Electronic Circuit Breaker Auto-Reset Without Temperature Drift
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Solution Overview
Problem
Existing circuit breakers, particularly those using Polymer Positive Temperature Coefficient (PPTC) auto-recovery fuses, are influenced by ambient temperature and lack an auto-recovery feature, necessitating replacement after overcurrent events, which is inefficient and unreliable.
Innovation Solution
A self-protective circuit breaker design incorporating a current sensing circuit, control circuit, comparison circuit, latch circuit, electric relay, and protective circuit that sets a threshold voltage and compares input voltage, allowing for automatic reset and protection against overcurrent without temperature dependence, using adjustable resistors and op-amp comparators to manage the relay's open and close states.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If PPTC auto-recovery fuses are used for overcurrent protection, then automatic reset capability is achieved, but performance becomes dependent on ambient temperature
Solution Approach 1:
The patent replaces the thermal-mechanical operation of PPTC fuses with an electronic control system. A microcontroller monitors current through sensing circuits and controls a solid-state switch (MOSFET or IGBT) to interrupt overcurrent. This electronic substitution eliminates temperature-dependent thermal expansion and melting mechanisms, providing automatic protection independent of ambient temperature conditions.
Solution Approach 2:
The patent introduces a microcontroller as an intermediary between the current sensing circuit and the power switch. This intermediary processes sensor data, compares it against predetermined thresholds, and intelligently controls the switching element. This intermediary layer enables precise current monitoring and automatic reset functionality without relying on temperature-sensitive materials.
2Reliability
If traditional fuses are used for overcurrent protection, then simple and reliable protection is provided, but manual replacement is required after operation
Solution Approach 1:
The patent implements a self-service protection system where the circuit breaker automatically detects overcurrent conditions, interrupts the circuit, and resets itself without human intervention. The microcontroller continuously monitors current levels, and when normal conditions resume, the system automatically recloses the circuit through the solid-state switch, eliminating the need for manual replacement or operation.
Solution Approach 2:
The patent enables the circuit breaker to recover and reuse its protective function indefinitely. Instead of being discarded like a blown fuse, the electronic components (microcontroller, solid-state switch, sensing circuits) can be reset and reused multiple times. The system recovers its protective capability by simply resetting the solid-state switch and continuing monitoring, providing sustainable protection without replacement.
3Extent of automation
If circuit breakers with motor operators are used for remote control, then automated operation is achieved, but device complexity and cost increase
Solution Approach 1:
The patent replaces mechanical motor operators with solid-state switching devices (MOSFETs or IGBTs) controlled by a microcontroller. This substitution eliminates mechanical moving parts, gears, and springs found in traditional motor-operated breakers. The solid-state switch provides the same circuit interruption function with electronic control signals, dramatically reducing mechanical complexity while maintaining or enhancing automation capabilities including remote control through digital communication interfaces.
Data Source
AI summary
A circuit breaker for protecting against a short circuit and over current. The circuit breaker includes a current sensing circuit configured to determine an input voltage. The circuit breaker also includes a control circuit configured to set a threshold voltage. The circuit breaker further includes a comparison circuit configured to compare the input voltage to the threshold voltage. The circuit breaker, in addition, includes a voltage output circuit configured to output an output voltage based on the comparison circuit.