Backup Timing Circuit for Microcontroller Circuit Breaker
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Microcontroller-based circuit breakers may fail to detect faults if the power supply regulator or the microcontroller itself is faulty, leaving the connected load unprotected.
Innovation Solution
The implementation of backup timing circuits that ensure the circuit breaker trips even if the microcontroller is unresponsive, either due to a power supply failure or a microcontroller fault, by using separate power supplies and configurations that bypass the microcontroller to activate the tripping mechanism.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the microcontroller is used as the primary fault detection mechanism, then sophisticated fault analysis is possible, but the circuit lacks a backup tripping function if the microcontroller fails to start up
Solution Approach 1:
A pin on the microcontroller is used as an intermediary signal between the microcontroller's startup status and the backup timing circuit. When the microcontroller successfully initializes, it drives this pin low to discharge the timing capacitor and prevent tripping. If the pin remains high-impedance (indicating microcontroller failure), the capacitor charges and triggers the tripping mechanism.
2Reliability
If a backup timing circuit is added to force tripping on microcontroller failure, then reliability is improved, but the device complexity increases
Solution Approach 1:
The backup timing circuit is designed to share common components with the primary control circuit, including the trip mechanism, power transformer, and certain passive components. This merging reduces the overall component count and complexity while maintaining the backup functionality. The timing circuit essentially piggybacks on existing infrastructure rather than creating entirely separate systems.
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
Ensures the circuit breaker trips promptly to protect the load from electrical faults, even in cases where the microcontroller fails to start up or its power supply is unresponsive, thereby maintaining safety and reliability.
Implementation Method 1
the node can build up a voltage across a capacitor that eventually becomes sufficient to energize the transistor
Data Source
AI summary
A circuit breaker capable of microcontroller-based fault detection having a backup circuit for causing the circuit breaker to trip in response to a microcontroller fault, including a timing circuit powered by a power supply and a microcontroller. The timing circuit is electrically coupled to an SCR that causes the circuit breaker to trip. The timing circuit includes a BJT coupled to the gate of the SCR. The microcontroller has a first output coupled to the timing circuit and a second output coupled to the SCR. The first output is coupled to a node between a resistor and a grounded capacitor in the timing circuit, and the node is coupled to a gate of the SCR and to a base of the transistor. A voltage develops at the node sufficient to cause the gate of the SCR to turn on unless the microcontroller pulls the first high-impedance output to a logic low state.