Process Control and Instrumentation Objective Questions and Answers

127. A first order system with a time constant of 1 min is subjected to frequency response analysis. At an input frequency of 1 radian/min, the phase shift is

128. Instrumentation in a plant offers the advantage of

A. Greater safety of operation

B. Better quality of product

C. Greater operation economy

D. All of the above

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129. The time constant of a unity gain, first order plus time delay process is 5 min. If the phase lag at a frequency of 0.2 rad/min is 60°, then the dead time (in minutes) is

A. $$\frac{{5\pi }}{{12}}$$

B. $$\frac{\pi }{6}$$

C. $$\frac{\pi }{{12}}$$

D. $$\frac{\pi }{3}$$

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130. If response of a control system is to be free of offset and oscillation, the most suitable controller is

A. Proportional controller

B. Proportional-derivative(PD)controller

C. Proportional-integral (PI) controller

D. Proportional integral-derivative (PID) controller

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131. Concentration of sugar solution can be determined by the