Leakage Current Detection Line Open Circuit Fault Monitoring
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Solution Overview
Problem
Conventional leakage current detection and interruption (LCDI) devices cannot reliably determine if the leakage current detection line is an open circuit, which can lead to loss of protection function and safety threats, as they only test the internal circuit and trip mechanism without verifying the external leakage current detection line's integrity.
Innovation Solution
An LCDI device with a leakage current detection module, drive module, and test module that includes a solenoid, rectifier bridge, and semiconductor switch element to detect both leakage and open circuit faults, automatically disconnecting power when an open circuit is detected in the leakage current detection line, ensuring continuous safety monitoring.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional LCDI devices only test internal circuit and trip mechanism, then the device structure is simple, but the reliability of leakage current detection is insufficient because the external leakage current detection line integrity cannot be verified
Solution Approach 1:
The patent implements a feedback mechanism by detecting the voltage signal across the leakage current detection line through the test switch. When the detection line is intact, the voltage signal remains below a threshold; when open-circuited, the voltage signal exceeds the threshold, triggering the solenoid to open the reset switch. This feedback loop enables automatic verification of detection line integrity without adding complex external monitoring systems.
Solution Approach 2:
The device performs self-diagnosis of the leakage current detection line integrity using its own internal components. The test switch, in series with the leakage current detection line, allows the device to self-test the continuity and functionality of the detection line during normal operation, eliminating the need for separate external testing equipment or complex diagnostic circuits.
2Ease of operation
If manual testing of leakage current detection line is required, then the device complexity is reduced, but the ease of operation deteriorates because users must periodically operate test switches and cannot automatically determine detection line status
Solution Approach 1:
The device automatically monitors the integrity of the leakage current detection line without requiring user intervention. The test switch is continuously connected in series with the detection line, enabling the device to autonomously detect open-circuit conditions and trigger protective actions, freeing users from manual testing requirements while maintaining operational simplicity.
Solution Approach 2:
The system provides continuous feedback on the detection line status through automatic voltage monitoring. When the detection line becomes open-circuited, the feedback mechanism immediately detects the voltage change and triggers the solenoid to open the reset switch, providing real-time status information without requiring user action or interpretation.
3Measurement precision
If the test switch is added to enable detection line testing, then the measurement precision of detection line integrity is improved, but the device complexity increases due to additional components and circuit connections
Solution Approach 1:
The test switch is merged into the existing circuit architecture as a series connection with the leakage current detection line, combining the testing function with the existing detection pathway. This integration allows the test switch to serve dual purposes: enabling normal leakage current detection while simultaneously providing open-circuit detection capability, thereby improving measurement precision without proportionally increasing device complexity.
Solution Approach 2:
The test switch serves multiple functions within the circuit: it enables normal leakage current detection operation, provides open-circuit detection capability, and works in conjunction with the solenoid and reset switch to implement automatic protective actions. This multi-functionality allows a single component to improve measurement precision across multiple detection scenarios without requiring separate dedicated testing circuits.
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 device effectively detects open circuit faults in the leakage current detection line, preventing power supply disconnection and ensuring the device's functionality, thereby enhancing safety by automatically monitoring and addressing potential open circuit issues.
Implementation Method 1
a solenoid; a rectifier bridge, coupled between the first and second power supply lines, configured to supply a working current to the solenoid
Data Source
AI summary
A leakage current detection and interruption (LCDI) device for power cord, and power connector and appliance employing the same. The LCDI device includes a switch module coupled on the power supply lines to control electrical connection between input and output ends of the device; a leakage current detection module including a leakage current detection line, for detecting a leakage current on the power supply lines and outputting a leakage current fault signal accordingly; a drive module, for driving the switch module to disconnect the electrical connection in response to the leakage current fault signal and/or an open circuit fault signal, the open circuit fault signal representing an open circuit condition of the leakage current detection line; and a test module including a test switch, coupled to the leakage current detection module, where the leakage current detection module outputs the leakage current fault signal when the test switch is closed.