Circuit Breaker Trip Apparatus Reducing Sensor Force
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Solution Overview
Problem
Circuit breakers require high forces for tripping mechanisms, which can be challenging for sensors to activate, especially in designs that couple the trip device directly with the operating mechanism, and auxiliary trip systems face difficulties in harvesting and converting residual energy into sufficient mechanical force efficiently.
Innovation Solution
A trip apparatus that decouples the sensor from the operating mechanism using a microswitch and controller, where the sensor changes the switch's state to activate an actuator, reducing the force required for tripping and allowing for easier energy utilization in auxiliary trip systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a trip device is directly coupled with the operating mechanism, then the trip function is simple and reliable, but the force required by the sensor is very high (up to 4 N or more)
Solution Approach 1:
A secondary latching system with a trip bar is introduced as an intermediary between the trip device and the operating mechanism. The trip device acts on the trip bar, which then triggers the latching system to release the operating mechanism. This mediator reduces the force requirement from 4 N to approximately 2.5 N while maintaining reliable trip function.
Solution Approach 2:
The trip apparatus is segmented into distinct functional components: the trip device (sensor), the trip bar, the secondary latching system, and the operating mechanism. This segmentation allows each component to be optimized independently, with the trip bar and latching system working together to reduce the force burden on the sensor while ensuring reliable mechanism activation.
2Force
If a secondary latching system is used to reduce trip force, then the force required by the trip device is reduced (from 4 N to 2.5 N), but the device complexity increases significantly
Solution Approach 1:
The trip bar serves multiple functions: it acts as a mechanical linkage between the trip device and latching system, provides a common interface for both electromagnetic and thermal trip devices, and enables the force-reduction mechanism. This multi-functionality reduces overall system complexity despite the addition of the latching system.
Solution Approach 2:
The system changes the force parameter distribution by introducing springs in the latching system that store mechanical energy. The trip device only needs to overcome a small portion of the total trip force (2.5 N), while the spring energy provides the majority of the force needed to activate the operating mechanism, thereby reducing the sensor force requirement.
3Speed
If auxiliary trip systems harvest residual energy to create mechanical force, then rapid tripping is achieved, but the energy conversion efficiency is low and design is difficult
Solution Approach 1:
The patent replaces complex mechanical energy harvesting and conversion systems with a simpler approach using pre-charged springs in the latching system. The springs are charged during normal operation and automatically release stored energy when triggered, eliminating the need for complex real-time energy conversion mechanisms while achieving rapid tripping.
Solution Approach 2:
Energy is stored in the latching system springs during normal breaker operation (preliminary action), rather than converting residual energy at the moment of tripping. This preliminary energy storage simplifies the auxiliary trip system design and improves energy conversion efficiency by using readily available spring energy when a trip condition occurs.
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
This solution reduces the force needed for sensors to trip the breaker, enabling smaller and more cost-effective designs while allowing for more efficient and tunable auxiliary trip systems that can operate with less energy.
Implementation Method 1
An example of an electromagnetic trip device is a solenoid serially connected to a line conductor of the breaker and arranged to activate the operating mechanism when current in the line conductor exceeds a predetermined level.
Implementation Method 2
An example of a thermal trip device is a thermal element, typically a bimetallic element (bimetal), serially connected to a line conductor of the breaker and arranged to activate the operating mechanism when current in the line conductor has exceeded a predetermined level for a predetermined amount of time.
Data Source
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AI summary
A circuit interrupter trip apparatus operably connected to an operating mechanism of a circuit interrupter includes a sensor and a switch operably connected and responsive to the sensor. The switch is positioned such that the sensor changes the operating state of the switch in response to detection of a predetermined electrical condition, such as an electrical fault. A controller is operably connected to the switch and is configured to activate the operating mechanism in response to a change in the operating state of the switch.