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Abstract
When the rotor of the hydroelectric generator is running, the centrifugal force of the rotor rim is very high. Centrifugal force will produce obvious radial deformation on the rotor rim lamination, which will cause a radial separation gap between the rim and the rotor spider. The larger the diameter of the rotor, the larger the separation gap, therefore, when the rotor is assembled, each component is required to have sufficient strength, good balance and integrity. In order to ensure the stability and balance of the rim during the installation, it is necessary to focus on the technical measures to control installation of the wedges, to complete the thermal keying operations in strict accordance with the requirements. The purpose of the rotor thermal keying is to maintain the safety and stability during operation, to facilitate rim and rotor hub to be closely combined, and to achieve a reliable cooperation between them. A certain amount of mechanical compression is applied simultaneously between rim and rotor spider, which can generally be achieved by thermal keying or conventional rim hot keying on the basis of cold keying, the rim is heated to generate gap between rotor rim and hub, the keys are driven to the gap in specified depth. After the rotor rim is cooled down, the effective coordination between rotor rim and rotor hub can be ensured, the centripetal force generated during the operation of the unit can be offset to maintain the unit’s reliable operation. The installation of hydro-generator rotor’s wedge is an important process, it's a matter of the roundness and concentricity, higher requirements is needed for large capacity generators. Based on the structural characteristics of the rotor installed at the Ludila Power Station on the Jinsha River, this article introduces the installation and welding process of the wedges for the rotor at the Ludila Power Station, as well as the difference between thermal keying technology and conventional rim hot keying. Quality control, installing procedure and methods for installation of rotor wedge are described. This article could provide guidance and reference for the implementation of similar projects, research on new advanced technology for the industry.
Highlights
When the rotor of the hydroelectric generator is running, the centrifugal force of the rotor rim is very high
With more large-capacity units been applied in projects, to ensure that the rim and the rotor hub will not produce a separation gap when the unit is operating at the separation speed of the unit, measures against gap have been applied during the assembly of the rotor, especially the installation of Rotor wedge and the thermal keying for rotor rim [2,3,4,5,6]
Thermal keying is based on cold keying, on heating, rim expands to generate the gap between the rim and the rotor hub
Summary
When the rotor of the hydroelectric generator is running, the centrifugal force of the rotor rim is very high. For large-scale units, the huge centrifugal force will cause obvious radial deformation on the rim lamination, which will cause a radial separation gap between the rim and the rotor support [1]. With more large-capacity units been applied in projects, to ensure that the rim and the rotor hub will not produce a separation gap when the unit is operating at the separation speed of the unit, measures against gap have been applied during the assembly of the rotor, especially the installation of Rotor wedge and the thermal keying for rotor rim [2,3,4,5,6]. Traditional thermal keying is generally used for small-capacity, low-speed operating units, which could cause uneven force. To eliminate uneven force, most large-scale hydro-generator rotor assembly adopts hot padding method. In view of the rotor structure at Ludila power station, wedge structure and thermal keying are connected and fixed with the rim for installation
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