Movable Earth Collector for Cable Dielectric Testing Safety
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Solution Overview
Problem
During cable dielectric tests in medium voltage cells, there is a risk of losing the earth function when installing or removing clamps, leading to safety concerns and potential insulation faults due to incorrect reconnection or forgotten earthing.
Innovation Solution
A cable dielectric test device with a movable earth collector that can be rotated between connected and disconnected positions, featuring interlocking mechanisms to ensure safe operation and prevent accidental disconnection or reconnection, along with contact pressure springs for reliable current evacuation during short-circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the earth collector is removed during cable testing, then voltage injection can be performed, but the risk of losing earth connection and causing safety hazards increases
Solution Approach 1:
The earth collector is designed as a movable component that can dynamically change position between connected and disconnected states. It rotates about a pivot axis to move between a closed position (connecting cables to earth) and an open position (remote from cable connection inserts), enabling both safety and testing functionality
Solution Approach 2:
The movable earth collector acts as an intermediary between the cable connection inserts and the earth connection. It provides a controlled transition state, allowing the system to move safely between earthed and non-earthed conditions during testing operations
2Reliability
If the earth collector is kept connected during testing, then safety is maintained, but voltage injection for testing cannot be performed
Solution Approach 1:
The earth collector's movable design allows it to switch between connected and disconnected states as needed. During normal operation it maintains earth connection for safety, and during testing it rotates to the open position to enable voltage injection
3Ease of operation
If manual reconnection of earth collector is required after testing, then flexibility is maintained, but the risk of incorrect reconnection or forgotten earthing increases
Solution Approach 1:
The interlocking mechanism provides feedback control by detecting whether the earth collector is properly connected before allowing equipment operation. The lock prevents withdrawal during testing, and another lock prevents reconnection until testing is complete, ensuring correct procedural sequence
Solution Approach 2:
The system performs self-checking through the interlocking mechanism, automatically preventing unsafe operations without requiring external verification. The locks and keys ensure the earth collector is properly positioned before allowing equipment to be energized or tested
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 device ensures improved safety and reliability during cable testing by maintaining the earth connection throughout the test process, preventing accidental disconnection and ensuring correct reconnection, thus enhancing the accuracy and safety of cable insulation fault detection.
Implementation Method 1
contact pressure springs ensure the contact pressure between the collectors and the studs
Data Source
Figure 1
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AI summary
The device (D) has studs (15-17) mounted in a support (33) and respectively and electrically connected to cables. The studs are arranged to be electrically connected to an earth bar (27) to connect the cables to an earth before installation of injection fingers (12) on inserts of the cables. The bar is mounted in the support between a closed position in which the bar connects the studs to allow installation of the fingers, and an open position in which the bar is removed from the studs to allow injection of voltage into the cables.