Thermal Trip Calibration Locking for Electrical Protection Devices
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing thermal trip units in electrical protection devices, such as circuit breakers, are difficult to calibrate accurately and securely, leading to high discard rates and increased costs due to unsatisfactory initial calibration attempts.
Innovation Solution
A thermal trip unit with a bimetallic strip that is elastically deformable during calibration, allowing for repeat adjustments and a locking mechanism to secure the position after calibration, ensuring precise and reversible calibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a calibration screw is used to plastically deform the bimetallic strip support, then the calibration becomes secure and prevents malfunction during operation, but recalibration is prevented if the first calibration attempt is unsatisfactory, leading to high discard rates
Solution Approach 1:
The invention changes the calibration mechanism from plastic deformation to elastic deformation. The adjustment element can be actuated to move the attachment portion and adjust the bimetallic strip position elastically during calibration. After calibration, a locking element secures the adjustment element in its adjusted position, maintaining the calibration securely while allowing recalibration if needed.
Solution Approach 2:
The invention introduces a dynamic calibration system where the adjustment element can be moved during calibration and then locked in position. The locking element transitions from an unlocked state (allowing adjustment) to a locked state (securing calibration), providing both adjustability and security without requiring plastic deformation.
2Productivity
If a large safety margin is chosen during calibration, then the discard rate is reduced, but calibration accuracy is compromised
Solution Approach 1:
The dynamic adjustment and locking system allows for precise calibration without needing large safety margins. The adjustment element can be finely tuned to achieve accurate calibration, and the locking element secures this precise position, eliminating the need to compromise accuracy with excessive safety margins.
3Adaptability or versatility
If the adjustment element is made accessible after calibration, then future adjustments are possible, but the device may malfunction during operation due to unintended movement
Solution Approach 1:
The locking element provides a dynamic state change: during calibration, the adjustment element is accessible and can be moved; after calibration, the locking element secures the adjustment element in its adjusted position, preventing unintended movement while maintaining the option for future recalibration by unlocking and re-adjusting.
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 easy, precise, and reversible calibration of thermal trip units, reducing discard rates and associated costs while preventing malfunction during operation.
Implementation Method 1
This strip heats up due to the Joule effect and deforms, thus opening the electrical circuit.
Implementation Method 2
a bimetallic strip, which has a separate attachment end and an actuating end, the bimetallic strip being deformable, when heated, between a rest configuration and a deformed configuration
Implementation Method 3
the thermal trigger is configured, when the adjustment member is actuated, to deform the support elastically
Data Source
Figure 1
Figure 2
Figure 3
AI summary
This electrical protection device (12) includes a housing (30), at least one conduction path with a movable contact (76) actuated by a switching mechanism (150), and a thermal release (112), which includes a bimetallic strip (113), mounted on a support (284) connected to the housing and configured to tilt the switching mechanism (150) into an open configuration, and an adjusting member (300), actuable through an outer wall (305) of the housing and configured to elastically deform the support (284) so as to adjust the position of the bimetallic strip relative to the switching mechanism.For more precise adjustment of the thermal trigger, the adjusting member (300) is configured to elastically deform the support (284), while the thermal trigger also includes a locking device (316), which selectively has an engaged configuration, in which the locking device (316) blocks the adjusting member, and a released configuration, in which the adjusting member is not blocked.