An electric valve actuator in simple terms is an electric device that moves a valve. You can say that a solenoid valve falls in this category but in our case, we are referring to an electric motor separate from the valve. The electric motor is typically housed in an enclosure with a drive gear and two position limit switches as a minimum.
Centralized control of a plant involves the control of its services such as water, steam, air, fuel, electricity, etc. Of these, all except electricity involve piping, and their control involves valves, which are usually power operated.
Where a valve must move to a known position, in the event of electricity failure during power failure conditions, stored energy is essential. If the valve is normally remote controlled, the remote control system will be electric for the following reasons:
When actuator manufacturers classify their products duty performances they typically follow and meet a particular standard. One such standard is EN-15714-2 (Industrial valves – Actuators – Part 2: Electric actuators for industrial valves – Basic Requirements). We make reference to this standard in our explanation below.
Electric Actuator Basics: Understanding the differences between On/Off, Floating, Two Position and Modulating Control
Generally, to understand these types of control, you must start with the elements of control. These elements are considered the control loop. One of those elements is the actuator. Below, the differences between On/Off, Floating, Two Position and Modulating Control in respect to actuator control are explained.