Removable Disconnect Link for Safe Terminal Circuit Isolation
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Solution Overview
Problem
Existing industrial terminal connectors, particularly screw-less type terminals, lack a safe and reliable method to disconnect circuits for maintenance, risking accidental reconnection and exposure to voltage due to the use of circular pins that can be mistaken for test sockets.
Innovation Solution
A terminal unit with a removable link featuring a flat 'U' shaped conductor and a distinctively colored shroud and handle, which prevents accidental connection by using a flat staple and folded contacts, ensuring the link can only be inserted correctly and providing visual and tactile feedback for safe operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a circular pin is used as the connection link, then the link can be easily inserted and removed, but it exposes the hole which is the same size as 4mm test points, creating a safety hazard where test leads could be mistakenly inserted
Solution Approach 1:
The link opening is designed with an asymmetric shape (e.g., D-shaped or with a specific profile) that differs from the circular test sockets. The link itself has a corresponding asymmetric shape with a protrusion or flat edge that only fits in one orientation. This asymmetry prevents mistaken insertion of circular test leads into the link opening while maintaining easy operation of the correct link.
Solution Approach 2:
The link opening has a specific local geometric feature (such as a flat edge, protrusion, or non-circular contour) that is different from the uniform circular shape of test sockets. This local quality difference creates a mechanical key-lock system where only the correct link can be inserted, eliminating the safety hazard while preserving ease of operation.
2Ease of repair
If the link is removed for circuit disconnection, then maintenance can be performed, but the circuit is prone to reconnection without warning if someone replaces the link
Solution Approach 1:
The link incorporates a dynamic visual indication system that changes state based on its insertion status. When the link is inserted in the correct orientation, a visual indicator (such as a colored window, flag, or positioned component) displays a safe state. When removed or incorrectly inserted, the indicator displays a warning state, providing continuous feedback on circuit status and preventing accidental reconnection.
Solution Approach 2:
The link assembly includes a feedback mechanism that provides visual information about the circuit's connection status. This feedback system allows technicians to immediately know whether the circuit is connected or disconnected, and whether the link is properly installed, thereby preventing accidental reconnection during maintenance and ensuring safety.
3Reliability
If a flat 'U' shaped conductor with folded contacts is used, then accidental connection is prevented, but the link cannot be inserted in reverse orientation which provides visual and tactile feedback
Solution Approach 1:
The link features an asymmetric flat 'U' shaped conductor with folded contacts that can only engage with the terminal openings in one specific orientation. The geometric asymmetry ensures that the link cannot be inserted backwards, providing both mechanical prevention of incorrect connection and tactile feedback to the operator during insertion.
Solution Approach 2:
The link incorporates color-coded elements such as a colored shroud, painted surfaces, or colored indicators that change appearance or become visible based on the link's orientation. When the link is correctly inserted, the color indicates a safe connected state. If attempted in reverse, the color pattern or visibility changes to indicate incorrect orientation, providing visual feedback that complements the mechanical asymmetry.
Data Source
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AI summary
A terminal unit has a terminal unit body, a first terminal connector located adjacent a first opening in the terminal unit body for connection of a first conductor passing through the first opening, and a second terminal connector located adjacent a second opening in the terminal unit body for connection of a second conductor passing through the second opening. The first terminal connector conductor terminates internally of the terminal unit at a first link connection point, and the second terminal connector conductor terminates internally of the terminal unit at a second link connection point. The first and second link connection points are accessible via a link opening in the terminal unit body and a removable link comprising a link conductor and a link handle is removably insertable into the link opening. With the removable link inserted a normal orientation, the link conductor electrically connects the first link connection point and the second link connection point to electrically connect the first terminal connector to the second terminal connector.