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GATE 2021 BT – Question 23

Fundamentals of Biological Engineering · Process Control: Measurement devices, valves, first and second order systems, feedback and feed forward control, P, I and D controllers and tuning · 1 mark · Multiple choice

A feedback loop controls tank liquid level h by inlet valve V. $F_1,F_2$ are inlet and outlet flows, LT is transmitter, LC is controller, $h_{sp}$ is set point, $h_m$ measured level and $P_v$ valve pressure. The manipulating variable(s) is/are

source diagram and its labels are reproduced in the attached image.
  1. $F_1$ only
  2. $F_2$ only
  3. $h_m,P_v$ only
  4. $h_{sp},P_v$ only

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Show answer and explanation

Correct answer: (A) $F_1$ only

Explanation

The valve changes inlet flow F1. Outlet flow is a disturbance and measured level is feedback rather than an independently manipulated variable.