Circuit Interrupter Over-Temperature Protection
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Solution Overview
Problem
Existing electrical devices for household use, such as leakage current detection interrupters (LCDI) and arc fault circuit interrupters (AFCI), lack self-testing capabilities, leading to safety concerns when the leakage current detection wire breaks or key components overheat, potentially causing fires due to continued use despite lost protection functions.
Innovation Solution
A low-cost and reliable circuit interrupter device with a temperature-controlled module and leakage current detection unit that automatically disconnects the power source when a leakage current, open current-carrying wires, or excessive temperature is detected, utilizing a temperature-sensitive switch and switching control circuit to ensure safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If leakage current detection function is provided in power cords, then safety is improved, but the device cannot detect when the detection wire breaks leading to false sense of security
Solution Approach 1:
The patent implements a self-testing feedback mechanism where the leakage current detection wire serves dual purposes: detecting actual leakage currents and testing its own integrity. The control circuit monitors the state of the detection wire through feedback signals, enabling the device to detect when the wire breaks and automatically trip the circuit breaker, preventing false sense of security.
Solution Approach 2:
The leakage current detection wire performs self-testing functionality by being part of the detection circuit itself. The system uses its own detection wire to test its own integrity, eliminating the need for separate testing mechanisms and enabling automatic detection of wire breakage.
2Object-affected harmful factors
If over-temperature protection is added to detect component heating, then fire hazard protection is improved, but device complexity increases
Solution Approach 1:
The patent merges the over-temperature protection function with the existing leakage current detection circuitry. The temperature-controlled switch is integrated into the same control circuit that handles leakage current detection, allowing both functions to share common components and signal processing paths, thereby minimizing additional complexity.
Solution Approach 2:
The control circuit is designed with multi-functionality, serving both leakage current detection and over-temperature protection functions. The same control circuit processes signals from both the leakage current detection wire and the temperature-controlled switch, enabling a single circuit to perform multiple safety functions.
3Reliability
If automatic self-testing capability is implemented, then reliability is improved, but manufacturing cost increases
Solution Approach 1:
The system achieves self-testing capability using existing components rather than adding dedicated testing mechanisms. The leakage current detection wire and control circuit work together to automatically test the integrity of the detection wire, eliminating the need for expensive separate testing devices or complex diagnostic systems.
Solution Approach 2:
The control circuit performs multiple functions including leakage current detection, self-testing of the detection wire, and coordination with the temperature-controlled switch. This multi-functionality reduces the need for separate dedicated circuits for each function, thereby lowering overall manufacturing costs while maintaining reliability.
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 solution provides enhanced safety by automatically disconnecting power when leakage current or over-temperature conditions are detected, preventing potential fires and ensuring the appliance's safety and the integrity of the electrical grid.
Implementation Method 1
a temperature controlled module having at least one temperature controlled switch disposed on a device under measurement, the temperature controlled switch being coupled between the leakage current detection wire and a phase wire or neutral wire
Data Source
AI summary
A power cord having a circuit interrupter such as a leakage current detection interrupter (LCDI) or arc fault circuit interrupter (AFCI), with a detection signal conductor wire in addition to the current carrying wires between the source and the load, and a temperature controlled switch coupled to the detection signal conductor wire on the load side. The temperature controlled switch is affixed to a device under measurement which is associated with the load, and changes its open or closed state when the device overheats. This in turn changes the state of the current flowing in the detection signal conductor wire. In response thereto, the circuit interrupter, which is coupled to the detection signal conductor wire on the source end, interrupts the power supply to the load.