Outer End Ring Repair for Cracked Motor Rotor Conductive Rings
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Solution Overview
Problem
The repair of cracked conductive end rings and welds in heavy-duty AC induction motors is labor-intensive and costly, requiring grinding and replacement, which disrupts motor operation and increases downtime.
Innovation Solution
A method involving the attachment of an outer end ring that provides an uninterrupted electrically conductive path over cracks in the conductive end rings, eliminating the need for grinding and replacement, and using weld beads to secure the outer end ring to the conductive end rings and electrical conductors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If grinding and cutting away of damaged conductive end rings and weld metal is performed, then structural integrity is restored, but labor cost and repair time increase significantly
Solution Approach 1:
The end ring system is segmented into two functional parts: the original conductive end ring (which may be cracked) and the new outer end ring (which provides the conductive path). The outer end ring is a separate component that can be added without removing the damaged inner ring, thus avoiding time-consuming grinding and cutting operations while restoring structural and electrical integrity.
Solution Approach 2:
The outer end ring acts as an intermediary component that bridges the cracks in the damaged conductive end ring. It provides an alternative conductive path around the damaged areas, allowing the system to function without removing the original damaged components, thereby reducing repair time and labor costs.
2Reliability
If grinding and cutting away of damaged conductive end rings is performed, then cracks are removed, but labor cost increases
Solution Approach 1:
The solution segments the end ring functionality between the original damaged ring and the new outer ring. The outer ring is a pre-fabricated component designed to provide electrical connectivity without requiring removal of the damaged inner ring, thus eliminating labor-intensive grinding and cutting operations while ensuring reliable electrical connections.
Solution Approach 2:
The outer end ring is a relatively simple, cost-effective component that can be added to restore functionality. Rather than performing expensive and time-consuming grinding and welding operations to remove and replace entire end rings, the invention uses a simpler outer ring that provides the necessary electrical connectivity at lower cost.
3Reliability
If replacement of conductive end rings is performed, then structural integrity is improved, but the rotor is out of service for extended periods
Solution Approach 1:
The end ring system is divided into the original conductive end ring and the additional outer end ring. This segmentation allows the outer ring to be installed without removing the damaged inner ring, enabling faster repair and reducing motor downtime while maintaining overall structural integrity through the combined ring system.
Solution Approach 2:
The outer end ring is designed as a pre-fabricated component that can be directly installed over the damaged conductive end ring. This preliminary preparation of the outer ring allows for quick installation without requiring time-consuming on-site grinding, cutting, or complete disassembly operations, thus improving motor availability during repair.
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
This method significantly reduces repair time and costs by maintaining electrical connectivity and structural integrity without removing the conductive end rings, ensuring minimal downtime and maintaining motor performance.
Implementation Method 1
The outer end ring is attached to the conductive end ring and the electrical conductors by weld metal
Implementation Method 2
an outer end ring abutting and electrically connected to one of the pair of conductive end rings and electrically connected to adjacent ends of the plurality of electrical conductors
Data Source
AI summary
A repaired rotor of a multi-phase electric motor includes a plurality of annular laminations stacked to form a cylindrical core about a central axis, each of the laminations having notches aligned to form axially extending slots about a periphery of the core; a plurality of electrical conductors extending through the slots; a pair of conductive end rings, each attached to a different end of the cylindrical core and electrically connected to the plurality of electrical conductors; and an outer end ring abutting and electrically connected to one of the pair of conductive end rings and electrically connected to adjacent ends of the plurality of electrical conductors, the outer end ring providing an uninterrupted electrically conductive path connecting the plurality of electrical conductors.