Measurement of Power

Define Offset Error

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 the OFFSET. The offset can be reduced by selecting higher value of controller gain (KP) corresponding to narrow bandwidth. Figure 21.6 …

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Proportional Controller

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 of the error. A most widely used form of continuous control mode is the proportional control action, in which a …

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On Off Controller

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. When the measured variable is below the set point, the controller is ON and the output signal has maximum value. …

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Step Function Response

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 response to the step excitation is called the Process Reaction curve. Two typical process reaction curves are shown in Fig. …

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Basic Automatic Control

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, there are more than one input along with noise signals which are also present and there are more than one …

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Bolometer

Bolometer: Bolometric measurements are based on the dissipation of RF power in a small temperature sensitive resistive element, called a Bolometer. This bolometer may be a short ultra thin wire having a positive temperature coefficient (PTC) of resistance, called Baretter, or a bead of semi-conductor having a negative temperature coefficient (NTC) called Thermistor. Both Baretters …

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