Aircraft Windshield Arc Detection Circuit
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Solution Overview
Problem
Existing sensors for detecting arcing in aircraft windshields are limited by their inability to accurately differentiate between current variations caused by arcing and electrical noise, leading to premature failure and reduced service life due to moisture ingress and delamination.
Innovation Solution
An electrical system comprising a temperature sensor, arc sensor, and filter-modifying system that monitors voltage and temperature, disconnecting power when predetermined arcing levels are detected to prevent overheating and arcing, ensuring accurate detection and prevention of damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If existing sensors measure current at bus bars to detect arcing, then arcing detection capability is provided, but electrical noise and interference from airplane generators cause inaccurate readings that cannot distinguish arcing from noise
Solution Approach 1:
A differential amplifier circuit serves as an intermediary to compare currents between two bus bars. The amplifier processes the current signals and produces a differential output that represents only the current difference between bus bars, effectively filtering out common electrical noise while preserving arcing detection capability
Solution Approach 2:
The system continuously monitors the differential current signal and provides feedback to a control system. When the differential signal exceeds a predetermined threshold, the control system responds by discontinuing current input to the bus bars, creating a closed-loop feedback mechanism that prevents false alarms from noise while reliably detecting actual arcing conditions
2Reliability
If the outboard moisture seal is provided to prevent moisture ingress, then moisture barrier function is achieved, but the seal fails due to cracking and de-bonding from wind and rain erosion over time
Solution Approach 1:
The arc detection system performs preliminary detection of arcing conditions before moisture ingress can cause delamination and seal failure. By detecting arcing early through accurate differential current measurement, the system can take preventive action to address electrical issues before they progress to physical damage of the moisture seal and windshield layers
Solution Approach 2:
The system converts the potentially harmful effect of electrical arcing into a detectable signal that triggers preventive action. By monitoring differential current between bus bars, the system identifies arcing conditions that would otherwise go undetected amidst electrical noise, allowing preventive maintenance before the arcing damages the moisture seal and windshield structure
3Object-affected harmful factors
If delamination occurs allowing moisture to move between layers, then moisture barrier function is compromised, but this accelerates degradation causing arcing and failure of bus bars and conductive coating
Solution Approach 1:
The differential current monitoring system performs preliminary detection of arcing conditions before moisture ingress and delamination can occur. By continuously comparing currents between bus bars and detecting imbalances that indicate arcing, the system identifies electrical problems in their early stages, allowing corrective action before moisture can penetrate and cause cascading failures
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 system effectively prevents overheating and arcing, extending the service life of aircraft windshields by accurately distinguishing between arcing and noise-induced current variations, thereby maintaining operational efficiency and reducing maintenance needs.
Implementation Method 1
an arc sensor for monitoring voltage of the electrically conductive member
Implementation Method 2
a temperature sensor for sensing the temperature of the electrically conductive member
Implementation Method 3
an electrical conductive member between and in electrical contact with the spaced bus bars to heat the outer surface of the windshield
Data Source
Figure 1~2
Figure 3
Figure 4
AI summary
An electrical system responsive to overheating and/or electric arcing of an electrically conductive member, e.g. a heating member of an aircraft windshield, includes a first switch in a first current path, and a second switch in a second current path. The first current path is from an electrical power supply through the first switch, through an arc sensor to the heating member to the power supply. The second current path is from a temperature sensor monitoring the temperature of the heating member through the second switch to a temperature controller. When the temperature of the heating member is at or above a predetermined value, the temperature controller causes the first switch to open. When there is arcing, the second switch is moved to the open position. The temperature controller senses that the second switch is open and causes the first switch to open.