Power Plant Instrumentation and Control Handbook

4. Actuators

4.0. Introduction

An actuator in FCEs accepts the external signal from the control system in response to the same to regulate the motion (or position) of the FCE to modify its position and achieve the desired control. It has two functions: (1) to accommodate various accessories associated with the assembly so that desired movement of the FCE can be achieved and (2) to respond to the external control signal. In power plants all three types of actuators, electrical, hydraulic, and pneumatic, are used. In many plants electrical actuators with power amplifiers are used for regulating functions to overcome excess inertia problems associated with electrical actuators. However, electrical actuators are used more often in ON/OFF functions ...