current path for active arc fault detection, then detection capability is improved, but cost increases due to requirement for high-grade components
Solution Approach 1:
The patent reduces component cost by using power electronics only during short periodic intervals for active detection rather than continuously. The pulsed operation allows the use of lower-grade power electronics components that can handle intermittent high-stress conditions without requiring expensive continuous high-power rated components, while still achieving effective arc fault detection during the active periods.
Solution Approach 2:
The system performs preliminary active detection by injecting test signals through the power electronics before a fault condition develops. The periodic active scanning allows the system to identify potential arc fault conditions in advance, and only activates full detection mode when anomalies are detected, reducing the overall stress and rating requirements for the power electronics components.
Data Source
AI summary
A circuit breaker for active detection of an arc fault is provided. It comprises a set of power electronics configured to make an arc fault detection active, a current limiting resistor in series with the set of power electronics and a sensing and control circuitry coupled to the set of power electronics and stores in a memory for execution a detection algorithm code with a detection logic. The sensing and control circuitry monitors a load current of at least one device connected to the circuit breaker, the sensing and control circuitry detects an arc-like signal in the load current, and by monitoring a change of the arc-like signal during a short on/off period of power electronics, the detection algorithm code can determine if there is an arc in the circuit.