PoE Power Sourcing Equipment Temperature Control via Cable Resistance
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Solution Overview
Problem
Power-over-Ethernet (PoE) systems face challenges in detecting and preventing cable overheating, as existing methods like infrared detection circuits are limited in accuracy and safety, and may not detect temperature increases within the cable conductors, potentially leading to catastrophic events such as insulation melting or fires.
Innovation Solution
A method within power-sourcing equipment (PSE) that controls power delivery based on temperature change results determined from resistance measurements using the temperature coefficient of the cable conductor material, allowing for accurate temperature measurement and proactive power adjustment to prevent overheating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an infrared detection circuit is used to monitor cable temperature, then temperature monitoring capability is provided, but measurement precision is insufficient because it only detects external cable surface temperature rather than internal conductor temperature
Solution Approach 1:
The patent replaces the infrared optical detection system with an electrical resistance-based temperature sensing system. By measuring the DC resistance of the cable conductors and using the known temperature coefficient of copper, the system directly calculates internal conductor temperature without needing external thermal radiation detection, thereby achieving precise internal temperature measurement while simplifying the detection mechanism
Solution Approach 2:
The patent introduces DC resistance measurement as an intermediary parameter to infer temperature. Instead of directly measuring temperature, the system measures electrical resistance (which changes predictably with temperature) and converts this measurement into temperature information using the temperature coefficient, providing accurate indirect temperature sensing
2Reliability
If infrared camera scanning is used to detect cable temperature, then temperature monitoring is achieved, but reliability is insufficient due to limited scanning coverage and environmental obstructions
Solution Approach 1:
The patent enables the cable itself to serve as the sensing element. The cable's inherent electrical resistance property is utilized to detect its own temperature condition. By measuring the resistance of the cable conductors directly at the PSE, the system achieves continuous, complete coverage monitoring without requiring external cameras or manual intervention, thereby improving reliability and ease of operation
3Measurement precision
If temperature sensors are embedded within cable bundles, then accurate temperature measurement is achieved, but device complexity and installation difficulty increase significantly
Solution Approach 1:
The patent makes the existing power delivery infrastructure multi-functional. The same cable that delivers power also serves as the temperature sensing element through its resistance property. The PSE equipment that already exists for power delivery is enhanced to also perform temperature monitoring functions, eliminating the need for separate embedded sensors and reducing installation complexity
Solution Approach 2:
The patent extracts the temperature sensing function from the physical cable structure and relocates it to the PSE's control circuitry. Instead of embedding sensors in the cable, the system uses the cable's electrical properties and performs temperature calculation electronically at the power sourcing equipment, separating the sensing function from the cable's physical structure
4Measurement precision
If DC resistance measurements are used to determine temperature, then measurement precision is improved, but loss of energy increases due to continuous current monitoring requirements
Solution Approach 1:
The patent implements periodic resistance measurements rather than continuous monitoring. The PSE periodically checks the DC resistance of the cable conductors during normal operation and uses these periodic measurements to track temperature changes. This approach maintains measurement precision while significantly reducing energy consumption compared to continuous monitoring, as the resistance measurements are taken at intervals rather than continuously
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 provides a reliable and convenient means to accurately predict and prevent cable overheating, ensuring safe operation by enabling, scaling back, or disabling power delivery to a remotely powerable device, thus avoiding damage to the PoE infrastructure and surrounding environment.
Implementation Method 1
generating temperature change results determined from resistance measurements (e.g., using the temperature coefficient of the cable conductor material)
Implementation Method 2
generating a resistance value representing a resistance between the power-sourcing equipment and the remotely powerable device based on a voltage and a current
Data Source
AI summary
An improved method is performed within power-sourcing equipment. The method controls delivery of power to a remotely powerable device through a communications pathway that connects the power-sourcing equipment to the remotely powerable device. The method involves obtaining an initial resistance value representing an initial resistance of the communications pathway, and obtaining an operating resistance value representing an operating resistance of the communications pathway after obtaining the initial resistance value. The method further involves generating a temperature change result based on the initial resistance value and the operating resistance value, and selectively one of enabling, scaling back and disabling delivery of power to the remotely powerable device through the communications pathway based on the temperature change result.