Weak current College】 【electric actuator selection considerations.

First, according to valve type electric actuator
Valve type quite a bit, it works too, generally to turn the valve plate angle, lifting the valve plate, and other ways to achieve open and close control, and electric actuator mating time should first select according to the type of the valve actuator.
1. point-travel electric actuator (corner < 360 degrees)
Electric Actuator output axis of rotation is less than a week, i.e. less than 360 degrees, usually 90 degrees on the realization of process control valves open and close. Such electric actuator installation interface method is divided into direct-attached type, the base two crank.
A) direct-attached: refers to the output shaft of the electric actuator and valve stem in the form of a direct-connect installation.
B) base crank: refers to the output shaft connection by crank and the valve stem.
This type of electric actuators for butterfly valve, ball valve, plug valve, etc.
2. multi-turn electric actuator (corner > 360 degrees)
Electric Actuator output axis of rotation is more than a week, that is greater than 360 degrees, it will normally take many laps to achieve process control valves open and close.
This type of electric actuators for gate valves, globe valves, etc.
3. direct-travel electric actuator (direct line)
Electric Actuator output axis of movement to the straight line motion mode, not a rotation.
This type of electric actuators for single seat control valve, double seat control valve and so on.
Second, according to the production process control requirements determine Electric Actuator control mode
Electric Actuator control mode General split into switching (open-loop control) and Regulation (closed-loop control).
1. switch (open-loop control)
Switch actuator on the valve normally open or closed control, valve or in the fully open position, either in full off position, this type of valve is not required to carry out precise control of the media flow.
Of particular note is the switching actuator due to structural forms of different also can be divided into separate structure and integrated structure. Selection of required to address, or often occur in the on-site installation time and control system does not match conflict, etc.
A) split structure (usually called the common type): control unit with electric actuator, actuator cannot separate the valve control, required plus control unit can control, General external use controller or control cabinet form.
The disadvantage of this structure is not easy to install the system as a whole, increasing the wiring and installation costs, and prone to failure, when a fault occurs, not easy to diagnose and repair, price is not ideal.
B) integrated structure (often referred to as a whole): control unit with electric actuator packaged as a whole, without the need for external distribution control unit can be reality in-place operation, remote control simply output-related information to it.
The advantage of this structure is to facilitate the installation of the system as a whole, reducing wiring and installation costs, easier to diagnose and troubleshoot. But the traditional integration structures also have many imperfections, the smart electric actuator, the smart electric actuator followed will be explained.
2. adjust the type (closed-loop control)
Regulation-type electric actuator not only with switch integrated structure and precise regulation of the media flow. Because of the function, it also precise control of the valve, from the scope of their works in this not for detailed instructions. The following regulation-type electric actuator selection needed if there is a brief description of the arguments made.
A) control signal type (current, voltage)
Regulation-type Electric Actuator control signal generally has a current signal (4-20mA, 0-10mA) or voltage signal (0 to 5V, 1 ~ 5V), when you need to clear the selection of control signal type and parameters.
B) work (electric drive type, power off)
Regulation-type electric actuator works normally electric opening (in 4 ~ 20mA control, for example, electric drive type refers to the corresponding signal is 4mA valve clearance, 20mA corresponding is valve open), and the other for power off-(4-20mA control, for example, electric drive type refers to the corresponding signal is 4mA valve open, 20mA corresponding is valve clearance). the General selection required a clear work forms, many of the products after the factory and cannot be modified, Ogilvy valve control production of intelligent electric actuator can be modified at any time by setting the scene.
C) breaking, protection
Breaking, protection refers to the line, such as fault control signal is lost, Electric Actuator control valves open and close to the set of values, common protection value is full, full off, hold position three situations and difficult to modify after the factory. Ogilvy valve control production of intelligent electric actuator can be set through the site, and for flexible changes can be set anywhere (0 ~ 100%) for the protection of values.
Third, according to valve required torque determine electric actuator output torque
Valves open and close the torque required to determine electric actuator selection much output torque, generally by users or valve manufacturers themselves matching, as the actuator manufacturers only the output torque of the actuator, the valve is normally responsible for opening and closing the desired torque from the valve diameter size, work pressure, and other factors, but because the valve manufacturers processing precision, Assembly process distinct from the different manufacturers with the specifications of the desired torque valve also differ, even with a valve manufacturers of the same specification valve torque also vary, elected type actuator torque selection is too small it will cause does not close the valve, actuator required to choose a reasonable range of torque.
4. According to the selected actuator determine electrical parameter
Because different actuator manufacturers of electrical parameters vary, so the selection is generally required to determine the electrical parameters, mainly motor power, rated current, secondary control circuit voltage, are often the result of negligence, control system and electric actuator parameter does not match the result in time off trip, fuses, thermal overload relay protection fault-off, etc.
5. According to the used select enclosures, explosion-proof rank
1. shell IP protection, etc.-Level 2. explosion-proof rank