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5th Year, Week 2 (Motor Control 3, Intro to PLC) > Intro to PLC's > Flashcards

Intro to PLC's Flashcards

1
Q

T/F: Programmers can force an output action to operate after a worker has pushed in the E-stop button.

A

True

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2
Q

What are the 4 sizes of PLC’s?

A
  1. ) Nano (Up to 32 I/O)
  2. ) Micro (32 to 128 I/O)
  3. ) Medium (128 to 960 I/O)
  4. ) Large (960 to thousands of I/O)
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3
Q

How many Inputs/Outputs can a nano-sized PLC have?

A

Up to 32

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4
Q

How many Inputs/Outputs can a micro-sized PLC have?

A

32 to 128

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5
Q

How many Inputs/Outputs can a medium-sized PLC have?

A

128 to 960

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6
Q

How many Inputs/Outputs can a large-sized PLC have?

A

960+

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7
Q

T/F: PLC’s were first used in large industrial processes and machines.

A

True

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8
Q

T/F: PLC’s are not used in commercial or residential applications.

A

False

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9
Q

A ____ occurs when any body part becomes part of an electrical circuit.

A

Electric Shock

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10
Q

T/F: All facilities have the same color code for different types of conductors/cables.

A

False, facilities will have their own code, which is important to know.

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11
Q

T/F: PLC’s can control DC, AC, or both.

A

True

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12
Q

____ grounding is the connection of an electrical system to the earth, and provides protection for the structure from lightning strikes.

A

Building Grounding

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13
Q

____ grounding is the grounding of all machinery electrical systems and all non-current carrying exposed metal to earth.

A

Equipment Grounding

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14
Q

____ grounding is establishing a quality ground to protect sensitive electronic equipment from electrical noise and fault currents.

A

Electronic Grounding

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15
Q

The NEC states that the GEC (Grounding Electrode Conductor) should have less than __ Ohms to ground.

A

25

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16
Q

T/F: The NEC states that the Electronic Grounding Conductor should have less than 5 Ohms to ground.

A

False, there is no code for grounding electronics, but it will usually be specified by the owner/engineer/manufacturer.

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17
Q

T/F: Electronic Shield drains are always grounded on both sides.

A

False

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18
Q

____ is an electrical charge at rest.

A

Static Electricity

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19
Q

Usually, it takes no more than __ Volts to destroy a circuit board, which makes PLC’s so vulnerable to ESD.

A

5V

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20
Q

The electronic ground (Shield Drain) is usually grounded at which end?

A

The end in the panel

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21
Q

A snubber circuit utilizes a ____ to suppress voltage spikes by absorbing excess voltage, and dying.

A

MOV (Metal Oxide Varistor)

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22
Q

All input devices can be put into two basic categories, ____ and ____.

A

Manual and Automatic

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23
Q

What is the most common voltage for PLC Input terminals?

A

24V

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24
Q

The ____ terminals of a PLC deliver voltage to any device or actuator controlled by the PLC.

A

Output

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25
Q

T/F: Input devices can be wired in any configuration.

A

True

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26
Q

T/F: Output devices can be wired in any configuration.

A

False, they cannot be wired in series.

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27
Q

How many Output devices can be displayed on each rung of a ladder diagram?

A

1

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28
Q

Can combination circuits be used for Input devices?

A

Yes, such as a 250 Ohm resistor between a 4-20mA system and a 1-5Vdc device.

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29
Q

Why is polarity important for both inputs and outputs?

A

Because reversed polarity can give you a negative reading, which creates issues for the PLC’s logic and for actuation of outputs.

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30
Q

PNP, switched on the positive or negative side?

Sinking or Sourcing?

A

Positive, Sourcing

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31
Q

NPN, switched on the positive or negative side?

Sinking or Sourcing?

A

Negative, Sinking

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32
Q

T/F: PLC control voltages are based on what devices are to be connected to the PLC.

A

True

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33
Q

It is important that the ____ is installed in dual-voltage rated PLC’s. (Or that the selection switch is in the correct position)

A

Jumper Link

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34
Q

A(n) ____ relay is a smaller relay (with a smaller control current) switching a larger load, such as power to a motor starter.

A

Interposing Relay

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35
Q

Why are common input voltage ratings on 12 or 24 volts?

A

Because they’re safer to work on, and require less power.

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36
Q

T/F: Most larger PLC’s have a variety of different cards.

A

True

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37
Q

What are some common Output voltage ratings?

A
  • 12v
  • 24v
  • 50v
  • 120
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38
Q

A ____ is the negative power supply terminal of a DC-powered PLC.

A

Sink

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39
Q

A ____ is the positive power supply teminal of a DC-powered PLC.

A

Source

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40
Q

____(s) are graphic representations of a device on a diagram.

A

Symbols or Glyph

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41
Q

____ symbols are drawn as very generic symbols, but with text describing the component.

A

PLC

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42
Q

“____” = Shelf State

A

Normally

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43
Q

A ____ drawing is literally a rendered picture of what the cabinet/device looks like.

A

Pictoral

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44
Q

A ____ shows the connection of all devices and components of a PLC.

A

Wiring Diagram

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45
Q

A ____ diagram has a series of single lines (rungs) that indicate the simplest representation of the control circuit logic.

A

Ladder

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46
Q

What is AND logic?

A

Two NO contacts in series, both must be closed to energize the load.

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47
Q

What is OR logic?

A

Two NO contacts in parallel, one must be closed to energize the load.

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48
Q

What is NOT logic?

A

One NC contact in series, powering the load, if the contact is opened, the load loses power.

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49
Q

What is NOR logic?

A

Two NC contacts in series, if either is opened, the load loses power.

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50
Q

What is NAND logic?

A

Two NC contacts in parallel, unless both are opened, the load will remain energized.

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51
Q

____ is when a device is wired point to point, with no use of terminals.

A

Direct Wiring

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52
Q

____ is when wires are brought to a terminal block, and from that block to its destination.

A

Terminal Wiring, this method makes it easier to trouble shoot or modify.

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53
Q

What are the 5 sections of a PLC?

A
  1. ) Inputs (Terminal Screws receiving inputs)
  2. ) Outputs (From CPU out to the devices instructed)
  3. ) CPU (Makes decisions)
  4. ) Power Supply
  5. ) Programming Device
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54
Q

The CPU of a PLC makes decisions based on what two things?

A

Input from sensors/devices, and Programmed logic/parameters.

55
Q

What is the common voltage of a PLC CPU?

A

5V

56
Q

How long can a PLC power supply last on its own when power is shut off? (Hold Up Time)

A

10ms to 3 seconds

57
Q

What are the 4 ways to program a PLC?

A
  1. ) Integrated Buttons
  2. ) HMI
  3. ) Handheld Unit
  4. ) PC (best)
58
Q

What is the difference between volatile memory and nonvolatile memory?

A

Volatile is erased when power is lost.

59
Q

What does RAM stand for?

A

Random Access Memory (Volatile)

60
Q

T/F: The program being ran on a PLC is on its RAM.

A

True

61
Q

What does EEPROM stand for?

A

Electrically Erasable Programmable Read-Only Memory

62
Q

What is a bit?

A

The smallest unit of memory.

63
Q

What is a Nibble?

A

4 Bits

64
Q

What is a Byte?

A

8 Bits

65
Q

What is a Word?

A

16 Bit

66
Q

What is the 5 step operating-cycle of a PLC?

A
  1. ) Input Scan
  2. ) Program Scan
  3. ) Output Scan
  4. ) Service Communications
  5. ) Housekeeping and Overhead
67
Q

What are the two general types of files in PLC programming?

A
  1. ) Program Files

2. ) Data Table Files

68
Q

What are the 3 Program files we are concerned with?

A

File 0 - System File
File 1 - Reserved by the Processor
File 2 - Main Program File
(Files 3-255 are subroutines)

69
Q

T/F: The first 9 Data Table files (0-8) are default files.

A

True

70
Q

Which Data Table file cannot be added to, deleted, or changed in any way?

A

Status files (File 2) or “S” type files.

71
Q

T/F: Nested branches cannot overlap.

A

True

72
Q

What does XIC stand for?

A

Examine if Closed

73
Q

What does XIO stand for?

A

Examine if Open

74
Q

What does OTE stand for?

A

Output Energize

75
Q

What do OTL and OTU stand for?

A 
OTL = Output Latch
OTU = Output Unlatch
76
Q

How do CPU’s scan the program within a PLC?

A

From Top to Bottom, Left to Right

77
Q

T/F: If you have parallel inputs, putting the path that is true most frequently on the bottom is fastest.

A

False, putting it on the top is fastest because the CPU reads from the top down.

78
Q

What two ways are addresses labeled in the book?

A
  1. ) Slot/Bit

2. ) Slot/Word/Bit

79
Q

Can outputs be placed in series?

Can they be placed in parallel?

A

Series - No (Only one per rung)

Parallel - Yes

80
Q

T/F: When timers are moved in the realm of programming, they are logic functions happening in the CPU, not actual devices.

A

True

81
Q

What are the 3 types of timer functions?

A
  1. ) TON (Timer On-Delay)
  2. ) TOF (Timer Off-Delay)
  3. ) RTO (Retentive)
82
Q 
Timer Instruction Words: What do they stand for? 
EN
TT
DN
RES
CTU
CTD
A
  1. ) Enable
  2. ) Timer Timing
  3. ) Done
  4. ) Reset
  5. ) Count Up
  6. ) Count Down
83
Q

The Count Up (CTU) and Count Down (CTD) Instructions are located in data table __.

A

5

84
Q

What Timer instruction is missing?

  • Timer Address
  • Time Base
  • Timer Preset
  • _____
A

Time Accumulated

85
Q

Timers are located in Data Table __.

A

4

86
Q

T/F: If a timer is non-retentive, it will maintain its accumulated time if it loses power.

A

False

87
Q

____ system of a building Transmits and Controls the movement of SOME form of energy.

A

Primary

88
Q

What are the 4 building system types in the book?

Besides Informational

A
  1. ) Electrical
  2. ) Electronic
  3. ) Fluid Power
  4. ) Mechanical
89
Q

A ____ device is required any time a device is not directly compatible with a PLC.

A

Interface

90
Q

A ____ system allows primary systems to work with and communicate with other building systems.

A

Interface

91
Q

____’s are different from electromechanical relays in that they don’t have coils or moving parts, and they use much less power.

A

SSR’s

92
Q

Electromechanical Relays have Coils and Contacts,

SSR’s have ____ and ____.

A

Inputs and Outputs

93
Q

A ____ is a heavy-duty relay for switching high-power loads.

A

Contactor

94
Q

A ____ is basically a contactor with overload protection.

A

Motor Starter

95
Q

T/F: According to the book, Interface devices can change one voltage level to another.

A

True

96
Q

When you receive your components for a PLC system from the supply house, and you are cross referencing to make sure you receive every part (and correct parts), what piece of documentation should you use?

A

The Purchase Order

97
Q

T/F: It is not important to pay attention to spacing and temperature limitations when installing a PLC.

A

False

98
Q

What are the 3 ways to terminate a PLC?

A
  1. ) Direct Hardwire
  2. ) Terminal Block
  3. ) Interface Devices
99
Q

T/F: Solid wire is used for wiring PLC’s , in most installations.

A

False

100
Q

____ and ____ connections should always be used with stranded wire.

A

Pin and Fork

101
Q

What is the very first thing to do when performing a Visual inspection on a PLC?

A

Lock out the disconnect. For Safety

102
Q

Maintaining a PLC is at its most basic level keeping the ____ and ____ issue free.

A

Hardware and Software

103
Q

How often should PLC software be backed up?

And generally inspected?

A

Annually

104
Q

T/F: Anyone can work on any given PLC, because they are so simple.

A

False, certified and competent technicians only.

105
Q

What are the two types of PLC maintenance inspections?

A
  1. ) Visual Inspection (De-energized)

2. ) Energized Maintenance

106
Q

What is the purpose of Energized Maintenance?

A

To verify that the Master Control Relay (MCR) is functioning correctly

107
Q

T/F: The PLC will give a notification light when the battery voltage level falls below the threshold.

A

True

108
Q

If the battery is located in the ____ card, you have to shut the PLC off to remove and replace it.

A

Processor

109
Q

If the battery is located ____, you can change it while the PLC is running.

A

Behind the hinged door or cover of the PLC

110
Q

When vacuuming any debris off of PLC components or anywhere near the PLC enclosure, it is important to use a(n) ____ safe vacuum.

A

ESD

111
Q

What are the three TYPES of PLC status lights?

A
  1. ) Input
  2. ) Output
  3. ) Operational
112
Q

What are the 5 different Operational Status lights, located on the power supply/processor of a PLC?

A
  1. ) Power
  2. ) Run Mode
  3. ) Forces
  4. ) CPU Faults
  5. ) Battery
113
Q

What are the four IEC 1010 standard classifications of Electrical Test Instruments?

A

CAT I
CAT II
CAT IIII
CAT IV

114
Q

When the CPU hits the ____ it will go back to the beginning of the program and keep only scanning to the ____ until it is removed.

A

TND

115
Q

A voltage drop of more than _____ on the PLC output supply terminals indicates that they are overloaded.

A

5%

116
Q

PLC power supply voltage should be within ____ of the rated voltage.

A

10%

117
Q

A very short unwanted voltage.

A

Transient

118
Q

A sustained increase in voltage by at least 10% for a more than 1 minute.

A

Overvoltage

119
Q

A sustained decrease in voltage by at least 10% for a more than 1 minute.

A

Undervoltage

120
Q

A sustained decrease in voltage by at least 10% for a less than 1 minute.

A

Sag

121
Q

A sustained increase in voltage by at least 10% for a less than 1 minute.

A

Swell

122
Q

Any Vacuum used on a PLC component must be ___

A

ESD safe vacuum

123
Q

What steps must be taken to safely remove a battery mounted to the processor card of a PLC?

A

LOTO
Remove card
Change battery

124
Q

When can a battery be changed on a running plc?

A

Only if the battery is located on the back of the door.

125
Q

How do you know to change the PLC battery?

A

PLC will notify you if the battery charge drops below its threshold.

126
Q

What are the 8 steps of energized maintenance?

A
  1. ) Remove LOTO
    1. ) Turn disconnect on
    2. ) Open door
    3. ) Verify that the machine or process won’t be started.
    4. ) Test the MCR
    5. ) Test and record incoming 3-phase voltage, and DC power supply voltage.
    6. ) Verify cooling fans/units are working correctly
    7. ) Check the PLC power supply and CPU indicator lights.
127
Q

Energized maintenance is done for what reason?

A

To verify correct operation of MCR or safeties

128
Q

What is the first step of visual inspection?

A

Look for damage. Just Damage. Damage.

129
Q

What are the 8 steps of visual inspections?

A
  • 1.) LOTO
    0. ) Verify that power is off
    1. ) Look for damage, physical or from heat
    2. ) Air intakes and outlets for dirt, dust, and obstructions.
    3. ) Cooling fans
    4. ) PLC and its components for dirt and contaminants
    5. ) Verify that the environment surrounding the enclosure hasn’t changed
    6. ) Inspect Input and Output devices.
    7. ) Inspect the enclosure for damage or uncapped holes.
    8. ) Tighten all connections
130
Q

Who can perform inspections or maintenance on PLCs?

A

Certified Technicians Only

131
Q

How often is maintenance performed on PLCs?

A

Annually. (remember this one)

132
Q

Why is preventative maintenance necessary for PLCs?

A

To keep Hardware and Software issue free.

133
Q

What are the two types of components you will have to maintain in a PLC?

A

Hardware and Software

134
Q

Backups of _____ is necessary to keep for PLCs.

A

Program

5th Year, Week 2 (Motor Control 3, Intro to PLC) (2 decks)

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