Multiple Choice Questions and Answers on Process Control and Instrumentation 1. The temperature of tempering oil baths maintained at 400°C during heat treatment of steel is measured by a/an __________ thermocouple. a) chromel-alumel b) iron-constantan c) platinum-platinum/rhodium d) none of these. Answer: iron-constantan 2. Flapper nozzle is used in a/an __________ controller. a) electronic b) hydraulic c) pneumatic d) none of these Answer: pneumatic 3. The __________ of a vapor pressure thermometer is a functioning element. a) pointer b) bourdon tube c) bulb d) none of these Answer: pointer 4. A negative gain margin expressed in decibels means a/an __________ system. a) stable b) unstable c) critically damped d) none of these Answer: unstable 5. Temperature measuring instruments are standardised mostly with __________ points of pure substances. a) melting b) boiling c) both (a) & (b) c) neither (a) nor (b) Answer: both (a) & (b) 6. Response of a system to a sinusoidal input ...

Multiple Choice Questions and Answers on Inverse Systems and Deconvolution 1. If the frequency response of an FIR system is given as H(z)=1-z-1-6z-2, then the system is ___________ a) Minimum phase b) Maximum phase c) Mixed phase d) None of the mentioned Answer: Maximum phase 2. An IIR system with system function H(z)=B(z)A(z) is called a minimum phase if ___________ a) All poles and zeros are inside the unit circle b) All zeros are outside the unit circle c) All poles are outside the unit circle d) All poles and zeros are outside the unit circle Answer: All poles and zeros are inside the unit circle 3. If the frequency response of an FIR system is given as H(z)=6+z-1-z-2, then the system is ___________ a) Minimum phase b) Maximum phase c) Mixed phase d) None of the mentioned Answer: Minimum phase 4. If the frequency response of an FIR system is given as H(z)=1-5/2z-1-3/2z-2, then the system is ___________ a) Minimum phase b) Maximum phase c) Mixed phase d) N...

Multiple Choice Questions and Answers on Tuning of PID Controllers 1. Lag-lead compensation is a: a) Increases bandwidth b) Attenuation c) Increases damping factor d) Second order Answer: Second order 2. Derivative error compensation: a) Improvement in transient response b) Reduction in steady state error c) Reduction is settling time d) Increase in damping constant Answer: Increase in damping constant 3. Lag compensation leads to: a) Increases bandwidth b) Attenuation c) Increases damping factor d) Second order Answer: Attenuation 4. Derivative output compensation: a) Improvement in transient response b) Reduction in steady state error c) Reduction is settling time d) Increase in damping constant Answer: Reduction is settling time 5. Phase lag controller: a) Improvement in transient response b) Reduction in steady state error c) Reduction is settling time d) Increase in damping constant Answer: Reduction in steady state error 6. Rate compensation : a) Increases bandwidth b) Attenuatio...

Multiple Choice Questions and Answers on Integral Square Error 1. The response of a servomechanism is 1+0.2e-60t-1.2e-10t when subjected to a unit step input. What is the damping ratio? a) 1.21 b) 1.43 c) 1.59 d) 1.74 Answer: 1.43 2. For a unity feedback control system, the open loop transfer function G(s) = 10(s+2)/s2(s+1). What is the acceleration error constant? a) Infinity b) 5 c) 10 d) 20 Answer: 20 3. The open loop transfer function for a unit feedback system is G(s) = K/s(sT+1). By what factor the amplitude gain K should be reduced so that the peak overshoot becomes 25% from 75%? a) 75 b) 25 c) 20 d) 10 Answer: 20 4. How many types of controllers and compensators are there respectively? a) 4, 3 b) 3, 4 c) 4, 5 d) 5, 4 Answer: 4, 3 5. A unity feedback system has an open loop transfer function G(s) =25/s(s+8). What is the percentage of it’s peak overshoot? a) 0.13% b) 1.13% c) 1.26% d) 1.52% Answer: 1.52% 6. What is the response of the feedback function with open loop transfer fun...

Multiple Choice Questions and Answers on Advanced Control system 1. Vector images are __________ a) Composed of pixels b) Composed of thousands of dots c) Slightly more difficult to manipulate than other images d) Composed of objects such as lines, rectangles, and ovals Answer: Composed of objects such as lines, rectangles, and ovals 2. Images made up of thousands of pixels are called ___________ a) Bitmap b) Vector c) Story boards d) Graphics Answer: Bitmap 3. CorelDraw is an example of a(n) __________ a) Groupware application b) Bit publishing package c) Paint program d) Graphics suite Answer: Graphics suite 4. Programs used to create or modify vector images are called __________ a) Illustration programs b) Image editors c) Graphical modifiers d) Bit publishing packages Answer: Illustration programs 5. Programs used to create or modify bitmap images are called __________ a) Illustration programs b) Paint programs c) Graphical modifiers d) Bit publishing packages Answer: Paint program...

Multiple Choice Questions and Answers on Transfer Functions 1. A linear system at rest is subject to an input signal r(t)=1-e-t. The response of the system for t>0 is given by c(t)=1-e-2t. The transfer function of the system is: a) (s+2)/(s+1) b) (s+1)/(s+2) c) 2(s+1)/(s+2) d) (s+1)/2(s+2) Answer: 2(s+1)/(s+2) 2. A control system whose step response is -0.5(1+e-2t) is cascaded to another control block whose impulse response is e-t. What is the transfer function of the cascaded combination? a) 1/(s+2)(s+1) b) 1/(s+1)s c) 1/(s+3) d) 0.5/(s+1)(s+2) Answer: 1/(s+2)(s+1) 3. In regenerating the feedback, the transfer function is given by a) C(s)/R(s)=G(s)/1+G(s)H(s) b) C(s)/R(s)=G(s)H(s)/1-G(s)H(s) c) C(s)/R(s)=G(s)/1+G(s)H(s) d) C(s)/R(s)=G(s)/1-G(s)H(s) Answer: C(s)/R(s)=G(s)/1-G(s)H(s) 4. A transfer function has two zeroes at infinity. Then the relation between the numerator(N) and the denominator degree(M) of the transfer function is: a) N=M+2 b) N=M-2 c) N=M+1 d) N=M-1 Answer: N=M-2 ...

Multiple Choice Questions and Answers on Process Dynamics and Control 1. A non-linear system will have __________ steady state values. a) One b) More than one c) Two    d) Three Answer: More than one 2. Bode stability method uses __________ loop transfer function. a) Open b) Closed c) Either a or b d) Neither a nor b Answer: Open 3. A negative gain margin expressed in decibels means a/an __________ system. a) Stable b) Unstable c) Critically damped d) None of these Answer: Unstable 4. Strain gage pressure transducers are used to measure __________ pressures. a) Gage as well as vacuum b) Absolute as well as differential c) Both a & b d) Neither a nor b Answer: Both a & b 5. __________ controller has the maximum stabilising time. a) P b) PD c) PI d) PID Answer: PI 6. A control system is unstable, if the open loop frequency response exhibits an amplitude ratio exceeding unity at the crossover frequency. This is __________ criterion. a) Bode stability b) Nyquist c) Routh s...

  Process Control Multiple Choice Questions 1. Which of the following parameters is not useful in the construction of pressure bellows? a) Hysteresis b) Sensitive to changing pressures c) Corrosion d) pH Answer: pH 2. Who invented the Bourdon tube? a) Eugene b) Howe c) Flynn d) Royce Answer: Eugene 3. Which of the following is a desirable characteristic of an instrument ? a) High fidelity b) High drift c) Poor reproducibility d) High measuring lag Answer: High fidelity 4. Thermistor, which has high temperature co-efficient of resistivity, is used as the sensing element in resistance thermometer. It is a/an a) insulator b) conductor c) solid semi-conductor d) liquid semi-conductor Answer: solid semi-conductor 5. Which of the following temperature measuring instruments need not touch the object whose temperature is being measured ? a) Thermo electric pyrometer b) Mercury in glass thermometer c) Filled system thermometer d) Radiation/infrared pyrometer Answer: Radiation/infrared pyrom...

  Temperature Measurement Multiple Choice Questions 1. Reference junction compensation is necessary in thermocouple-based temperature instruments because ___________  a) Copper extension wire has a tendency to corrode b) Thermocouples are inherently nonlinear c) The reference junction generates a temperature-dependent voltage d) The junction’s electrical resistance varies with temperature Answer: The reference junction generates a temperature-dependent voltage 2. Which of the following is made up of mixtures of pure oxides of iron and nickel? a) Thermistors b) Mercury thermometers c) Radiation thermometers d) Metallic thermometers Answer: Thermistors 3. The heat control at large-scale in the fermenter is carried out by _________ a) Inter heating coils b) Heating jacket c) Controlled bath d) Cold-water circulation Answer: Cold-water circulation 4. The negative lead of a thermocouple is always colored a) Blue b) Yellow c) Red d) White Answer: Red 5. The resistance _________ with...

  Level Measurement Multiple Choice Questions 1. Which of the following devices are used for a level to force conversion? a) Load cell b) Membrane c) Diaphragm d) Voltmeter Answer: Load cell 2. If the specific gravity of the liquid inside the vessel increases, what aspects of the transmitter’s calibration will we need to change in order to maintain accurate liquid level measurement? a) We will need to change the transmitter’s LRV and linearity b) We will need to change the transmitter’s linearity and span c) We will need to change the transmitter’s LRV and URV d) We will need to change the transmitter’s linearity and zero Answer : We will need to change the transmitter’s LRV and URV 3. Suppose a storage vessel holds a liquid of unpredictable density. Identify which level measurement technology will not maintain accurate measurement of liquid height in the vessel as the liquid density changes a) Differential pressure transmitter b) Guided-wave radar c) Ultrasonic d) Float and tape A...

  Flow Measurement Objective Type Questions and Answers 1. For accurate operation, orifice plate flowmeters require a) Laminar flow b) Fully-developed turbulent flow c) Swirls and eddies in the flow stream d) Transitional flow Answer : Fully-developed turbulent flow 2. A flag flapping in the breeze illustrates what type of dynamic fluid effect? a) Cavitation b) Vortex shedding c) Transitional flow d) Coriolis effect Answer : Vortex shedding 3. A ∆P transmitter calibrated for a range of 0 to 100 ”H2O measures liquid flow through an orifice plate from 0 to 1200 GPH. Calculate the new calibration range for the transmitter if we desire to decrease the flow measurement range to 0 to 700 GPH, using the same orifice plate. a) 0 to 34.03” H2O b) 0 to 76.38” H2O c) 0 to 171.4” H2O d) 0 to 293.9” H2O Answer : 0 to 34.03” H2O 4. Identify which of the following flowmeters inherently measures mass flow rate a) Thermal b) Magnetic c) Flow nozzle d) Vortex Answer : Thermal 5. As an incompressible...

  Pressure Regulators Multiple Choice Questions 1. The measuring element _______________ a) Measures the inlet flow b) Measures the outlet flow c) Compares the inlet flow to the outlet flow d) None of the above Answer: Compares the inlet flow to the outlet flow 2. A pressure regulator includes? a) restricting element b) loading element c) measuring element d) All of the above Answer: All of the above 3. Regulators are used for? a) Gases b) Liquid c) Solid d) Both a and b Answer: Both a and b 4. _____________ regulators are two regulators in series in the same housing that operate to reduce the pressure progressively in two steps instead of one. a) One stage b) Two stage c) Three stage d) Four stage Answer: Two stage 5. Restricting element in a pressure regulator can be _________ a) Globe valve b) Poppet valve c) Butterfly valve d) All of the above Answer: All of the above 6. In pressure regulators load flow is ___________ proportional to regulator flow a) depends b) indirectly...

  Control Loops Multiple Choice Questions 1. The most common analog signal standard for industrial process instruments is 4 to 20 _________ a) milliamps DC b) amps AC c) volts d) milliamps Answer: milliamps DC 2. Which of the following is not a “final control element”? a) A pressure transmitter b) An electric motor c) A heating element d) A control valve Answer : A pressure transmitter 3. Identify which of the following is an example of a “primary sensing element”  a) I/P transducer b) Instrument signal cable c) Control valve d) Diaphragm Answer : Diaphragm 4. A basic control loop will consist of __________ a) signal converter, resistor, knob, and control valve b) transducer, valve packing, hex-head wrench, and tubing c) transmitter, controller, I/P transducer, and control valve d) resistor, capacitor, terminal block, and battery Answer : transmitter, controller, I/P transducer, and control valve 6. The purpose of a “shield” wire on an instrument signal cable is to __________ ...

  Dynamic behaviour of first order and second order systems Objective Questions and Answers 1. In a second order system, the damping factor is 0.65 and the natural frequency is 4 Hz. If the stiffness of springs is halved, the new values of damping factor and natural frequency are _______ a) 0.92, 2.83 Hz b) 0.46, 5.66 Hz c) 0 92, 5.66 Hz d) 0.46, 2.83 Hz. Answer: 0.92, 2.83 Hz 2. The volume of bulb of a liquid filled thermometer is 1000 mm3. Its time constant and sensitivity are respectively 300 s and 3.6 mm/°C. If the volume of the bulb is reduced to 500 mm3, the sensitivity becomes ______________ a) 7.2 mm/°C b) 10.8 mm/°C c) 1.8 mm/°C d) 1.2 mm/°C if other conditions remain the same. Answer: 1.8 mm/°C 3. In force-current analogy stiffness constant K is analogous to __________ a) inductance b) reciprocal of inductance c) capacitance d) reciprocal of capacitance Answer: reciprocal of inductance 4. Dynamic response consists of __________ a) two parts, one steady state and the other...