Programmable Logic Controller 1. The acronym PLC stands for a) Pressure Load Control b) Programmable Logic Controller c) Pneumatic Logic Capstan d) PID Loop Controller Answer: Programmable Logic Controller 2. In PLC programming, a retentive function is one that a) Defaults to the “on” state b) Is not reset after a power cycle c) Defaults to the “off” state d) Cannot be edited or deleted Answer: Is not reset after a power cycle 3. A good application for a timed interrupt in a PLC program would be a) A communications function block b) A PID function block c) A math function block d) A motor start/stop rung Answer: A PID function block 4. In a PLC, the scan time refers to the amount of time in which   a) the technician enters the program b) timers and counters are indexed by c) one “rung” of ladder logic takes to complete d) the entire program takes to execute Answer: the entire program takes to execute 5. The difference between online and offline PLC programming is a) whether the PLC i

  live & dead zero 1. What is ‘live zero’? a) Output zero for zero input b) Output non zero for zero input c) Output null for all input d) Output unpredictable Answer: Output non zero for zero input Dead zone is the a) Same as time constant b) Same as transportation lag c) Maximum change in the variable that does not change the reading of the instrument d)  None of these Answer: Maximum change in the variable that does not change the reading of the instrument

Pressure Measurement   1. Another word for “pressure” is a) pH b) Head c) Density d) Force Answer : Head 2. If a force of 3400 pounds is applied to a circular piston 2 inches in diameter, calculate the fluid pressure working against the piston. a) 344.5 PSI b) 270.6 PSI c) 850 PSI d) 1082.3 PSI Answer : 1082.3 PSI 3. Which of the following is not a type of pressure sensing element? a) Bellows b) Bourdon tube c) Manometer d) Orifice plate Answer : Orifice plate 4. If the pressure applied to the “low” side of a ∆P transmitter increases while the pressure applied to the “high” side remains steady, the transmitter output should a) Fail low b) Remain the same c) Increase d) Decrease Answer : Decrease 5. Convert a pressure measurement of 20 PSIA into units of inches water column (gauge) a) 1321” H2O b) 510.1” H2O c) 701.2” H2O d) 146.7” H2O Answer : 146.7” H2O 6. Identify the proper sequence of valve actions for a three-valve manifold and bleed when taking a differen

  Two Wire Transmitters 1. The remote mounting feature of two-wire transmitter near the sensor reduces the effects of _________ a) Noise b) Signal Degradation c) Both a & b d) None of the above Answer: Both a & b 2. Why is an ac power not required in the remote areas or locations for operation purpose of two-wire transmitter? a) transmission power is lowered upto 4-20mA current output signal b) transmission power is lowered upto 1-4 mA current output signal c) transmission power is lowered upto 1-10 mA current output signal d) two-wire transmitters do not operate in remote areas Answer: transmission power is lowered upto 4-20mA current output signal 3. How does the appearance of any noise rather than the electrical noise that intrude in the current output signal of two-wire transmitter get eliminated ? a) by common-mode rejection of transmitting device b) by common-mode rejection of interfacing device c) by common-mode rejection of receiving device d) none of the above Answer:

  Pneumatic Signal , Pneumatic Systems, Pneumatic Control Mechanisms Questions and Answers Pneumatic Signal  1. The standard range for pneumatically transmitted signals is a) 3-15 psig b) 5-20 psig c) 1-10 psig d) 4-20 psig Answer: 3-15 psig  2.  pneumatic signal are the signals produced by changing the air pressure in the signal pipe in proportion to the measured change in a process variable.  a) True b) False Answer: True Pneumatic Systems 1. Hydraulic and pneumatic circuits a) Perform the same way for all functions b) Perform differently for all functions c) Perform the same with some exceptions d) Does not perform all the functions Answer: Perform the same with some exceptions 2. Fluid power circuits use schematic drawings to a) Simplify component function details b) Make it so only trained persons can understand the functions c) Make the drawing look impressive d) Make untrained person to understand Answer: Simplify component function details 3. The most common hydraulic fluid is

  Transmitters Multiple Choice Questions Transmitters 1. AVC stands for ________ a) Abrupt Voltage Control b) Audio Voltage Control c) Automatic Volume Control d) Automatic Voltage Control Answer: Automatic Volume Control 2. In TV transmission, sound signal is ________ modulated. a) Phase b) Pulse c) Frequency d) Amplitude Answer: Frequency 3. Ring Modulator is ________ a) used for DSB-SC generation b) used for SSB-SC generation c) used for VSB generation d) used for AM generation Answer: used for DSB-SC generation 4. What is Carrier swing? a) Frequency deviation b) Width of sideband c) Instantaneous frequency d) Total variation in frequency Answer: Total variation in frequency 5. What is the role of the transmitter in the communication system? a) to decode a signal to be transmitted b) to convert one form of energy into other c) to detect and amplify information signal from the carrier d) to produce radio waves to transmit data Answer: to produce radio waves to transmit data 6. What i

  Flow Meter Questions and Answers 1. What are the major three methods of flow meters? Area flow meter Mass flow meter Quantity meters 2. List some examples of the inferential flow meter. In the inferential type of flow metering techniques, the out quantity flow rate is inferred from a characteristic effect of a related phenomenon. Turbine flow meters Target flow meters Ultrasonic flow meters 3. What are the different types of positive displacement meters? Reciprocating piston type Rotating vane type Nutating disk type Lobed impellar type Oscillating piston type 4. What are the different types of thermal flow meters? Heat transfer flow meters Hot wire flow meters 5. Name the different types of weighing methods  Semiconductor feed belt weighing ( Batch weighing) Continuous conveyor scale radio active transmission gauge volumetric solid methods 6. Write any two points of calibration of flow meter Wet meter – manometer which is calibrated with mercury Dry meter – manometer which is cali

  Process Control System 1. What is a process control system? a) system to keep the parameters at zero value b) system to maintain the parameters constant c) system to keep the parameters at highest value d) system to check the voltage Answer: System to maintain the parameters constant 2. A transducer converts ________ a) mechanical quantity to electrical form b) electrical quantity to physical form c) physical quantity to electrical form d) chemical quantity to physical form Answer: physical quantity to electrical form 3. What is the main objective of process control? a) to control physical parameters b) to control mechanical parameters c) to control optical parameters d) to control electrical parameters Answer: To control physical parameters 4. Physical parameters change due to ______ a) voltage b) current c) internal and external disturbances d) power Answer: internal and external disturbances 5. A process control system consists of _____ a) 10 elements b) 6 elements c) 2 elements d

  Transfer Function 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. In continuous data systems : a) Data may be continuous function of time at all points in the system b) Data is necessarily a continuous function of time at all points in the system c) Data is continuous at the inputs and output parts of the system but not necessarily during intermediate processing of the data d) Only the reference signal is continuous function of time Answer: Data is necessarily a continuous function of time at all points in the system 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 control system w

  Z transform 1. What is the set of all values of z for which X(z) attains a finite value? a) Radius of convergence b) Radius of divergence c) Feasible solution d) None of the mentioned Answer: Radius of convergence 2. Is the discrete time LTI system with impulse response h(n)=a n (n) (|a| < 1) BIBO stable? a) True b) False Answer: True 3. What is the ROC of a causal infinite length sequence? a) |z|<r 1 b) |z|>r 1 c) r 2 <|z|<r 1 d) None of the mentioned Answer: |z|>r 1 4. The Z-Transform X(z) of a discrete time signal x(n) is defined as ____________ a)   ∑ ∞ k=-∞   x(n)z n b)   ∑ ∞ k=-∞   x(n)z -n c)   ∑ ∞ k=0 x(n)z n d) None of the mentioned Answer:   ∑ ∞ k=-∞   x(n)z -n 5. What is the z-transform of the following finite duration signal? x(n)={2, 4, 5, 7, 0, 1}?                    ↑ a) 2 + 4z + 5z 2  + 7z 3  + z 4 b) 2 + 4z + 5z 2  + 7z 3  + z 5 c) 2 + 4z -1  + 5z -2  + 7z -3  + z -5 d) 2z 2  + 4z + 5 +7z -1  + z -3 Answer: 2z 2  + 4z +

  Discrete Time Systems 1. Comment on the causality of the following discrete time system: y[n] = x[-n]. a) Causal b) Non causal c) Both Casual and Non casual d) None of the mentioned Answer: Non causal 2. Is the function y[n] = cos(x[n]) periodic or not? a) True b) False Answer: True 3. Consider the system y[n] = 2x[n] + 5. Is the function linear? a) Yes b) No Answer: No 4. If n tends to infinity, is the accumulator function an unstable one? a) The function is marginally stable b) The function is unstable c) The function is stable d) None of the mentioned Answer: The function is unstable 5. Comment on the causality of the discrete time system: y[n] = x[n+3]. a) Causal b) Non Causal c) Anti Causal d) None of the mentioned Answer: Anti Causal 6.Comment on the time invariance of the following discrete system: y[n] = x[2n+4]. a) Time invariant b) Time variant c) Both Time variant and Time invariant d) None of the mentioned Answer: Time variant 7. How is a

Linear convolution  Read more 1 .Which of the following is a correct expression for Impulse response? A) x[n] = ∑ ∞ k=-∞  x[k]δ[n-k] B) x[n] = ∑ ∞ k=-∞  x[k]δ[nk] C) x[n] = ∑ ∞ k=-∞  x[k]δ[k] D) x[n] = ∑ ∞ k=-∞  x[k]δ[n] Answer:  x[n] = ∑ ∞ k=-∞  x[k]δ[n-k] 2.  The convolution sum is given by _____ equation. A) x[n]*h[n] = ∑ ∞ k=-∞  x[k]h[n-k] B) x[n]*h[n] = ∑ ∞ k=-∞  x[n]h[n-k] C) x[n]*h[n] = ∑ ∞ k=-∞  x[k]h[nk] D) x[n]*h[n] = ∑ ∞ k=-∞  x[k]h[k] Answer:  x[n]*h[n] = ∑ ∞ k=-∞  x[k]h[n-k]. 3. Impulse response is the output of ______ system due to impulse input applied at time=0? A) Linear B) Time varying C) Time invariant D) Linear and time invariant Answer: Linear and time invariant 4. Which of the following is correct regarding to impulse signal? A) x[n]δ[n] = x[0]δ[n] B) x[n]δ[n] = δ[n] C) x[n]δ[n] = x[n] D) x[n]δ[n] = x[0] Answer: x[n]δ[n] = x[0]δ[n] 5. Weighted superposition of time-shifted impulse responses is termed as _______ for discrete-time signals. A) Convoluti

  Causality And Stability Of Discrete Time Systems Discrete Time Systems Discrete time systems A discrete-time system is a system that maps an input sequence with an output sequence  y[n] = T {x[n]} A discrete-time system is a device or algorithm that, according to some well-defined rule, operates on a discrete-time signal called the input signal or excitation to produce another discrete-time signal called the output signal or response. Mathematically speaking, a system is also a function. The input signal x[n] is transformed by the system into a signal y[n], which we express mathematically as y[·] = T {x[·]} or y[n] = T {x[·]}[n] or x[·]  T→ y[·]  The notation y[n] = T {x[n]} is mathematically vague. The reader must understand that in general y[n] is a function of the entire sequence {x[n]}, not just the single time point x[n]. Input Signal x[n]→ Discrete-time system → Output Signal y[n] Causality If a discrete-time system is causal, then the current output sample depends only on the