Category: Mechatronics, Industrial Control & Instrumentation
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Hazardous Locations Classifications
A hazardous location is defined as a location where fire or explosion hazards exist due to the presence of flammable gases, vapors, or liquids, combustible dusts or ignitable fibers. Fire explosions can occur in a wide range of industrial environments … Read more
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Functional Safety in Instrumentation Systems (SIS, SIF & SIL)
Functional safety is the risk reduction provided by the functions implemented to ensure the safe operations of the process. The IEC 61508 standard covers functional safety of electrical/electronic/programmable electronic safety-related systems. The purpose of IEC 61508 is to use safety … Read more
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4-20 mA Transmitters (2-wire, 3-wire and 4-wire Types)
Background of 4-20 mA Signal Transmission Initially signal transmission was dominated by pneumatics before the advent of 4-20 mA signal standard. The standard was 3-15 psi pneumatic signal where the 3 psi was the ‘live zero’ and 15 psi represented … Read more
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What is a Smart Sensor?
A smart sensor is the integration of a sensor with an analogue to digital converter (ADC), a processor and digital to analogue converter (ADC) for actuator control. A typical application of a smart sensor set up is a temperature control … Read more
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Basic Features of Modern PID Controllers
Most modern PID controllers have the following features: Manual versus automatic modeOutput trackingSetpoint trackingAlarm capabilitiesProcess variable (PV) characterization and dampingSetpoint limitsOutput limitsPID tuning security Manual and Automatic Modes When the controller manually calculates … Read more
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Electromechanical Relays (EMR)
Electromechanical relay (EMR) is a device that uses an electromagnet to provide the force to close or open switch contacts i.e. it is an electrically powered switch. Figure (a) Parts of an electromechanical relay When the electromagnet (also called coil) … Read more
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Direct Digital Control (DDC)
In direct digital control (DDC) a single computer is able to carry out PID control for multiple loops at the same time make that loop data accessible between loops for purposes of cascade control, feedforward control, ratio control… Read more
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Digital PID Controllers
Digital PID controllers have replaced most pneumatic and electronic analog controllers in industrial control applications. Digital PID controllers are preferred over the analog types because they employ microprocessors which can execute multiple functions at ago hence they bring with them … Read more
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P&IDs and Loop Diagrams
Process and Instrument Diagrams (P&IDs), also called Piping and Instrumentation Diagrams and Loop diagrams are construction and documentation drawings that show the flow of the process and illustrate the instrumentation control and measurement instructions, wiring and connections to the process.… Read more
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Features of a Reed Relay
The reed like contacts of a reed relay are encapsulated in a small sealed glass tube that is evacuated or filled with an inert gas like dry nitrogen as illustrated in the figure below: Figure 1(a) reed relay The contacts … Read more