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1. The symbol for “capillary line” in instrumentation diagram is 16. A frequency response measure on how well the system
response to variations in the output signal.
a) c) a) feedback c) control system
b) d) b) continuous time d) bandwidth
2. Pick out the symbol for “locally mounted instrument” in 17. The stimulus, excitation or command applied to control a
instrumentation diagram system, typically from an external energy source, usually to
produce a specified response from the control system.
a) process control c) input
a) b) c) d) b) set d) control system
3. Which is the symbol for “pneumatic control valve” 18. A sensor usually made of a semiconductor that utilizes the
effect of temperature on the resistance to current is a
a) thermocouple b) thermistor c) resistor d) capacitor
a) b) c) d) no answer 19. The proportional action repeat rate is known from this
4. Arrangement of physical components connected or related control parameter.
in such a manner as to command, direct or regulate itself or a) derivative time c) integral time
another system is a b) controller bias d) controller gain
a) stimulus c) control system 20. It is an external signal applied to the feedback control
b) unit process d) process control system usually at the first summing point, in order to
5. Ratio of the maximum controllable flow to the minimum command a specified action of the plant. It usually
controllable flow represents the desired plant output behavior.
a) rangeability c) zero-span ratio a) control signal c) feedback element
b) hysteresis d) installed flow characteristics b) reference input d) controlled output
6. Type of control mode which does not influence the final 21. A control structure with two feedback controllers with the
steady state value of the error, provides rapid correction output of the primary controller changing the set point of
based on the rate of change of the error. the secondary controller whose output goes to the final
a) proportional c) proportional-integral controller.
b) derivative d) integral a) feedforward control c) cascade control
7. Type of control mode which achieves zero offset and b) ratio control d) override control
adjusts the manipulated variable in a slower manner, thus 22. Closed loop poles of a stable second order system could be
giving poor dynamic performance and can cause instability if a) both real and positive
tuned improperly b) complex conjugate with positive real part
a) proportional c) proportional-integral c) both real and negative
b) derivative d) integral d) one real positive and the other real negative
8. Type of control mode which does not provide zero offset 23. The term analogous to the electrical current in a thermal
but reduces the error and speeds the dynamic response of system is the
the system, it may cause instability if tuned improperly. a) temperature difference c) heat flow rate
a) proportional c) proportional-integral b) heat content in the system d) no answer
b) derivative d) integral 24. The response of two tanks of same size and resistance in
9. The most commonly used control mode in the industry series is
a) proportional c) proportional-integral a) over damped c) under damped
b) derivative d) integral b) critically damped d) no answer
10. The simplest mode of control which is characteristic of a 25. A simple pitot tube measures
two position control commonly utilized in a thermostat for a) average velocity c) maximum velocity
controlling the temperature of heaters, air-conditioners, b) point velocity d) static pressure
refrigerators and etc. 26. Which of the following is a contact pyrometer?
a) proportional c) programmable logic control a) optical pyrometer c) radiation pyrometer
b) derivative d) on-off control b) infrared pyrometer d) resistance pyrometer
11. It is a control system in which the control action is 27. The amplitude ratio for the sinusoidal response of
independent of the output. _________ is less than 1
a) closed loop system c) feedback control system a) first order system c) transportation lag
b) open loop system d) feedforward control system b) second order system d) no answer
12. Actual response obtained from the control system. It may 28. Pressure of 0.0001 absolute psi can be measured by
or may not be equal to the specified response. a) Mcleod gauge c) Pirani gauge
a) input b) output c) answer d) result b) Thermocouple gauge d) Bourdon gauge
13. It is used to convert one signal or energy form into another. 29. The Bode stability criterion is applicable when
a) transducer b) amplifier c) detector d) resistor a) Gain and phase curves decrease continuously with
14. It establishes the functional relationship between the frequency
controlled output and the primary feedback signal b) Gain curve increases and the phase curve decreases
a) control signal c) measurement with frequency
b) reference input d) controlled output c) Gain curve and phase curve both increase with
15. Not a flow measuring device frequency
a) orifice meter c) magnetic flowmeter d) Gain curve decreases and the phase curve increase
b) turbine meter d) diaphragm meter with frequency
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30. Thermocouple is suitable for measuring 44. Which of the following controllers has maximum offset?
a) liquid temperatures only a) P-controller c) P-I controller
b) very high temperatures only b) P-D controller d) P-I-D controller
c) very low temperatures only 45. The roots of the characteristic equation of an under
d) both high and low temperatures damped second order system are
31. A barometer measures a) real, negative and equal c) real, negative &
a) atmospheric pressure c) dynamic pressure unequal
b) gauge pressure d) absolute pressure b) real, positive and unequal d) complex conjugates
32. Routh stability method uses 46. An inherent disadvantage of this control system is that
a) open loop transfer function c) either a or b it results in continuous cycling of the controlled variable
b) closed loop transfer function d) neither a nor and thus produces excessive wear in the final control
b element.
33. Bode stability method uses a) on-off control c) P-only control
a) open loop transfer function c) either a or b b) PI-only control d) PID control
b) closed loop transfer function d) neither a nor b 47. Which of the following flow-metering instruments is an
34. An unwanted signal that affects the system’s output area meter?
signal a) venturi meter c) rotameter
a) disturbance signal c) controlled variable signal b) pitot tube d) hot wire anemometer
b) error signal d) sensor signal 48. Conversion formula for converting amplitude ratio ( AR)
35. The device that causes the process to provide the into decibels is
output a) Decibel = log10 (AR) c) Decibel=20 log10 (AR)
a) sensor b) transmitter c) adaptor d) b) Decibel=20 log e(AR) d) Decibel=20 log10 (AR)0.5
actuator 49. Continuous measurement of moisture content of paper in
36. The time for the system to respond to a step input and paper industry is done by measuring
attain a response equal to the magnitude of the input. a) thermal conductivity through the paper
a) response time c) rise time b) electrical resistance through the paper
b) equalization time d) equilibrium time c) magnetic susceptibility
37. The system that uses a measurement of the output and d) both b and c
compares it with the desired output is control 50. Process degrees of freedom
system a) indicates the minimum number of controller to be
a) feed-forward c) closed-loop feedback used
b) adaptive d) inferential b) indicates the maximum number of controller to be
38. The amount the system output response proceeds used
beyond the desired response c) determines both maximum and minimum number of
a) offset b) offshoot c) gain d) controllers to be used
overshoot d) gives no idea of controllers
39. Output signal is fed back so that it adds to the input 51. Steady state deviation resulting from a change in the
signal value of the load variable is called
a) positive feedback c) comparator gain a) error ratio b) static ratio c) deviation d)
b) negative feedback d) forward feedback offset
40. A system that exhibits the desired performance in the 52. Which of the following is an undesirable dynamic
presence of significant plant uncertainty. characteristic of an instrument?
a) stable control c) automatic control a) reproducibility c) time lag
b) reliable control d) robust control b) dead zone d) static error
41. Pick out the first order system from among the 53. Load cells are used for the measurement of
following a) stress b) strain c) velocity d)
a) damped vibrator weight
b) mercury in glass thermometer kept in boiling water 54. Which of the following is the dynamic characteristics of
c) interacting system of two tanks in series an instrument?
d) non-interacting system of two tanks in series a) reproducibility c) sensitivity
42. A temperature sensor with the following advantages: no b) dead zone d) fidelity
physical contact, wide range and fast response and 55. In a single tank system, the transfer function of level to
measures small target or average value over large size inlet flow rate
a) thermocouple c) pyrometer a) R/TS b) R/(TS + 1) c) 1/(TS + 1) d)
b) thermistor d) RTDs 1/TS
43. Which of the following controllers has the least 56. A proportional controller with a gain of Kc is used to
maximum deviation? control a first order process. The offset will increase if
a) P-controller c) P-I controller a) Kc is reduced
b) P-D controller d) P-I-D controller b) Kc is increased
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c) integral control action is introduced respectively at these two temperatures. If the cold
d) derivative control action is introduced junction temperature is shifted from 00C and 300C, then
57. Response of a system to a sinusoidal input called the emf correction in mV is
a) impulse response c) unit step response a) 3.13 b) 2.92 c) 2.61 d) 2.02
b) frequency response d) step response 68. The characteristic equation for a system is s3 + 9s2 +
58. Flow measuring instruments with different 26s + 12 (2+ KC) = 0. Using the Routh test, the value of
specifications (zero and span) are available for an KC that will keep the system on the verge of instability is
application that flow rate measurements in the range of a) 20.9 b) 18.4 c) 17.5 d) 15.3
300 L/h to 400 L/h. The appropriate instrument for
this application is one whose specifications are
a) zero=175 L/h, span=150 L/h 69. The inverse Laplace transform of is
b) zero=175 L/h, span=200 L/h
c) zero=275 L/h, span=100 L/h
a) c)
d) zero=275 L/h, span=150 L/h
59. A first order system with unity gain and time constant b) d)
is subjected to a sinusoidal input of frequency = 1/. 70. A block diagram for a control system is shown below.
The amplitude ratio for this system is The steady state gain of the closed loop system,
1 between output Y(s) and set point R(s) is
a) 0.25 b) 0.5 c) 1 d)
√2
60. An amplitude ratio of 0.1 corresponds to ______
decibels
a) -10 b) -20 c) 10 d) 20
61. The transfer function of the first order system is
1 1 s
a) b) c)
τ s+ 1 τs τ s+ 1
s
d)
τs
62. What is the Laplace transform of sin t ? a) 5/9 b) 4/9 c) 1/3 d) 2/9
1 s 71. The characteristic equation of a closed loop system
a) 2 b) 2 c) using a proportional controller with gain KC is
s +1 s +1 12s3 + 19s2 + 8s + 1+ KC=0
1 s At the onset of instability, the value of KC is
2 d) 2 a) 35/3 b) 10 c) 25/3 d) 20/3
s −1 s −1
72. The block diagram of a system with a proportional
2s controller is shown below. A unit step input is
63. A system with a transfer function is
4 s+1 introduced in the set point. The value of KC to provide a
a) zero order c) 2nd order critically damped response for U=0, P=8 and m=1 is
b) 1 order
st
d) 3rd order a) 3.34 b) 2.58 c) 1.53 d) 1.12
64. Number of poles in a system with transfer function
1
s ²+ 2 s ²+1
a) 1 b) 2 c) 3 d) 5
65. The frequency response of a first order system has a
phase shift with lower and upper bounds given by
a) [ −∞ ,
π
2 ] b) [ −π
2
,0 ] c)
[ −π π
,
2 2 ] d) [ ]
0,
π
2 73. The transfer function, G(s), whose asymptotic Bode
66. A thermometer initially at 100 0C is dipped at t = 0 into diagram is shown below is
an oil bath, maintained at 150 0C. If the recorded
temperature is 1300C after 1 minute, then the time
constant of the thermometer in minutes is
a) 1.98 b) 1.35 c) 1.26 d) 1.09
67. A thermocouple having a linear relationship between 0 0C
and 3500C shows an emf of zero and 30.5 mV
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a) 10s + 1 b) 10s – 1 c) s – 10 d) s + 10
74. Consider the process as shown below. A constant head
pump transfers a liquid from a tank maintained at 20 psi
to a reactor operating at 100 psi, through a heat
exchanger and a control valve. At the design conditions,
the liquid flow rate is 1000 L/min, while the pressure
drop across the heat exchanger is 40 psi, and that
across the control valve is 20 psi. Assume that the
pressure drop across the heat exchanger varies as the
square of the flow rate. If the flow is reduced to 500
L/min, then the pressure drop across the control valve is
a) 30 psi b) 50 psi c) 80 psi d) 150 psi
75. The Laplace transform of the function shown below is
a) c)
b) d)
