Valve Electric Device Development Prospects

The valve electric device is a driving device that does not lack the valve programming, automatic control and remote control. The movement process can be controlled by the size of the stroke, torque or axial thrust. Because the operating characteristics and utilization of electrical equipment valves depend on the type of valve, operating standards of the equipment, and the orientation of the valve on the pipeline or equipment.

Electric devices generally consist of the following components:

The special motor is characterized by strong overload capacity, large starting torque, small moment of inertia, short-term and intermittent operation.

Slow down the structure to reduce the output speed of the motor.

Travel control organization to regulate and accurately control the opening and closing position of the valve.

The torque constrains the organization to condition the torque (or thrust) so that it does not exceed a predetermined value.

Manual, electric switching organizations, manual or electrically operated interlocking organization.

The opening indicator is used to show the position of the valve in the opening and closing process.

First, according to the production process control requirements determine the electric actuator control method

1. Switch-type (open-loop control) switch-type electric actuators typically operate on or off the valve. The valve is either fully open or fully closed. This type of valve does not require accurate control of the media flow.

It is particularly worth mentioning that switch-type electric actuators can be divided into separate structures and integrated structures due to different structural methods. This must be clarified when selecting a type, otherwise there is often a mismatch between the on-site equipment and the control system. A) Split structure (commonly referred to as ordinary type): The control unit and the electric actuator are separated. The electric actuator cannot complete the control of the valve alone. It is necessary to add an operating unit to complete the control. Generally, an external controller or a control cabinet method is used. Supporting. The disadvantage of this structure is that it is inconvenient for the whole system of the system, increasing the cost of wiring and equipment, and it is easy to have problems. When the fault occurs, it is inconvenient to diagnose and repair, and the cost-effectiveness is not aspiration. B) Integrated structure (generally referred to as the overall type): The control unit and the electric actuator are packaged into one body, and the actual operation on the ground is possible without the external control unit. The long-distance operation can be performed only by outputting the related control information. The advantage of this structure is to facilitate the entire system of equipment, reduce wiring and equipment costs, simply diagnose and eliminate problems. However, traditional integrated structural products also have many imperfect localities, so intelligent electric actuators are produced. 2. Adjustable (closed-loop control) conditioning type electric actuator not only has the function of switch-type integrated structure, but also can accurately control the valve and regulate the flow of medium.

A) Types of control signals (current, voltage) Actuation signals of regulating type electric actuators generally have current signals (4 to 20MA, 0 to 10MA) or voltage signals (0 to 5V, 1 to 5V), and need to be clearly controlled when selecting models. Signal type and parameters.

B) Operation method (electrically-opened type, power-off type) The operating method of the electric actuator for adjustment is generally electric open type (in the case of 4 to 20 MA for example, the electric open type means that the 4MA signal corresponds to valve close, 20 MA corresponds to The valve is open, and the other is the power-off type (for 4-20MA control, the open type refers to the 4MA signal corresponding to the valve open, 20MA corresponds to the valve closed).

C) Loss of signal maintenance Loss of signal maintenance means that when the control signal is lost due to faults such as lines, the electric actuator will open and close the control valve to the set maintenance value. The common maintenance value is full-open, full-close, and in-situ three. Electrical equipment based on the use of the environment and explosion-proof level requirements, the valve's electric device can be divided into ordinary type, outdoor type, explosion-proof type, outdoor flameproof type.

Second, Select electric actuator according to valve type

1. Angular stroke electric actuator (rotation angle "360 degrees") applies to butterfly valves, ball valves, plug valves, etc. The rotation of the output shaft of the electric actuator is less than one week, that is, less than 360 degrees, generally 90 degrees to complete the valve opening and closing process control. Such electric actuators are divided into two types: direct connection and base crank, depending on the device interface method.

A) Direct connection: refers to the method of directly connecting the output shaft and stem of the electric actuator.

B) Base Crank Type: Refers to the way the output shaft is connected to the stem through the crank.