Direct Digital Control: Developments in digital electronics have led to many industrial processes being computer controlled. The first system used was Direct Digital Control (DDC), in which a computer measured each variable in the process,…
Choice of Electronic Signal Transmission: The range of air pressure used for Signal Transmission in pneumatic system is limited by the dynamic operating range of the pneumatic devices used. But the choice of electrical transmission…
Temperature Controls using an Analog Electronic Controller: A Temperature Controls scheme using an Analog Electronic Controller of Fig. 21.14 is as shown in Fig. 21.16. The temperature setting, derived from a slide wire, is compared with the…
Analog Electronics Process Controllers: An Analog Electronics Process Controllers must be capable of providing one or more of the three main methods of control, namely, Proportional, Integral and Derivative. The circuits described in this section…
Define Offset Error: Define Offset Error - Proportional control action is characterized by a permanent residual error in the operating point of the controlled variable when a change in load occurs. This error is called…
Proportional Controller: In many processes, the cycling that occurs with the two position ON—OFF control is undesirable. Steady process controlled in the absence of noises, is possible when the controlled variable is a continuous function…
On Off Controller or Two Position Controller: The On Off Controller or two position controller is the simplest, cheapest and the most used controllers. It is used in domestic heating systems, refrigeration, water tanks, etc.…
Step Function Response: The step function response consists of applying an instantaneous change in the control means and then recording graphically the result of the change on the measured variable. This graphical record obtained in…
Basic Automatic Control: Multivariable systems are used more commonly in this age of Basic Automatic Control. Control parameters are becoming more complex by the day and the range of applications wider. In such complex systems,…
Standing Wave Ratio Measurements: Standing wave are created along the length of a transmission line due to the mismatch between the characteristic impedance Z0 and the terminating impedance of the transmission line. The actual voltage…
