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Vibration Monitoring is a Key Tool in Condition-Based Maintenance for Hydroelectric Generators

Generators at a hydroelectric plant.
Published in December 2011 by the Hydro-Power Advancement Project (HAP), Best Practice Catalog - Machine Condition Monitoring is an 18-page study prepared by the Chattanooga-based engineering and consulting company Mesa Associates, Inc., and Tennessee's Oak Ridge National Laboratory, representing the U.S. Department of Energy.

The work opens with a brief synopsis of the needs of U.S. hydroelectric installations and potential advantages of vibration monitoring for predictive maintenance:
"Condition monitoring of hydroelectric power generating units is essential to protect against sudden failure.  Fault development can occur very quickly.  Many hydro units are located in remote areas making regular inspection difficult.  It is required to have a monitoring system that continuously checks machine condition, remotely indicates the onset of a fault, and provides the possibility of preventive automatic shutdown."
"Hydroelectric turbine-generators are subject to forces and operating conditions unique to their operation and configuration.  They typically operate at low rotational speeds.  Their physical mass and slow rotational speeds give rise to large vibration amplitudes and low vibration frequencies.  This requires a monitoring system with special low frequency response capabilities."
In the study it was noted that "Vibration analysis was typically performed by a mechanic or the operator by observing a dial indicator.  This is still the only method in older facilities.  Recent developments in vibration sensor, data acquisition, and analysis technologies, however, are making vibration analysis cheaper, easier, and more widely available."

One special innovation of interest is the use of "Models [to] create virtual sensors where physical sensors are not able to be installed.  An example is where real data from physical sensors mounted on the bearings at the shaft ends, is used to create a virtual sensor for mid-span vibration."

Monitor placement, measurement, and output are discussed for hydro turbines and generators, and the importance of integrating their output with the rest of the facility's instruments and controls for ease of reference and integrated use.

The study concludes, "The best way to gain the benefits of a monitoring system is to take advantage of the economic opportunities offered by various modernization, refurbishment, and new projects to introduce the system and to adapt maintenance practices accordingly.  The monitoring system is a major input to a condition-based maintenance program and is a key contributor to capitalizing on high market prices."

"The cost of the monitoring system is low compared with the cost of a new power plant.  A new plant should automatically be equipped with a monitoring system to minimize maintenance outage periods and to help the unit owner stay well-informed of the condition of the equipment."

Photo by Wikisanchez (Own work) [Public domain], via Wikimedia Commons

1 comment :

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