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     Conductor  is an object or type of material that allows the flow of charge ( electrical  current) in one or more directions. Materials made of metal are common  electrical conductors . A semiconductor is a solid substance that has a conductivity between that of an insulator and that of most metals , either due to the addition of an impurity or because of temperature effects . Devices made of semiconductors, notably silicon , are essential components of most electronic circuits. A Silicon crystal is the purest form of Silicon.  A silicon atom has four valence electrons, and thus it requires another four to complete its outermost shell. This is achieved by sharing one of its valence electrons with each of its four neighboring atoms. Each pair of shared electrons forms a covalent bond. The result is that a crystal of pure or intrinsic silicon has a regular lattice structure, where the atoms are held in their position by the cova...

In last blog we learned about how we can get Relative Gain Array by two stages. If you haven't gone through yet, click below link: Multi-variable System In this blog, we will analyze different conditions for Relative Gain Array. RGA provides a quantitative criterion for for selection of control loops that would lead to minimum interaction among the process. Direct & Indirect Effects of control loop interaction Let us open the loops and detach the controllers from the process. Let us keep u2  constant and introduce step input in u1 . That would yield a static gain and indicate direct effect of input on output. Let us now close only the loop 2 and attach the corresponding controller with the process. Let us now introduce a step input in u1 while maintaining y2 at its desired setpoint through the loop 2 controller. That would yield another open loop gain and indicate direct as well as indirect effect of u1 on output y1 . Let's analyze the following conditions for RGA: D...

What is Multi-variable System? As name suggests, multi-variable means multiple parameters included in system. The control system which have more than one input & more than one output, which is called Multi-variable System .  This kind of system have as many inputs and outputs as needed to control the process. In multi-variable system, the interaction in between variables are very strong. If any disturbance occurred, then response of the system will change. The changes in signal path can be in two way, direct & indirect. Let's learn it with example; Example of Process As above shown, consider the process having two inputs u1, u2 and two outputs y1, y2. Suppose if any kind of change occurred in input u1, it may have two effects. Changes in output y1 ( Direct effect ) via measured value interaction Changes in output y2 ( Indirect effect ) via control loop interaction This process interaction cause potential problems in systems; It will destabilize the closed loop system T...

What is Polarography? Polarography is the measurement of the current that flows in solution as a function of an applied voltage . Polarography is a voltammetric technique in which chemical species (ions or molecules) undergo oxidation (lose electrons) or reduction (gain electrons) at the surface of a dropping mercury electrode  (DME) at an applied potential.  The actual form of the observed "polarographic wave" depends upon the manner in which the voltage is applied and on the characteristics of the working electrode.  The working electrode is often a Dropping Mercury Electrode (DME), and the polarographic wave thus has oscillations imposed on it from the variations in mercury drop size.  As above, you can see that, as variation in potential in graph (A), we can see variation of current with respect to potential in graph (B). Those are graph of polarograph. then, let's see how that works ! Principle: Polarography consists of electrolysing a solution of an elect...

The implementation of the PID controller has evolved from early mechanical and pneumatic designs to analog circuits using transistors, and lately to the microprocessor and digital systems. The digital PID so designed is based essentially on architectures including multipliers, adders, and some other logic circuits. Another advantage of digital control is that the error signal is first sampled and the controller output is computed numerically through a digital processor. Control action = past control action + correction by controller  For PID controller Lets consider the following diagram   Input = e(t)   Output = u(t)    The transfer function in the PID controller in continuous time is given by Equation 1 Where k= gain Ti = integral time Td = derivative time Taking Laplace to transform on both sides we obtain the continuous controller Equation 2 Write the above equations in gain terms Equation 3 To implement in digital write Equation 3 in z – transform...

In the previous blog, we learn about instrumentation documents overview. In that document's example, we saw types of icons & symbols.  In this blog, we will learn about it in detail. If you haven't seen the previous blog, then click down below: Instrumentation Documents Overview As per PFD, P&ID, and other documents, there is variation in lines, equipment symbols, valve types, measurement devices, symbols for functional diagrams, etc. Line Types : Process/Instrument Line connections : Instrument Bubbles : Process Valve Types : Valve Actuator Types : Liquid Level Measurement Devices : Flow Measurement Devices (flowing left-to-right) : Process Equipment : Functional Diagram Symbols : Single-Line Electrical Diagram Symbols :  Fluid Power Diagram Symbols : That's it for this blog. Thanks & Keep Learning.