process

Working of an Override Control  

Introduction The override control concept is a technique by which process variables are kept with in certain limits, usually for     protective purposes. Override control maintains the process in operation but within and under safer conditions.   Override control To illustrate override control, consider the simple process shown in Figure A hot, saturated liquid enters a process surge tank, and then it is then pumped into the process. Normally, the tank operates at the level shown, but if the level gets too low the liquid will not have enough net …

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How does a process control work?

Introduction. Process control is the automatic control of an output variable by sensing the amplitude of the output parameter from the process and comparing it to the desired or set level and feeding an error signal back to control an input variable. In order to produce a product with consistently high quality, tight process control …

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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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PROGRAMMING LOGIC DEVICES (PLC)

Introduction A digitally operating electronic apparatus which uses a programming memory for the internal storage of instructions for implementing specific functions such as logic, sequencing, timing, counting and arithmetic to control through digital or analog modules, various types of machines or process.In this session we are gonna discuss about basics of programming logic devices (PLC) …

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Different types of orifice plates

Introduction Orifice plates are mainly used for flow measurements. The orifice consists of a flat plate with a hole drilled in it. When a fluid passesthrough an orifice, the discharge is often considerably less than the amount calculated on the assumption that the energy is conserved and that the flow through the orifice is uniform and parallel.There are different types of orifice plates used for different fluids/process.  This reduction in flow is normally due to a contraction of the stream which takes place …

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