Instrumentation and process control quiz 2015

INSTRUMENTATIONS AND PROCESS CONTROL QUIZ

Q. 1 Consider a control system with the open loop transfer function given by:

In the above function, pre-factor of s is in minutes and K_c is the gain of proportional controller. The frequency for phase margin of 30 ⁰ is 4.04rad/min. The value of K₀ for a gain margin of 1.7 (up to one decimal place ) is.....

Q. 2.The transfer function for the disturbance response in an open-loop process is given by G_d ^open (s). The corresponding transfer function for the disturbance response in a closedloop feedback control system with proportional controller is given by G_d ^closed (s).Select the option that is ALWAYS correct {O[G(s)] represents order of transfer function G(s)}:

o[G_d ^open (s)] = o[G_d ^closed (s)]
o[G_d ^open (s)] ≠ o[G_d ^closed (s)]
o[G_d ^open (s)] ≥ o[G_d ^closed (s)]
o[G_d ^open (s)] ≤ o[G_d ^closed (s)]

Q. 3 Match the output signals as obtained from four measuring devices in response to a unit step change in the input signal

P. Gas chromatograph, with a long capacity tube
Q: Venturi tube
R: Thermocouple with first order dynamics
S: Pressure transducer with second order dynamics

P-IV, Q-III, R-II, S-I
P-III, Q-I, R-II, S-IV
P-IV, Q-I, R-II, S-III
P-II, Q-IV, R-III, S-I

Q. 4 Which one of the following transfer functions, upto a unit step change in disturbance at t =0 will show a stable time domain response with a negative initial slope (i.e, slope at t =0):

Q. 5 The block diagram for a process with feedback control for output deviation variable h is shown in the figure below. All transfer function are given with pre-factor of s in minutes. A unit step change is made in the set-point at t=0. The time required for h to reach 50% of its ultimate value, in minutes (up to two decimal places), is.....