[Download pdf] Top 20 PLC MCQ – Part -3

plc and scada mcq

Hi All, In this series I explained top 20 objective questions and answer. For more questions of PLC and SCADA MCQ series. Please checkout my all MCQ series on PLC and SCADA. I have created MCQ series on Basic Electronics, Power Electronics, 8051 Microcontroller, 8086 Microprocessor.

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If you are going to attempt any competitive exam then check your skills here. This is mock test questions which is asked in previous year paper in UPPCL, RSEB, Metro rail corporation and SSC JE.

Question 1 Which of the following statements about RLL is NOT true?

Answer : The right power rail is positive or the high side of the source, and the left power rail is the power return or ground.

Question 2 _____ is a method of entering ladder logic representation.

Answer : Boolean mnemonics

Question 3 When a relay is NOT energized

Answer : There is an electrical path through the NC contacts

Question 4 In a current sinking DC input module _____

Answer : The current flows out of the input field device.

Question 5 How is the speed of operation of conventional relay system as compared to digital controllers?

Answer : Very slow.

Question 6 The type of memory which is fast and temporarily stores the data which are immediately required for use is called as______.

Answer : RAM.

Question 7 _____ of PLCs can be done in very little time.

Answer : All of the above

Question 8 How is the noise immunity of PLCs to electrical noises as compared to that of conventional relay controllers?

Answer : Poor

Question 9 _____ of PLCs can be done in very little time

Answer : All of the above

Question 10 Which of the following statements is correct?

Answer : The number of ladder logic virtual relays and input and output instructions is limited only by memory size.

Question 11 PLC can be _____ in plant to change the sequence of operation.

Answer : Programmed and reprogrammed.

Question 12 The PLC is used in _______.

Answer : All of the above.

Question 13 Which of the following can be the output of PLC?

  1. Relay coils
  2. Solenoids
  3. Indicators
  4. Motors
  5. Lamps
  6. Alarms

Select correct option

Answer : All the (1), (2), (3), (4), (5), and (6)

Question14 Instructions available in PLCs can be grouped in two categories: ________and ________ instructions.

Answer : basic ladder _ enhanced ladder

Question15 What one item in the output module circuit above should be changed to make it correct.

Answer : Current flow direction

Question 16 Which of the following cannot be an input that is given to the PLC?

Answer : None of the above

Question 17 An AND function implemented in ladder logic uses

Answer : Normally-open contacts in series

Question 18 Ladder contacts can be programmed in

Answer : a and b both true

Question 19 PLC instructions ___________.

Answer : Were added to the original relay instructions to make PLCs more powerful.

Question 20 The L2 rail side of an electromechanical circuit is represented by _____________.

Answer : The right side of the ladder rung.