Tag: process control
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Process Instrumentation Diagnostics & Communication Interfaces
There are various technologies that are available that help plant automation personnel to obtain diagnostic data which inform the type of maintenance to be undertaken. For example, using Distributed Control System (DCS), PC software tools, or handheld communicators, plant automation professionals can diagnose the health of an instrumentation device while it is in the line.…
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What is Optimal Control?
Optimal control is whereby the requirements are formulated as either the minimization of a cost index or the maximization of a performance index of an operational control system. Optimal control is utilized in a number of disciplines such as aircraft and spacecraft, satellites and aerospace, communications engineering, robots and robotics, electric drives, power systems, computer…
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Pneumatic Signal Transmission System
Signal transmission in process instrumentation and control systems is largely done via electrical transmission but there are a few areas where pneumatic transmission of signals is vital especially where electrical signals or sparks can ignite combustible materials for example in petroleum refineries. In pneumatic transmission systems, the measured quantity (pressure, level, temperature, and so…
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How Redundancy is Achieved in Process Plants
In similar way to electronic systems, redundancy is extensively employed technique for enhancing the reliability of many industrial plants and processes. Because many process plants units such as pumps, valves and compressors involve moving parts, they are prone to wear and therefore require periodic inspection and maintenance. Where the plant is required to operate continuously,…
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Phase Locked Loop High Precision Motor Speed Control System
AC generators can be utilized in high precision control systems. The AC generator rotor is rotated by the rotating shaft (i.e. the shaft from the motor being controlled). The output AC frequency is proportional to shaft speed. Zero crossings per time interval can be counted to determine speed for a simple control system. If high…
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Principle of Operation of Magnetostrictive Position Sensors
Magnetostrictive sensors detect the location of a magnetic ring that slides along a conductive metal tube; in other words this sensor operation utilizes the effect of a magnetic field on magnetostrictive wire to function. The figure below illustrates a Magnetostrictive position sensor: To detect the position of the magnet (in this case, an electromagnetic created…
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How to Connect Discrete Sensors to PLC Inputs
Discrete Sensor Outputs Basically sensor outputs can be categorized into two types: discrete also referred to discrete or logic and proportional also called analog. Discrete sensors supply a single logical output (1 or 0) e.g. a flow switch used to detect the fluid flow through a pipe whereas proportional/analog sensors provide an analog electronic…
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NAMUR NE 107 Standard for Modern Instrumentation Diagnostics
NAMUR NE 107 is a standard adhered to by manufacturers during the design and fabrication of instruments. NAMUR NE 107 provides status signals that communicate clear messages and remedies. These status signals or diagnostic codes are categorized into four standard icons and colors making it easier for users to comprehend them irrespective of the manufacturer…
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Steam Conditioning Valves – Features, Advantages & Applications
The Work of Steam Conditioning Valves & Why they are used in Industrial Processes Typically in an industrial set up, it may be necessary downstream of the main process application of superheated steam to reduce its pressure and temperatures to enhance the process efficiency, protect the equipment or perform other processes. This can be accomplished…
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What is the Function of a Steam Desuperheater?
Whereas superheated steam offers an excellent source of energy for mechanical power generation, in most cases, steam at greatly reduced temperatures, near saturation, proves a more desirable commodity especially for most heat-transfer applications. Precise temperature control is required to enhance heating efficiency; eliminate unintentional superheat in throttling processes; or to protect the downstream product or…