Contactor Arc Fault Detection via Dual-Stage Verification
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Solution Overview
Problem
Conventional protection methods for electrical networks, such as thermal circuit breakers, are not reliable in detecting arc faults, especially in high-voltage environments like aeronautics, leading to potential fires and operational degradations due to high false alarm rates and untimely tripping.
Innovation Solution
A method and device that utilize a contactor to detect a first type of signal indicative of an electrical fault, temporarily open the circuit to verify the presence of a second type of signal characteristic of the fault, ensuring the circuit remains closed or open based on the verification, thereby minimizing damage and preventing fires without interrupting essential electrical equipment operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional protection means (thermal circuit breakers) are used to protect against arc faults, then the network is provided with basic protection, but the protection is not reliable and generates high false alarm rates
Solution Approach 1:
The detection process is segmented into two distinct phases: a first detection phase that triggers contactor opening upon detecting a first type of signal, and a second verification phase that checks for a second type of signal during a predetermined duration. This segmentation allows the system to differentiate between actual arc faults and false alarms, thereby improving reliability while reducing false alarm rates.
Solution Approach 2:
The system performs a preliminary detection action by opening the contactor when the first type of signal is detected, then verifies the fault before maintaining the open state. This preliminary action allows the system to prepare for potential fault isolation while avoiding premature permanent tripping, thus reducing false alarms while maintaining protection reliability.
2Reliability
If arc fault detection means are implemented in high-voltage environments, then arc faults can be detected, but the system experiences untimely tripping and operational degradations
Solution Approach 1:
The system opens the contactor as a preliminary measure when an arc fault is detected, then verifies the fault by checking for the second type of signal during a predetermined duration. Only after confirmation does the system maintain the open state, preventing untimely tripping while ensuring rapid response to genuine faults, thus preserving operational continuity.
Solution Approach 2:
The system applies partial action by temporarily opening the contactor for verification rather than immediately maintaining the open state. This partial measure allows the system to test the validity of the fault detection without fully committing to fault isolation, thereby avoiding unnecessary operational interruptions while maintaining protection capability.
3Speed
If the contactor is opened immediately upon detecting an arc fault signal, then the network is protected rapidly, but false alarms cause unnecessary operational interruptions
Solution Approach 1:
The fault isolation process is segmented into two stages: rapid contactor opening upon first signal detection, followed by verification through second signal detection during a predetermined duration. This segmentation enables the system to act quickly while maintaining accuracy, as the verification stage filters out false alarms before permanent isolation occurs.
Solution Approach 2:
The contactor opening is performed as a preliminary action rather than a final decision. The system then verifies the fault condition during a predetermined duration before maintaining the open state, allowing rapid initial response while ensuring detection accuracy through subsequent verification.
4Reliability
If verification duration is extended to reduce false alarms, then detection accuracy improves, but system response time increases
Solution Approach 1:
The system optimizes the predetermined verification duration as a critical parameter, setting it to a value that provides sufficient time for second signal detection to filter false alarms, while remaining short enough to maintain rapid overall response. This parameter optimization balances detection accuracy with response time requirements.
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 approach allows for rapid and reliable detection and isolation of arc faults, reducing the risk of fires and maintaining system safety by distinguishing between actual faults and false alarms, meeting stringent standards for aeronautical applications.
Implementation Method 1
an electrical fault generating a first type of signal and a second type of signal different from the first type of signal
Implementation Method 2
An arc fault generates various physical phenomena, including an electrical signal, an acoustic wave, an electromagnetic disturbance and a light wave
Data Source
Figure 1~2
Figure 3~4
AI summary
The present invention primarily relates to a method for protecting a power grid (100) from an electrical fault, the electrical fault generating a first signal type and a second signal type that is different from the first signal type, the power grid (100) comprising an electrical power supply (110) and an electrical device (120) between which a contactor (133) is arranged, the contactor (133) being able to be placed in two states: - an open state (0), for which the electrical power supply (110) is not electrically connected to the electrical device (120); - a closed state (1), for which the electrical power supply (110) is electrically connected to the electrical device (120). The method is characterized in that it comprises the following steps: - detecting (210) a signal of the first type; - placing (220) the contactor in the open state (0); - verifying (230), during a predetermined time period referred to as "decided opening time (Tdod)", whether a signal of the second type appears; - keeping (240) the contactor in the open state (0) if a signal of the second type appears during the decided opening time (Tdod); placing (250) the contactor in the closed state (1) if no signal of the second type appears during the decided opening time (Tdod).