PRESSURE CONTROL LOOP TRAINER

 

PRESSURE CONTROL LOOP TRAINER

 

OVERALL SYSTEM CAPABILITY:

            Unitech Scales and Measurements Pvt. Ltd, Bangalore proudly announces the introduction of PRESSURE LOOP CONTROL training system for the Instrumentation and process control students and Industrial Technicians. This system is the outcome of our production team effort, which mainly suits to the syllabi of the Instrumentation courses.

             Typically, the training system is comprised by four independent process (like temperature, pressure, level and flow). Each work process is individually supported by a 100% compatible for the common PC which acts as the PID controller. This helps the student to visualize the process graphically on the screen.

             Each individual Process can equip the instrumentation and control laboratory to train students and industrial technicians on how to inspect, hands on experiment and tuning and the process control systems.

             Each process trainer is provided with one latest PC based software for independent operation. All the parameters of the process trainer are controlled by the software. ON-OFF, Proportional, Integral and Derivative control (PID control) are done by software. Since each process station is based on the PC.

Introduction:

            Proportional, integral, and Derivative controller or PID is a standard feedback loop component in industrial control applications. It measures an “output” of a process and controls an “input”, with a goal of maintaining the output at a target value, which is called the “setpoint”. An example of a PID application is the control of a process temperature, although it can be used to control any measurable variable which can be affected by manipulating some other process variable.

             The Controller compares a measured value from a process (typically and industrial process) are as follows

             Industrial processes are procedures involving chemical or mechanical steps to aid in the manufacture of an item or items, usually carried out on a large scale.

 Industrial processes are the key components of heavy industry.

             Most processes make the production of an otherwise rare material vastly cheaper, thus changing it into a commodity i.e. the process makes it economically feasible for society to use the material on a large scale. One of the best examples of this is the change in aluminum from prices more expensive than silver to its use in recyclable/disposable beverage containers.

             An industrial process differs from a craft, workshop or laboratory process by the scale or investment required. Most of the processes are complex and require large capital investments in machinery, or a substantial amount of raw materials, in comparison to batch or processes. Production of a specific material may involve more than one type of process.

             The difference (or “error” signal) is then used to calculate a new value for a manipulatable input to the process that brings the process’ measured value back to its desired setpoint. Unlike simpler control algorithm, the PU) controller can adjust process outputs based on the history and of change of the error signal, which gives more accurate and stable control. (It can be shown mathematically that a PID loop will produce accurate, stable control in cases where a simple proportional control would either have a steady state error or would cause the process to oscillates). PD controllers do not require advanced mathematics to design and can be easily adjusted (or “tuned”) to the desired application, unlike more complicated control algorithms based on optimal control theory.

 

Theory:

PROPORTONAL BAND

            The control algorithm that generates a linear control output proportional to deviation is called proportional action. in proportional action the amount of change in the measured valve (Or deviation) is expressed in percent of span that is required to cause the control output to change from 0 to 100% is called the proportional band.

INTEGRAL TIME

            With P action the measured valve will not necessarily become equal to the set the point, and a deviation will usually be present. The control algorithm that applies changes in output as long as a deviation exits, so as to bring the deviation to zero, is called integral action.

             When integral action is used, the parameter that determines how fast the output will in correspondence to some amount of deviation is referred to as integral time, and shorter the integral time, stronger the integral action (the greater the output rate of change). I action is usually used together with P action as P1 action, and due only to I became equal to that due only to P action.

DERIVATIVE TIME:

            If the controlled object has a large time constant or dead time, with P or P1 action alone there will be cases where the response will be slow, overshoot will occur, and the control system will be unstable. In order to achieve faster response and more stable operation cases one uses derivation action (D action) to apply an output component proportional to the input (deviation) rate of change.

             D action must always be used with P action time required with PD action. If a ramp input (constant rate of change input) is applied, for the output due to P action alone to become equal to that due to D action alone. The longer the derivation time, the stronger the derivation action.