Power plants operate over a large range of power; and, in cogeneration systems, the process requirements also control the operations of the plant. The plants are all part of a major grid and they supply the needs to meet the demand of the grid. Control systems are also closely tied up with the distributed control systems (D-CS) and condition monitoring systems (C-MS) with plant optimization software.

The traditional concept of maintenance in the utilities industry has been undergoing a major change to ensure that equipment not only has the best availability but also is operating at its maximum efficiency. There is a consistent trend in the utilities industry throughout the world to improve maintenance strategy from fix-as-fail to total performance-based planned maintenance. In practice, this calls for on-line monitoring and condition management of all major equipment in the plant. To reach the Utopian goal of just-in-time maintenance with minor disruption in the operation of the plant requires a very close understanding of the thermodynamic and mechanical aspects of plant equipment to be able to implement predictive maintenance programs.

The benefits of total performance-based planned maintenance not only ensure the best and lowest cost maintenance program, but also that the plant is operated at its most efficient point. An important supplementary effect is that the plant will be operating consistently within its environmental constraints.