Control System

What is Supervisory control?

Introduction There are a lots of control sytems like cascade control ,feedback control,feedforward control,split controls etc used in the process industries in this session we are gonna discuss about Supervisory control In a manually-controlled process, a human operator directly actuates some form of final control element (usually a valve) to influence a process variable. Simple automatic …

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Pen recorders

Recoders are device used to record and store data into paper or any other reading device. Industrial recorders monitor the changes over time in process measurement signals, and provide a permanent record of those changes. functions can be classified into measuring, processing and recording. In self-balancing recorders, measuring and recording are mainly accomplished by servomechanisms.   Pen …

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DIFFERENCE BETWEEN FEEDBACK AND FEEDFORWARD CONTROL LOOPS

INTRODUCTION There are so many control loops in the industries nowadays.In this session we are going to discuss about difference between feedback and feedforward controls loops FEEDFORWARD CONTROL LOOPS A feedback control loop is reactive in nature and represents a response to the effect of a load change or disorder. A forward control loop, on the …

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WHAT IS RATIO CONTROL ?

RATIO CONTROL  A ratio controller is a special type of feed forward controller where disturbances are measured and their ratio is held at a desired set point by controlling one of the streams.   Ratio control is used when two fluids must be mixed together in a specific ratio.  A practical way to do this …

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what is cascade control?

A simple control system drawn in block diagram form looks like this:   Information from the measuring device (e.g. transmitter) goes to  the controller, then to the final control device (e.g. control valve), influencing the process which is sensed again by the measuring device. The controller’s task is to inject the proper amount of negative feedback …

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BASICS OF ON/OFF CONTROLLER

Introduction In control theory, an on/off controller, also known as a hysteresis controller, is a feedback controller that switches abruptly between two states. These controllers may be realized in terms of any element that provides hysteresis. They are often used to control a plant that accepts a binary input, for example a furnace that is either completely …

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BASIC CONTROL PRINCIPLES

 INTRODUCTION Control of the processes in the plant is an essential part of the plant operation.The level of the boiler must be kept within a certain range. The heat transport pressure is another critical parameter that must be controlled. If it is too high the system will burst, if it is too low the water …

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Working of control valve

Introduction The control valve is a controlled device that regulates the flow of a liquid or gas in a system. This regulation is accomplished by the varying resistance that the valve introduces into the system as the valve is stroked. As the valve modulates to the closed position the system pressure drop shifts to the …

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