Publisher Summary This chapter discusses the continual optimization of control systems in thermal power plants. The 500 MW Unit No. 5 at the Tata Electric Companies Trombay Thermal Power Station was commissioned in January 1984. Several difficulties and constraints were experienced while carrying out the detailed engineering for this unit and in particular its instrumentation and control systems. After stabilization of the unit, further measures to improve and enhance the reliability and performance of the unit by fine tuning of the control systems have been undertaken. At the time of undertaking the 500 MW Unit 5 Project at Trombay, several difficult and critical decisions had to be made during its conceptualisation and formulation stage. The factors which contributed to make the exercise a tough and complex one are presented. These include: (1) large size, (2) giant leap in technology, (3) quest for state of the art technologies, (4) inherent flexibility for subsequent upgradation, and (5) optimization of running and fixed costs. To override the operational limitations and uncertainties arising out of the addition of a disproportionally large size unit to the grid, the following strategies were employed to ensure high reliability and availability—(1) co-ordination between utility and consultant, (2) study tours, (3) training and inspection at manufacturer's works, and (4) participation in erection and commissioning activities. The 500 MW Unit 5 is equipped with four induced draft fans (2050 KW each), two forced draft fans (2700 KW each), and two primary air fans (2750 KW each). Consequently, the efficient and optimal operation of these fans particularly at part loads offers an attractive area for enhancement of the overall unit efficiency.