Electric actuator:

Actuator are used for the automation of industrial valves and can be found by process plants of all types:

They are in wastewater treatment plants, power plants and refineries, used. This is where they play an important role in the automation of process control. The valves are automated differ both in design and dimension. The diameters of the valves range from a few centimeters to a few meters.

Classification of actors according to their movement Travel is the distance between the closure element into the valve cover fully open or close the valve. Typical elements are closed butterfly, globe or gate valve discs. These three elements are necessary for completion of the three basic movements to cover the trip. The butterfly valve disc through a 90 ° rotary movement of the end position OPEN to run the world is the valve plate by a rather short linear motion (stroke), while the gate valve plate movement encompasses the entire diameter of the valve operation. Every movement requires a special kind of drive type.

Electrical actuator on a gate valve Rotary Actuators Rotary actuators for the automation of multi-turn valves that are required. One of the most important representatives of this kind is the slider.

The basic requirements for rotary actuators are in the standard EN ISO 5210 described as follows:

"A rotary actuator is an actuator which transmits the torque to the valve at least one full revolution. It is capable of withstanding thrust." A valve is mounted to the gate valve plate. The rotary actuator moves the gate valve plate from OPEN to CLOSED and vice versa via a threaded socket. To cover travel, complete valve, the so-called valve lift, the actuator has to meet - depending on the valve - a few or several hundred rotations. Because of their construction has the impact of electric drives, set in contrast to those of their pneumatic counterparts, no limits.

Therefore, slides are entirely automated by electric multi-turn actuators. The rotary actuator must be in a position to the weight of the gate valve plate resisted by the valve port, the interface with the valve. This will be achieved in the second sentence of the definition expressed. Slide may have a diameter of approx. 4 centimeters to several meters. The torque requirement for multi-turn solutions ranges from approx. 10 N m to 30,000 N m Electric rotary actuator to a flap Rotary actuators Rotary actuators are required for automating swivel valves.

Important members of this type are designed valves and cocks. The basic requirements for rotary actuators are in the standard EN ISO 5211 described as follows: "A rotary actuator is an actuator, which transfers torque to the valve is less than one full revolution.

It need not be possible to shear forces." Less than one full revolution usually means a pivoting motion of 90 °, but there are some species that a valve different swing angles, such as two-way valves. The closure elements in rotary actuators are always supported by the valve housing, ie the weight of the closing act rather than part-turn actuator. This will be achieved in the second sentence of the definition expressed.

Part-valve diameters of a few centimeters to several meters. The torque requirement for the operation of the closure element has a comparable range of about 10 N m up to several 100,000 N m. Electric drives are unrivaled for large diameter valves with high torque requirements. Linear There is currently no international standard for describing linear or linear units.

Automate a typical representative of the valves is the giver. Exactly how is the plug in the bath is forced into the runoff, hold the plug in the plug seat by a stroke. The pressure of the medium acts on the connectors while the unit has to be able to push the same amount of thrust, hold and pull the plug type against this pressure.

Most of the used linear actuators are pneumatic diaphragm actuators. They are characterized characterized by a simple design principle and are therefore cheaper. The compressed air supply is a prerequisite for their use. If this is not possible to recommend the use of thrust units is, which can be easily supplied with electricity.

Design:

Electric rotary actuator with controls Motor

(1) Robust three-phase asynchronous motors are mostly used as a driving force, used for many applications including single-phase AC or DC-motors. These motors are specially adapted for valve automation, since they may require higher torque from a standstill than conventional engines, a necessary condition to topple sticky valves. The drives are expected to operate even under extreme environmental conditions, but they are usually not for the continuous operation of the engine, as is the excessive use of heat. Limit and torque sensors

(2) The limit switching action, the travel and signals, was achieved when an end position, the torque circuit measures the torque in the valve. When exceeding a certain limit, this is signaled in the same way. Drives are often equipped with a remote transmitter position, the valve position as a continuous current or voltage signal shows safe. Gearing

(3) Often, a worm gear is used to reduce the high output speed of the electric motor. This enables a high reduction in the transmission stage, resulting in low efficiency, which is desired for the drives. The transmission is thus self-locking means preventing the unwanted and undesirable changes in the valve position by the action of closing the valve element. This is of great importance for rotary actuators, which are axially loaded with the weight of the gate valve plate. Valve attachment

(4) The valve system consists of two elements. First, the flange used to drive down into their counterparts get in touch at the valve side. The higher the torque is transferred, the greater the flange is required. Second: The drive type used to transmit the torque and the thrust from the actuator on the valve stem. Just as there are a variety of valves there are a variety of valve attachments. Dimensions and design of the valve flange and valve attachments are in the standards EN ISO 5210 for rotary actuators or EN ISO 5211 for rotary actuators. The design of the valve for linear systems is usually based on DIN 3358. Manual operation

(5) In the basic version of most electric motors are equipped with a hand wheel to operate the drive during start-up or power failure. The handwheel does not move during engine operation. Actuator Control

(6) Both drive signals and commands of the DCS are processed into the actuator control. This task can be considered, in principle, by which external controls, such as a PLC. Modern drives are integrated controller, the process signals directly on the spot without delay. The controls include the substation is needed to control the electric motor. This can either reversing contactors or thyristors, which are not subject to as an electrical component, the mechanical wear. Controls use of the substation to the electric motor on or off, depending on the signals or commands to change the present. Another task of the actuator control system is the DCS with feedback, such as provision of a valve end position is reached. Electrical Connection

(7) The supply of the motor and signal cables for the transmission of commands to the drive and send feedback about the status of the drive are connected to electrical connection. The electrical connection is ideally designed as a plug / connector. For maintenance purposes, the wiring can be easily disconnected and reconnected. Fieldbus connection.

(8) Increasingly Fieldbus technology is used for data transmission in process automation applications. Electric actuators can therefore be equipped with all standard fieldbus interfaces, used in process automation. Special connections are for connection of fieldbus data cable needed ..