Miniature Circuit Breaker Electronic Trip Mechanism
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional miniature circuit breakers (MCBs) have variable and potentially long disconnect times for short circuit conditions due to reliance on solenoids and bimetal components, which are not capable of detecting current and determining overcurrent conditions based on sensor outputs, leading to inconsistent and potentially lengthy interruption times.
Innovation Solution
Incorporating a current sensor and control unit that detects overcurrent conditions and generates a trip signal to trigger the contact opening mechanism independently, allowing for a shorter and more consistent disconnect time, and using an electric motor to assist in contact opening and closing, reducing wear and improving response times.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a solenoid and bimetal component are used in the trip mechanism, then the MCB can detect overcurrent conditions and trigger contact opening, but the disconnect time becomes variable and potentially long
Solution Approach 1:
The patent replaces the conventional solenoid-based mechanical trip mechanism with an electronic control system. A current sensor detects the overcurrent condition and sends a signal to a control unit, which then actuates an electromechanical actuator to open the contacts. This substitution of mechanical detection (solenoid) with electronic detection (sensor + control unit) enables faster and more consistent response times, directly resolving the contradiction between reliability of overcurrent protection and disconnect time variability.
2Device complexity
If a conventional solenoid-based trip mechanism is used, then the MCB structure is simple, but the response time is inconsistent and potentially lengthy
Solution Approach 1:
The patent replaces the purely mechanical solenoid-based trip mechanism with an electronic control system comprising a current sensor, control unit, and electromechanical actuator. The sensor electronically detects overcurrent conditions and the control unit processes the signal to trigger contact opening, replacing mechanical detection and timing with electronic processes that are faster and more consistent, thereby improving response speed while accepting increased device complexity.
3Device complexity
If a manually operable lever is used to close contacts, then the MCB structure is simple, but automatic operation is not possible
Solution Approach 1:
The patent employs an electromechanical actuator that serves multiple functions: it can close the contacts under automatic control when an overcurrent condition is detected, and it can also close the contacts manually when operated by a user. This multi-functional actuator replaces the simple manual lever while enabling automatic operation, resolving the contradiction between device complexity and extent of automation.
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 enables faster and more consistent disconnection during short circuit conditions, reducing energy let-through and preventing contact welding, while also allowing for adjustable threshold settings and automatic contact operation, enhancing the reliability and efficiency of the MCB.
Implementation Method 1
a sensor to detect current through the main current path
Implementation Method 2
the coil generates a magnetic field which acts on the armature with a force
Implementation Method 3
If an overcurrent flows through the main current path then the bimetal begins to heat up
Implementation Method 4
Continued heating due to a prolonged overcurrent causes the bimetal to deform
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A miniature circuit breaker (1) having a control unit (22) arranged to produce a trip signal to trigger a trip mechanism (20) into opening a pair of contacts (8,10) if it determines that an overcurrent condition occurs based on an output of a current sensor (23); an electric motor (25) operable to close the contacts via a contact closing mechanism (30a); a force transfer mechanism (70) arranged to transform a first trigger force into a second trigger force larger than the first trigger force, wherein the force transfer mechanism couples an electromechanical actuator (61) to a contact opening mechanism (30b) such that the second trigger force triggers the contact opening mechanism into opening the contacts; and/or a mechanical energy store (44, 46) arranged to accumulate mechanical energy from operation of the closing actuator (25) and subsequently to release accumulated mechanical energy to close the contacts.