Dual-Contact Relay Decoupling for Welded Contact Safety
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Solution Overview
Problem
Double contactors in high-powered circuits face safety issues due to the likelihood of one contact becoming welded during switching, leading to unintended permanent connection and impaired safety, as both contacts remain closed even when the control circuit is switched off.
Innovation Solution
A relay design with electrically isolated switching contacts and an actuator that moves movable contacts between conductive and isolated states, allowing for independent operation of each contact to prevent welding-induced failures, using a drive element that can transition between positions based on coil state, and incorporating mechanical arrangements like arms and joints to facilitate movement and decoupling in case of faults.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If both movable contacts are connected in a mechanically rigid manner to close and open switching contacts simultaneously, then the switching operation is simplified and coordinated, but the safety is impaired because if one contact becomes welded, both contacts remain closed even when the control circuit is switched off
Solution Approach 1:
The patent divides the mechanically rigid connection into two independent movable contacts (first movable contact and second movable contact) that are no longer mechanically coupled. Each contact can now operate independently, allowing one contact to open even if the other becomes welded, thereby resolving the safety issue while maintaining coordinated switching through separate actuation paths
2Productivity
If switching sparks occur during the switching procedure, then the switching contacts can be actuated, but the contacts may become so hot that they become welded, leading to unintended permanent connections
Solution Approach 1:
By segmenting the single switching mechanism into two independent switching contacts with separate movable contacts, the patent ensures that welding of one contact does not prevent the other from opening. This segmentation isolates the harmful effect of welding to only one contact path, maintaining overall system reliability
Solution Approach 2:
The patent inverts the traditional approach by allowing the movable contacts to be actuated independently rather than being rigidly coupled. This inversion enables the system to tolerate welding in one contact while the other contact can still be opened by the actuator, reversing the failure mode from 'both contacts stuck' to 'at least one contact can open'
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
Ensures simultaneous disconnection of load circuits for both switching contacts, maintaining safety by allowing the non-welded contact to open even if the other becomes welded, thus preventing unintended permanent connections and ensuring reliable operation.
Implementation Method 1
The actuator may be configured with a coil, switchable from an idle state into a state in which current is flowing, wherein the position of the drive element depends upon the state of the coil
Data Source
AI summary
A relay is disclosed. In an embodiment a relay includes a first switching contact having a first main contact, a second main contact and a first movable contact; a second switching contact having a third main contact, a fourth main contact and a second movable contact, wherein the second switching contact is electrically isolated from the first switching contact; and an actuator configured to move both the first and second movable contacts from a first switching state into a second switching state by moving a drive element of the actuator from a first position into a second position.