Generator End-Winding Vibration Analysis - A Capstone Experience

The end-windings of large generators are exposed to some of the largest vibrations among all machines. The stability of these end windings has a major impact on the reliability of generators. A resonant vibration condition can lead to movement and forces that can compromise the stator bar insulation and possibly cause a complete failure of the generator. Currently, there is not a set of established industry standards or acceptance criterion for generator end winding vibration. There are many differing points of view within the power industry concerning the sources of vibration, methods of analysis, and solutions. This applied research paper investigates generator end winding vibration in order to establish a foundation to further the discussion among industry and academia in seeking to form a set of standards. This project relates directly to the problem of synchronous generator end-winding vibration at the J.H. Campbell power generating facility located in West Olive, Michigan. There were significant concerns that the end-windings for the A and B generators at the Unit-1 power plant were experiencing excessive levels of end-winding vibration and were at risk of a major failure. The objective of this capstone project was to perform an overall assessment including a determination of the cause of vibration, vibration testing, data acquisition, and analysis of the end-windings for each machine. It was concluded that the resonant vibration at a frequency equal to the fundamental electrical frequency as well as harmonic components of the fundamental frequency is the root cause of the end-winding vibration for each synchronous generator. Based on the analysis of test data a long term solution was established and executed successfully to reduce the vibration problem. This is an industryuniversity collaboration that is very important to enhance engineering education and research.