Author: John Mulindi
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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 many advantages in addition to their ability to network with PC workstations and other controllers…
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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. The sections or subsystems of the process that are usually shown are called loops. A…
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RF Power and Voltage Measurement
RF system’s output power level is often the key factor in the design and ultimately the performance of virtually all radio frequency and microwave equipment. For the measurement of average power, a sensor along with a calibrated power meter is connected with the RF transmitter. Initially, if the output of the sensor is switched OFF…
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Ratio Control
In some processes, it is a common requirement for two flows to be kept in precise ratio to each other for example, a gas or oil and air in combustion control, and reagents being fed to a chemical reactor hence the need for ratio control. In simple ratio control, one flow is declared to be…
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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: The contacts are activated by an external magnetic field. The contacts are either dry or mercury-wetted. Mercury-wetted contacts have a thin…
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Feedforward Control
Feedforward control is based on principle of pre-emptive load counter-action i.e. if all major loads (i.e. disturbances) on a process variable are monitored, and their effects on that process variable are well-understood, a control system programmed to take the appropriate action based on load changes will shield the process variable (PV) from any adverse effect.…
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Benefits of Cascade Control
We know very well that closed loop control provides increased performance over open loop control. So it would be rational to expect benefits from adding inner control loop around plant items that have degrading overall performance. The Figure (a) below illustrates a typical example of a cascade control: In Figure (a) above, the outer loop…
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Solid-state Relays (SSR) Features and Operation
A solid-state relay (SSR) is a purely solid-state device used for turning ON and OFF AC loads such as motors. Features of a Solid-state Relay Let’s consider the figure below: Physically, the SSR is packaged in a box with four electrical terminals: two input terminals and two output terminals. The input or control voltage of…
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Basic Facts about Quantum Computing
Quantum computers employ the laws of quantum mechanics to process data. Quantum mechanics in itself is the study of matter and light on the atomic and subatomic scale. Quantum material behaves according to the laws of quantum mechanics. At the quantum level laws of classical physics largely don’t apply instead concepts such as probabilistic computation,…
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What is Motion Control?
Motion control generally refers to an open loop or closed loop electromechanical system in which things are moving. A motion control typically consists of a motor, mechanical parts that move and often feedback sensor(s). Typical examples of motion control applications are: Servomechanisms Numerical control machines Industrial robots Variable speed drills Digital torque wrenches Hard-drive head-positioning…