Question: “A control system is unstable, if the open loop frequency response exhibits an amplitude ratio exceeding unity at the crossover frequency.” This is _______________ criterion?

• 1. Bode stability
• 2. Nyquist
• 3. Routh stability
• 4. None of these

Question: A typical example of a physical system with under damped characteristic is a____________________?

• 1. U-tube manometer
• 2. Spring loaded diaphragm valve
• 3. CSTR with first order reaction
• 4. Thermocouple kept immersed in a liquid filled thermowell

Question: In a closed loop system, the process to be controlled is an integrating process with transfer function 1/2s. The controller proposed to be used in an integral controller with transfer function 1/T1s. When a step change in set point is applied to such a cl

• 1. Overdamped response
• 2. Underdamped response
• 3. Undamped response
• 4. Unstable response

Question: Working principle of mercury in glass thermometer is__________________?

• 1. Volumetric expansion
• 2. Pressure rise with temperature
• 3. Linear expansion
• 4. None of these

Question: Which of the following filled system expansion thermometers has the lowest positive temperature measurement capability ?

• 1. Mercury in glass thermometer
• 2. Alcohol in glass thermometer
• 3. Fused metal (Na or K) in steel thermometer
• 4. Nitrogen in steel thermometer

Question: The root locus plot of the roots of the characteristics equation of a closed loop system having the open loop transfer function K (s + 1)/[2 (2s + 1) (3s + 1)] will have a definite number of loci for variation of K from 0 to ∞. The number of loci is______

• 1. 1
• 2. 2
• 3. 3
• 4. 4

Question: Water is entering a storage tank at a temperature T0 and flow rate Q0 and leaving at a flow rate Q and temperature T. There are negligible heat losses in the tank. The area of cross-section of the tank is A0. The model that describes the dynamic variation

• 1. Q0(T0 – T) = Ac . h (dT/dt)
• 2. Q0T0 – QT = Ac . h (dT/dt)
• 3. Q(T0 – T) = Ac . h (dT/dt)
• 4. Q(T0 – T) = Ac . (dTH/dt)

Question: The transfer function for a P-D controller is________________?

• 1. Kc(1+ηD s)
• 2. Kc(1 +1/ηD s)
• 3. Kc ηD s
• 4. Kc/ηD s

Question: 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________________?

• 1. 5π/12
• 2. π/6
• 3. π/12
• 4. π/3

Question: Dead zone is the__________________?

• 1. Same as time constant
• 2. Same as transportation lag
• 3. Maximum change in the variable that does not change the reading of the instrument
• 4. None of these