Trending of EMI data over years and overnight

Trending data is a time proven technique to better analyze conditions, verify repairs, identify stable conditions or detect deterioration that may be developing. Often this comparison of data takes place over a long period of several weeks, months or years. Some types of generator system related conditions also follow load or operating temperatures. In these cases trending over a short period is needed to better identify conditions. This paper presents case studies of long term and short term trending of a generator high voltage system. Trending large motors is also presented.