Fail-Safe Electronic Circuit Breaker with Relay Intermediary
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Solution Overview
Problem
Existing electronically controlled circuit breakers relying solely on solid-state microprocessor electronics for protection lack fail-safe mechanisms, potentially leaving them in an 'on' state during overloads, posing safety risks and incurring high costs and heat dissipation issues, without the redundancy of traditional electro-mechanical designs.
Innovation Solution
An electronically programmable AC circuit breaker incorporating a relay circuit, either electro-mechanical or solid-state, with a magnetic coil solenoid device and an electronic control circuit programmed for trip parameters, including overload and inrush current protection, ensuring the breaker trips if electronic monitoring fails, and incorporating a normally closed relay to maintain a fail-safe state.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If solid-state microprocessor controlled electronics are used to provide protection against current overload and inrush current, then precise protection control and programming capability are improved, but reliability deteriorates because the breaker may remain in an 'on' state during overload if the electronic circuitry fails
Solution Approach 1:
A relay circuit is introduced as an intermediary component between the electronic control system and the trip mechanism. The relay acts as a mediator that can be controlled by the electronic system but also independently triggers the trip function through its coil, ensuring that electronic failure does not prevent breaker operation. The relay's normally closed contacts provide a fail-safe path that bypasses electronic control when needed.
Solution Approach 2:
The protection system is segmented into distinct functional components: electronic monitoring circuitry for precise measurement and control, a relay circuit for intermediate control and fail-safe functionality, and a mechanical trip mechanism for final execution. This segmentation allows each component to perform its specialized function while providing redundancy through the relay's independent trip capability.
2Reliability
If traditional electro-mechanical means are used to provide protection against current overload and inrush current, then reliability is improved through inherent failure-proof construction, but measurement precision and programmable protection capability deteriorate
Solution Approach 1:
The patent merges the advantages of electronic control systems (precise measurement, programmable parameters, ground-fault and arc-fault detection) with the reliability of traditional electro-mechanical trip mechanisms. The electronic system handles monitoring and control functions with high precision, while the mechanical relay and trip mechanism provide inherent reliability and fail-safe operation.
3Device complexity
If solely solid-state electronics are used for switching high voltage AC power, then device complexity is reduced, but heat dissipation problems and cost increase
Solution Approach 1:
The patent replaces solid-state electronic switching components with a mechanical relay system for high voltage AC power switching. The relay's mechanical contacts physically open and close the circuit, eliminating the heat dissipation issues associated with solid-state switches handling high voltages. This mechanical approach reduces energy loss while maintaining acceptable device complexity.
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 ensures the circuit breaker remains fail-safe by tripping in case of electronic failure, providing precise protection against overloads and faults while minimizing heat dissipation and cost, and is applicable for both AC and DC circuits, ensuring safety and efficiency.
Implementation Method 1
The breaker employs a simple, inexpensive, magnetic coil solenoid device to activate the breaker's trip function
Implementation Method 2
The circuit breaker also includes a normally closed relay having a relay activating circuit and a switching circuit
Data Source
AI summary
A circuit breaker includes main contacts movable between closed and open positions such that a line terminal and a load terminal are, respectively, in electrical communication or electrically isolated. A trip coil is connected to the contacts, causing the contacts to move from the closed position to the open position in response to a trip current, thereby tripping the circuit breaker. A normally closed relay having a relay activating circuit and a switching circuit is provided, with the switching circuit being electrically connected to the trip coil. A monitoring circuit is electrically connected to the relay activating circuit, supplying activating power to the relay activating circuit so long as a determination is made that the breaker is operating within acceptable parameters, and ceasing to supply activating power to the relay activating circuit upon a determination being made that the breaker is not operating within acceptable parameters, thereby tripping the breaker.