PLC EFC CHENNAI NOV BATCH1 DATED 19th DEC 2024 - MSME

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PLC-EFC CHENNAI -19th DECEMBER 2024

1 / 50

One of the following has tendency to oscillate

Open loop system

Closed loop system

Both (a) and (b)

Neithe (a) nor (b)

2 / 50

A good application for a timed interrupt in a PLC program would be:

A communications function block

A PID function block

A math function block

A motor start/stop rung

A “watchdog” timer

3 / 50

In open loop system

The control action depends on the size of the system

The control action depends on system variables

The control action depends on the input signal

The control action is independent of the output

4 / 50

Which of the following statements about RLL is NOT true ?

NO contact symbol has two parallel lines to indicate an open contact.

RLL stands for Relay Ladder Logic.

NC contact symbol has the same two parallel lines with a line across them to indicate closed contacts.

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

5 / 50

An OR function implemented in ladder logic uses:

Normally-closed contacts in series

Normally-open contacts in series

A single normally-closed contact

Normally-open contacts in parallel

Normally-closed contacts in parallel

6 / 50

The ………………………………….. is moved toward the relay electromagnet when the relay is on.

Armature

Coil

NO contact

NC contact

7 / 50

When ___________ contacts are actuated, they disrupt the power supply through them.

normally open type

normally closed type

normally open and closed type

none of the mentioned

8 / 50

A switch whose operation is activated by an electromagnet is called

solenoid

relay

Indicator

sensor

9 / 50

Which is the type and styles of switches?

Locking and nonlocking

Normally open and normally closed

Single pole and multiple pole

All of the mentioned

10 / 50

Which of the following is an open loop control system ?

Field controlled D.C. motor

Ward leonard control

Metadyne

Stroboscope

11 / 50

A good application for a timed interrupt in a PLC program would be:

A communications function block

A PID function block

A math function block

A motor start/stop rung

A “watchdog” timer

12 / 50

In a Current sinking DC input module……………………………..

The Current flows out of the input field device

Requires that a AC sources be used with mechanical switches

The current flows out of the input module

Currents can flow in either direction at the input module

13 / 50

A good control system has all the following features except

Good stability

Slow response

Good accuracy

Sufficient power handling capacity

14 / 50

When a relay is NOT energized:

There is an electrical path through the NO contacts

There is an electrical path through the NC contacts

Neither the NO or the NC contacts have an electrical path

Both the NO and the NC contacts have an electrical path.

15 / 50

Which of the following RLL applications is not normally perfomed in early automation systems ?

On/Off control of field devices

Logical control of discrete devices.

On/Off control of motor starters

Proportional control of field devices.

16 / 50

AC output field devices can interface to

AC output modules

Relay output modules

Both a and b

Neither a or b

17 / 50

In closed loop control system, with positive value of feedback gain the overall gain of the system will

decrease

increase

18 / 50

In a Current sinking DC input module………………………………

The current flows out of the input field device

Requires that a AC sources be used with mechanical switches

The current flows out of the input module

Currents can flow in either direction at the input module

19 / 50

The difference between online and offline PLC programming is . . .

whether the PLC is running or stopped

whether the programming PC has internet connectivity

the type of programming cable used

where the edited program resides

the type of programmer used

20 / 50

Which one of the following increases the steady state accuracy.

Integrator

Differentiaor

Phase lead compensator

Phase lag compensator

21 / 50

Eddy current drive can be a retrofit for ____________

Constant speed system requirement

Variable speed system requirement

Dual speed system requirement only

None of the above

22 / 50

Control system with excessive noise, is likely to suffer from

Saturation in amplifying stages

Loss of gain

Vibrations

Oscillations

23 / 50

To increase the number of inputs and outputs of the PLC, one can use expansion modules.

True

False

24 / 50

A good application for a timed interrupt in a PLC program would be:

A communications function block

A PID function block

A math function block

A motor start/stop rung

A “watchdog” timer

25 / 50

AC servomotor resembles

Two phase induction motor

Three phase induction motor

26 / 50

Which of the following statements about a single pole double throw relay is true ?

Insulactus are used in the armature to isolate the electric switching contacts from the rest of the relay components

The NC contact and the pole ae in contact when the relay is off.

It has just one coil.

All of the above.

27 / 50

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

Very slow

Very fast

Same

Almost similar

28 / 50

As a result of introduction of negative feedback which of the following will not decrease ?

Band width

Overall gain

Distortion

Instability

29 / 50

Ladder logic programming consists primarily of:

Virtual relay contacts and coils

Logic gate symbols with connecting lines

Function blocks with connecting lines

Text-based code

Hieroglyphics

30 / 50

Which of the following is the output of a thermocouple ?

Alteranting current

Direct current

A.C. voltage

D.C. voltage

None of the above

31 / 50

fg
• decreases by the same amount as the gain increase
• increase by the same amount as the gain decrease
The transient response, with feedback system,

Rises slowly

Rises quickly

Decays slowly

Decays quickly

32 / 50

The acronym PLC stands for:

Pressure Load Control

Programmable Logic Controller

Pneumatic Logic Capstan

PID Loop Controller

Pressure Loss Chamber

33 / 50

Current flows into the………………………………..

Input terminal of a sinking DC input module

Input terminal of a sinking output field device

Output terminal of a sinking input field device

All of the above

34 / 50

The acronym PLC stands for:

Pressure Load Control

Programmable Logic Controller

Pneumatic Logic Capstan

Pressure Loss Chamber

35 / 50

In PLC, a digital counter consists of

a count register

an accumulator

a relay contact

all of the mentioned

36 / 50

In a PLC, the scan time refers to the amount of time in which …..

the technician enters the program

timers and counters are indexed by

one “rung” of ladder logic takes to complete

the entire program takes to execute

transmitted data communications must finish

37 / 50

In an automatic control system which of the following elements is not used ?

Error detector

Final control element

Sensor

Oscillator

38 / 50

The PLC was invented by.

Bill Gates

Dick Morley

Bill Landis

Tod Cunningham

39 / 50

Peripherals are used in PLC to

program the PLC

prepare the program listing

back up the program

All of the mentioned

40 / 50

An OR function implemented in ladder logic uses:

Normally-closed contacts in series

Normally-open contacts in series

A single normally-closed contact

Normally-open contacts in parallel

Normally-closed contacts in parallel

41 / 50

Current flows into the …………………………………

Input terminal of a sinking DC input module

Output terminal of a sinking output field device

Output terminal of a sinking input field device

All of the above

42 / 50

An OR function implemented in ladder logic uses:

Normally-closed contacts in series

Normally-open contacts in series

A single normally-closed contact

Normally-open contacts in parallel

Normally-closed contacts in parallel

43 / 50

The acronym PLC stands for:

Pressure Load Control

Programmable Logic Controller

Pneumatic Logic Capstan

Pressure Loss Chamber

44 / 50

Memory size in a PLC is measured in either bits, bytes or words.

Correct

Incorrect

45 / 50

When ___________ contacts are actuated, they disrupt the power supply through them.

normally open type

normally closed type

normally open and closed type

none of the mentioned

46 / 50

The output of a feedback control system must be a function of

Reference and output

Reference and input

Input and feedback signal

Output and feedback signal

47 / 50

Zero initial condition for a system means

Input reference for a system

Zero stored energy

intial movement of moving parts

system is at rest and no energy is stored in any of its components

48 / 50

Due to which of the following reasons excessive band width in control systems should be avoided ?

It leads to slow speed of response

It leads to low relative stability

Noise is proportional to band width

None of the above

49 / 50

When the accumulator value equals the register value, the relay contact is

deactivated

activated

remain the same

can’t predict

50 / 50

Regenerative feedback implies feedback with

Oscillations

Step input

Negative sign

Positive sign

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