Fault-Managed DC Power Cable with Impedance Fault Detection
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Solution Overview
Problem
As power levels in Power over Ethernet (PoE) and Power and Fiber Cable (PFC) applications increase, there is a need to ensure that the energy provided during a fault is limited to prevent electrical shocks and ensure user safety.
Innovation Solution
A fault managed power system is implemented, which includes an upstream low-pass filter, an impedance sensor tank circuit, and upstream switches to detect electrical disturbances on the power cable, interrupting the supply of electrical energy in case of a fault, such as human body contact, using a controller to manage the flow of electrical pulses and DC current/voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If power levels in PoE and PFC applications are increased to meet growing demand for smart building services, then power delivery capability is improved, but the risk of electrical shock and energy provided into faults increases
Solution Approach 1:
The system performs preliminary fault detection by monitoring cable impedance characteristics before full power is applied. The controller detects faults during a detection phase and only allows power delivery when no faults are present, preventing electrical shock hazards while maintaining high power delivery capability when safe
Solution Approach 2:
The patent introduces an intermediary detection and control system between the power source and the cable. This intermediary monitors cable impedance, detects faults, and controls power delivery through switching elements, thereby mediating between high power delivery requirements and electrical safety concerns
2Power
If power levels are increased to 100W or higher to support advanced devices, then device functionality is improved, but the energy provided during faults exceeds safe levels
Solution Approach 1:
The system performs preliminary fault detection by monitoring cable impedance characteristics before full power is applied. The controller detects faults during a detection phase and only allows power delivery when no faults are present, preventing electrical shock hazards while maintaining high power delivery capability when safe
Solution Approach 2:
The patent introduces an intermediary detection and control system between the power source and the cable. This intermediary monitors cable impedance, detects faults, and controls power delivery through switching elements, thereby mediating between high power delivery requirements and electrical safety concerns
3Reliability
If continuous power monitoring and fault detection systems are implemented, then safety is improved, but system complexity increases
Solution Approach 1:
The system uses a multi-functional controller that performs both fault detection and power management functions. The same controller that manages power delivery also monitors cable impedance and detects faults, eliminating the need for separate dedicated detection hardware and reducing overall system complexity
Solution Approach 2:
The system uses the existing power cable and controller infrastructure to perform self-diagnosis through impedance monitoring. The controller automatically detects faults using the cable's own electrical characteristics without requiring external testing equipment, making the system self-monitoring and self-protecting
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 limits energy during faults, providing touch-safe levels and enhancing shock and fire safety while allowing for efficient power delivery and powerline communication.
Implementation Method 1
an upstream low-pass filter, connected between an electrical power supply and the power cable, for isolating the power cable from upstream noise or signals
Implementation Method 2
The downstream component(s) can include a downstream low-pass filter for isolating the power cable from downstream noise or signals
Implementation Method 3
a sensor including an impedance sensor tank circuit for measuring electrical activity related to the electrical pulses on the power cable
Implementation Method 4
A capacitor in the impedance sensor and inductor in the pi-filter can form the tank circuit to amplify a fault signal on the cable
Data Source
Figure 1A
Figure 1B
Figure 1C
AI summary
A fault managed power method and system are provided, which includes a source, downstream component(s) and a power cable for delivering electrical energy, including electrical pulse(s) or DC current/voltage and electrical pulse(s), from the source to the downstream component(s). The cable is isolated from upstream and downstream noise or signals using low-pass filters, which are arranged upstream and downstream of the power cable. The method and system can measure electrical activity on the cable using an impedance sensor tank circuit; detect for an electrical disturbance on the cable corresponding to an occurrence of a fault resulting from body contact with the cable or other faults, based on the measurements from the sensor, when the pulses or the DC current/voltage and pulses are supplied to the cable; and in response to detection of the occurrence of the fault, interrupt the supply of electrical energy to the cable, via an upstream switch(es).