Tension Sensor for Electrified Fence Using Spring Thresholds
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Solution Overview
Problem
Existing systems for detecting changes in wire tension in electrified fences are either expensive or can be overcome by intruders using insulating materials, and they fail to differentiate between normal variations and attempted breaches.
Innovation Solution
A tension sensor with first and second contacts and a biasing structure that maintains electrical connectivity below a predetermined tension level, breaking connectivity when the tension exceeds this value, using a combination of springs with different spring constants to detect and signal tension changes indicative of breaches.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If electronic arrangements such as strain gauges are used to monitor wire tension, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent extracts the monitoring function from complex electronic systems and implements it using the existing energizer's monitoring capacity. The tension sensor uses simple electrical continuity detection through contacts and biasing structures, eliminating the need for expensive strain gauges while maintaining effective tension monitoring through the energizer's built-in capabilities
Solution Approach 2:
The system uses the energizer's own monitoring capacity to detect tension changes, making the existing system serve dual purposes: energizing the fence and monitoring tension. This eliminates the need for separate expensive monitoring equipment while utilizing resources already present in the system
2Reliability
If a loop device is used to detect wire parting, then reliability is improved, but ease of operation deteriorates due to insulating material countermeasures
Solution Approach 1:
The patent introduces a tension sensor as an intermediary device that detects tension changes through electrical continuity monitoring. This mediator provides reliable breach detection without requiring direct contact with wires that could be insulated, as it monitors the mechanical state of wires through electrical contacts that respond to tension-induced position changes
Solution Approach 2:
The patent replaces mechanical loop devices with electrical continuity-based tension sensing. Instead of relying on mechanical contact between loops and wires that can be defeated by insulation, the system uses electrical contacts and biasing structures that detect wire position changes through electrical circuit continuity, providing more reliable detection that cannot be easily circumvented
3Measurement precision
If tension monitoring is implemented to detect all tension changes, then measurement precision is improved, but loss of information increases due to false alarms from normal variations
Solution Approach 1:
The patent uses biasing structures with springs that are calibrated to specific force values, creating a threshold-based detection system. Normal tension variations within acceptable ranges do not trigger alarms, while significant tension changes indicative of breaches do. This parameter-based thresholding filters out false alarms while maintaining detection sensitivity for actual threats
Solution Approach 2:
The system monitors tension continuously but only triggers alarms for excessive tension changes beyond predetermined thresholds. This partial action approach avoids responding to every minor fluctuation, selectively activating the alarm function only when tension changes exceed normal operational variations, thereby reducing false alarms while maintaining security
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
Effectively differentiates between normal tension variations and breach attempts, allowing for alarm activation only when the tension exceeds a predetermined value, thus enhancing security without false alarms from environmental factors like temperature or vegetation.
Implementation Method 1
a biasing structure which is responsive to a tension level in a taut wire and which maintains the contacts electrically connected to each other with said tension level below a predetermined value and which breaks electrical connectivity between the contacts if said tension level is above said predetermined value
Data Source
AI summary
A tension sensor for an electrified fence which includes two contacts and a spring arrangement which, in response to a tension level in a taut wire in the electrified fence keeps the contacts electrically connected to each other when the tension level is below a predetermined value and which breaks such electrical connectivity when the tension level exceeds the predetermined value.