Low-Voltage Circuit Breaker Arc-Pressure Trip for Fast Opening
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Solution Overview
Problem
Current low-voltage power circuit breakers with quick acting trip devices face issues such as undesired tripping in the absence of arcing phenomena, complex calibration due to non-linear mechanisms, reliability concerns due to spring aging, and increased manufacturing costs from numerous complex parts.
Innovation Solution
A low-voltage circuit breaker with a quick acting trip device that reacts directly and linearly to arc development, featuring a plunger and trip lever mechanism where the intervention threshold is fixed during design, allowing independent pole operation and reducing calibration needs, and is designed to be reliable and cost-effective.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If traditional opening springs are used to open contacts, then the circuit breaker can provide basic protection, but the intervention time is too long and the breaking capacity is insufficient for high short-circuit currents
Solution Approach 1:
The patent converts the harmful electrodynamic repulsion forces generated during short-circuit conditions into a beneficial thrust that accelerates contact separation. The repulsion forces between fixed and movable contacts, which would normally be detrimental, are harnessed to increase the separation speed and improve breaking capacity without requiring additional active components.
Solution Approach 2:
The patent introduces a magnetic circuit as an intermediary mechanism that mediates between the electrical fault condition and the mechanical tripping action. The magnetic circuit converts electrical energy into mechanical motion through electromagnetic interaction, providing a reliable and fast tripping mechanism that overcomes the limitations of pure spring-based systems.
2Loss of time
If magnetic circuits with concatenated electrical circuits are used for quick tripping, then the intervention time is reduced, but undesired tripping occurs in the absence of arcing phenomena and calibration becomes complex
Solution Approach 1:
The patent applies local quality by positioning the magnetic circuit specifically in the arc chamber where arcing phenomena occur. The quick-acting tripping mechanism is triggered only when arc development is detected in this localized region, ensuring that tripping occurs only under genuine fault conditions and preventing false tripping from unrelated electrical disturbances.
Solution Approach 2:
The patent uses arc development (visual/physical change in the arc chamber) as the trigger signal for tripping. The appearance and intensity of the electric arc serve as the indicator that triggers the magnetic circuit, providing a reliable and simple detection mechanism that avoids complex calibration while ensuring tripping only occurs during actual arcing events.
3Device complexity
If spring-based actuation mechanisms are used, then the device structure is simpler, but the reliability decreases due to spring aging over time
Solution Approach 1:
The patent replaces the mechanical spring-based actuation system with an electromagnetic actuation system. The magnetic circuit eliminates the need for storing mechanical energy in springs, thereby removing the aging-related reliability issues associated with spring degradation while maintaining a relatively simple device structure through the use of standard electromagnetic components.
4Reliability
If complex kinematic mechanisms with multiple parts are used for opening contacts, then the breaking capacity can be increased, but the manufacturing cost increases and the device becomes more complex
Solution Approach 1:
The patent merges the tripping function and the contact opening function into a single integrated mechanism. The magnetic circuit directly drives the contact supporting shaft to rotate and open the contacts, eliminating the need for separate complex kinematic mechanisms while maintaining high breaking capacity. This integration reduces the number of parts and simplifies the overall device structure.
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 provides a reliable and efficient tripping mechanism that is independent for each pole, unaffected by aging, and simplifies calibration, resulting in a more prompt and economical circuit breaker design.
Implementation Method 1
arc development in a arc chamber (40) between a first fixed contact (20) and a first moving contact (21)
Implementation Method 2
plunger (101) inserted in a first channel (102) connected to an arc chamber (40) of the corresponding pole, said plunger having a first operative surface (103) subjected to the pressure of said arc chamber
Data Source
Figure 1
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AI summary
A low-voltage circuit breaker, comprising: at least one fixed contact, for each pole, which is electrically connected to a terminal for connection to an electric circuit and a corresponding moving contact which is associable/separable with respect to said fixed contact by means of a rotation of said moving contact; an arc chamber positioned in correspondence of said fixed contact; a rotating contact supporting shaft common to all poles, which is functionally connected to an actuation mechanism of the circuit breaker, said actuation mechanism comprising a kinematic system operatively connected to an actuation lever for opening/closing operations and provided with opening springs and a tripping shaft for releasing said kinematic system and allowing its movement from a closed to an open position. The low-voltage circuit breaker is characterized in that it comprises for each pole a quick acting trip device comprising a plunger inserted in a first channel connected to an arc chamber of the corresponding pole, said plunger having a first operative surface subjected to the pressure of said arc chamber and a second operative surface, said quick acting trip device further comprises a trip lever having a first portion cooperating with said tripping shaft and a second portion cooperating with the second operative surface of said plunger.