Retightenable Wedge System for Generator Stator Coil
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Solution Overview
Problem
The existing wedge systems in generator stators tend to loosen over time, leading to coil movement within the slots, which can damage the stator and requires costly and time-consuming periodic re-wedging processes, involving the removal of the rotor for tightening.
Innovation Solution
A retightenable wedge system comprising a first filler layer, a spring member, and a retightenable wedge assembly with a tightening member and locking member, where the tightening member is configured to apply a radial load through a form fit feature in the aperture of the slot wedge, and the locking member engages to prevent backing out, allowing for easy re-tightening without rotor removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional wedge system is used to tighten the coil in the slot, then the coil is initially secured in place, but the wedge system becomes loose over time requiring periodic re-wedging that involves rotor removal
Solution Approach 1:
The wedge system incorporates a dynamic retightening mechanism that allows the wedge to be adjusted and re-tightened in place without removing the rotor. The system transitions from a static, permanent installation to a dynamic, adjustable configuration that can be maintained during operation.
Solution Approach 2:
The wedge assembly is divided into separable components including the wedge itself, retaining structures, and adjustment mechanisms. This segmentation allows individual parts to be accessed and adjusted independently without requiring complete disassembly of the generator.
2Reliability
If periodic re-wedging is performed to maintain wedge tightness, then coil movement is prevented, but the process is time and material consumptive requiring rotor removal
Solution Approach 1:
The wedge system incorporates self-retightening capabilities through spring-loaded mechanisms and elastic deformation features that automatically maintain tightness without requiring external intervention or rotor removal for routine maintenance.
Solution Approach 2:
The wedge assembly is pre-configured with adjustment mechanisms and retaining structures during manufacturing that enable future retightening operations without requiring complex disassembly procedures or rotor removal.
3Ease of operation
If the wedge system is made adjustable for retightening, then maintenance becomes easier, but the device complexity increases
Solution Approach 1:
The retightening adjustment mechanisms are localized to specific regions of the wedge assembly where they are most needed, rather than distributing complexity throughout the entire structure. This concentrates the added complexity only where functional benefits are achieved.
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 system effectively maintains the coil in place, reducing stator damage and eliminating the need for repetitive axial driving of wedges, enabling efficient and cost-effective maintenance by allowing radial tightening from the top, thus reducing manpower and material costs.
Implementation Method 1
a spring member placed on the first filler layer... configured to apply the evenly distributed radial load onto the coil for tightening the coil in the slot
Data Source
AI summary
A retightenable wedge system for tightening a coil in a slot of a generator stator bar is presented. The retightenable wedge system includes a first filler layer, a spring member, a second filler layer and a retightenable wedge assembly. The retightenable wedge assembly includes a slot wedge having an aperture, a tightening member having form fit feature and a locking member having mating form fit feature. The tightening member is tightenable in the aperture such that a radial load is applied on the second filler layer for tightening the coil in the slot. The tightening member is locked in place in the aperture by an engagement between the form fit feature of the tightening member and the mating form fit feature of the locking member such that the tightening member is restrained from backing out of the slot wedge.