Actuators are known as movers which is used in opening and closing of the valves. There are various types of actuator they are pneumatic, hydraulic and electrical. Pneumatic and hydraulic actuators in the entire set they are more precise compared to the electrical actuators. The high end applications use hydraulic as they operate more accurately as per the command extended and the chances of faulty operation or extent of damage or regular repairs are very less.
The pneumatic actuators are used in medium but important areas they are less accurate and less costly compared to the hydraulic actuators and servicing of these actuators is to be done regularly.
The electric actuators are less accurate and very cheap among the three and are used in higher number in the thermal power plants.
The hydraulic actuators are generally used in very important areas of thermal power plant where high and fast response is needed such as hpbypass and lpbypass. These are very crucial and there accurate response saves plant under shutdown and startup. The malfunction in these areas provides disastrous results for a thermal power station.
The pneumatic actuators are generally used in lesser but important applications such as feed water station and drain valves of the heaters.
The electrical actuators are used in every area of a thermal plant and are used individually or in support of the hydraulic and pneumatic actuators.
The selection of the actuators mainly depend on the reliability to work in various temperature areas as the thermal plant consists of very high temperatures. It also depends on the reliability and the durability. Specially actuators are used in combination with the control valves.
The major problems always arises with the electrical actuators as these contains number of electrical components which will be damaged more frequently compared to the pneumatic and hydraulic actuators or control valves. The major problems that arises are limit switch adjustment, pcb card problem, transformer card damaged, fuse blown off, cable shortage.
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