Integrated Condition Monitoring System Strategy at CEMIG

Abstract

The condition monitoring section at the Brazilian power utility CEMIG is implementing an effective condition-based maintenance strategy that ensures the over 40 power plants spread out over a large area operate with minimal downtime and at a minimal maintenance cost. The condition monitoring system needed to fulfil CEMIG’s needs for the larger plants did not exist, so it was decided to integrate several monitoring systems for this purpose. A computerized, permanently installed vibration monitoring system is planned to be integrated to other systems dedicated to specific periodic machine condition monitoring applications (e.g. air gap monitoring, oil analysis, magnetic flux monitoring, partial discharge analysis). This integrated monitoring approach results in a distributed system with a single system technique for alarm handling, and a user interface and database for analysis, diagnosis and fault correlation. The vibration monitoring system will also be extended for importing process data from the existing distributed supervisory and control system for monitoring calculated performance parameters such as efficiency and head. Testing is also under way for investigating the possibility of more effectively monitoring cavitation without purchasing a separate stand-alone system. Several of the larger plants at CEMIG will eventually be remotely monitored this way, but this paper focuses primarily on the monitoring system, strategy and current operating experience at the Nova Ponte hydroelectric power station. Even before integrating the other monitoring systems, the installed condition monitoring section played a large role in ensuring the plant operates safely, cost effectively and with maximum availability. Although the monitoring system is installed at a hydro-electric power station, some examples are briefly given on how the same integrated monitoring system approach could equally be advantageous in detecting and/or diagnosing certain faults within gas turbines and compressors.