Study on Analysis of Causes for Loosening in the Ring Leads Fixed Structure at the Generator End and Improvement Measures

Abstract

In response to the repeated occurrence of loosening in the fixed structure of the ring leads at the end of generator, as well as issues such as bolt loosening and lead wear, during the recent major overhauls of a large steam turbine generator, this paper conducts an analysis of the causes of loosening and proposes corresponding improvement measures. Taking the generator end ring leads fixed structure as the research object, this paper employs comparative analysis and finite element simulation methods to analyze the causes of loosening. It identifies factors such as bolt fixing methods and cleat support methods contributing to loosening, and proposes improvement solutions including increasing the wrapping angle of the cleat and enhancing pretightening force of the bolts. According to the actual component size of the unit, a sample test platform is designed and built, and the correctness of the loosening cause and the effectiveness of the improvement plan are verified by the sample test. The experimental results confirm that the cleat support form and bolt fixing method significantly contribute to fixing structural loosening, while the proposed improvements effectively delay bolt loosening. Increasing the cleat wrapping angle and pre-tightening force of the bolts are both feasible on-site and offer practical engineering value, laying the foundation for solving the technical challenges associated with securing the generator’s end ring lead structure and ensuring safe and stable generator operation.

Keywords

• Large generators
• electromagnetic exciting force
• vibration control
• analysis of loosening causes
• structural improvement scheme