Large turbo- and hydro-generators are directly cooled with high purity water for efficient heat transfer from the coils. Plant operators, engineers and chemists don’t get a lot of experience with troubleshooting, as operation can be trouble free for decades. However, when a problem arises, it can happen rapidly. The reason is often plugging of the stator cooling water system (SCWS) copper hollow conductors. This can result in forced outages or major generator failures and can occur within weeks — or years — after first indication. Thus, proper instrumentation will support plants to early detect a malfunctioning cooling water system and can provide sufficient time to take effective corrective actions.
The focus is on how both the SCWS and its internal instrumentation, along with enhanced monitoring techniques, can help facilitate a more proactive approach to manage corrosion effects such as hollow conductor plugging. Different basic OEM supplied instrumentation for both high- and low-oxygen systems are discussed and benefits thereof are outlined as well as “state-of-the-art” instrumentation is presented. Industry examples are demonstrating the benefit of proper instrumentation as early detection of copper oxide plugging prevented power plants from forced outages and costly rewinds. Subsequently, full cooling capacity was restored by online removal of the copper oxides.