All the details about pneumatics & hydraulics are available

1. PNUEMATIC &
HYDRAULIC SYSTEM
SUBMITTED TO: MR. INDERJIT SINGH
SUBMITTED BY: JHALAK NIHALANI 2018-126

2. COURSE CONTENT
• Pneumatic system and its components
• Hydraulic system and its components
• Comparison between Pneumatic and a Hydraulic system
• Types of control valves used in Pneumatics and Hydraulics
• Industrial applications of Pneumatic systems
• Industrial applications of Hydraulic systems

3. PNEUMATIC SYSTEM
• Pneumatics is a branch of engineering that makes use of gas or
pressurized air.
• Pneumatic systems are commonly powered by compressed air or
inert gases. Compressor powers cylinders, air motors, pneumatic
actuators, and other pneumatic devices.
•Pneumatics also has applications in dentistry, construction, mining,
and other areas.

4. GASES USED IN PNEUMATIC SYSTEM
• Pneumatic system uses compressed air because sustainable supply
can be made by compressing atmospheric air.
• The air usually has moisture removed, and a small quantity of oil is
added at the compressor to prevent corrosion and lubricate
mechanical components.
• Pneumatic-power users need not worry about poisonous leakage,
as the gas is usually just air.
• Small systems can use other compressed gases often refered to
as OFN (oxygen-free nitrogen).

5. ADVANTAGE OF PNEUMATIC
SYSTEM
•Pneumatic tools when over loaded will stop and so safe, as compared to electrical
system.
•No fire hazard as in Electrical Systems. So cab be easily used in dangerous areas like
mines.
•Simple in construction, the pneumatic system components are easy to maintain and
repair.
•The speeds and forces are infinitely variable.
•Force is limited by air pressure and cylinder diameter.
•The speed and forces are infinitely variable.
•Simple and easy to control.

6. PROPERTIES OF COMPRESSED AIR
• Widely available
• Easy transportation
• No storage issue
• Non explosive
• Economical
• Reliable & durable
• Environment friendly
• Clean
• Safe to use

7. DISADVANTAGE OF COMPRESSED
AIR
•Preparation- Compressed air requires more preparation. Dirt and
condensate should not be present.
•Compressible- Not always possible to achieve uniform and constant
speeds with compressed air.
•Force requirement- Compressed air economical up to a certain force
requirement.
•Noise level- Exhaust air is loud.
•Costs- compressed air is a relatively expensive of conveying power.

8. GENERAL PNEUMATIC APPLICATIONS
• Train doors
• Automatic production lines
• Mechanical clamps
• Dismantling vehicle tires
• Transporting goods
• Air brakes on heavy vehicles
• Packaging
• Machine operations like drilling

9. SOME MORE PNEUMATIC APPLICATIONS
Switch for two conveyor belts Pneumatic cutter

10. FACTORS DURING DEVELOPMENT OF
PNEUMATIC SYSTEM
•Durability
•Cost
•Ease of maintenance
•Economic efficiency
•Compact design
•Reliability

11. PNEUMATIC SYSTEM STRUCTURE AND
SIGNAL FLOW
PRIMARY LEVELS OF PNEUMATIC
Energy Supply
Input Elements
Processing Elements
Actuating Devices
Control Elements

13. ELECTROPNEUMATIC
CONTROLLERS:
The control of pneumatic components by electrical impulses is known as electro-pneumatics.
In electropneumatic control systems, the control system cannot be depicted in one overall circuit
diagram as in a purely pneumatic control system, but rather using two separate circuit diagrams, one
for the pneumatic section and one for the electrical components.
The following rough description applies for the operation of an electropneumatic control system.
Higher reliability due to the lower number of mechanical parts that are required to move or are
subject to wear and tear.
Less efforts and expense for planning and commissioning.
Less time required for installation, particularly when using more modern, more compact assemblies
like valve terminals.
simple and rapid modification of open and close-loop control strategies using programmable logic
control.
Easy exchange of information between several control systems.

14. STRUCTURE OF ELECTRO-PNEUMATIC FINAL
CONTROL ELEMENT:

15. ADVANTAGES OF ELECTRO-PNEUMATIC
CONTROLLERS OVER PNEUMATIC CONTROLLER:
•No time lag or transmission delay.
•Linear and quick response and good accuracy.
•No entrainment or contamination in control medium.
•Higher reliability.
•Simpler exchange of information between several controllers.

16. PRIMARY LEVELS IN A
PNEUMATIC SYSTEM
•Energy supply
•Input element (sensor)
•Processor
•Control element (DCV)
•Actuator

17. ASPECTS CONSIDERED IN
PREPARATION OF SERVICE AIR
•Quantity of air
•Type of compressor used
•Pressure required
•Requirement of clean air
•Material selection for eco-friendly environment
•Layout of distribution system

18. COMBINATIONAL CONTROL:

19. SELECTION CRITERIA FOR THE CONTROL
SYSTEM:
•Reliability of components
•Sensitivity to environment influences
•Ease of maintenance and repair
•Switching time of components
•Signal speed
•Space requirement
•Service life
•Training requirements of operators and maintainers
•Modification of control system

21. COMPONENTS OF A PNEUMATIC SYSTEM
•Compressor
•Check valves
•Actuators
•Pneumatic DCV
•Cooler
•Regulator and gauges
•Air receiver

22. PNEUMATIC SYSTEM DIAGRAM

23. COMPONETS OF PNEUMATIC SYSTEM :
Air filters: These are used to filter out the contaminants from the air.
Compressor: Compressed air is generated by using air compressors. Air compressors are
either diesel or electrically operated. Based on the requirement of compressed air, suitable
capacity compressors may be used.
Air cooler: During compression operation, air temperature increases. Therefore coolers are
used to reduce the temperature of the compressed air.
Dryer: The water vapor or moisture in the air is separated from the air by using a dryer.
Control Valves: Control valves are used to regulate, control and monitor for control of
direction flow, pressure etc.

24. COMPONETS OF PNEUMATIC SYSTEM :

25. COMPONETS OF PNEUMATIC SYSTEM :
Air Actuator: Air cylinders and motors are used to obtain the required movements of mechanical
elements of pneumatic system
Electric Motor: Transforms electrical energy into mechanical energy. It is used to drive the
compressor.
Receiver tank: The compressed air coming from the compressor is stored in the air receiver.
Actuator: The actuator is a pneumatic engine that produces outward power through inconsistent
weight in a pneumatic cylinder, frequently associated with a piston pole assembly. Pneumatic
cylinders are of numerous kinds. Those that utilize piston rods are isolated into single acting and
double acting cylinders

26. COMPONENTS OF A PNEUMATIC SYSTEM:

27. STAGES OF AIR TREATMENT:

28. COMPRESSOR
A compressor is a mechanical device that increases the pressure of a
gas by reducing its volume.

29. AIR RECEIVER CRITERIA OF SELECTION
•Delivery Volume of the Compressor
•Amount of Air Consumption
•Pipeline Network
•Type and nature of regulation
•Permissible pressure difference in the pipelines

30. AIR RECEIVER SPECIFICATIONS
•Provision for Safety Relief Valve
•Material consideration
•Standard Port Sizes for interconnection
•Storage Capacity
•Inspection Manhole provision
•Manual/ Auto Drain Valve provision
•Maximum Operating Pressure
•Pressure Gauge
•Shut off Valve for Isolation

31. TYPES OF AIR COMPRESSORS
•Positive displacement compressors
•Dynamic displacement compressors

32. POSITIVE DISPLACEMENT COMPRESSORS
•Piston compressors
•Diaphragm compressors
•Screw compressors
•Rotary vane compressor

33. PISTON COMPRESSOR
A piston compressor is a positive-
displacement compressor that uses pistons driven by a
crankshaft to deliver gases at high pressure. Applications
include oil refineries, gas pipelines, chemical plants,
natural gas processing plants, air conditioning, and
refrigeration plants.

34. DIAPHRAGM COMPRESSOR
A diaphragm compressor is a variant
of the classic reciprocating compressor
with backup and piston rings and rod
seal. The compression of gas occurs by
means of a flexible membrane, instead
of an intake element. The back and forth
moving membrane is driven by a rod
and a crankshaft mechanism.

35. SCREW COMPRESSOR
A rotary-screw compressor uses a rotary-type
positive-displacement mechanism. These
compressors are common in industrial applications
and replace piston compressor where larger volumes
of compressed gas are needed, e.g. for large
refrigeration cycles such as chillers.
For smaller rotor sizes the inherent leakage in the
rotors becomes much more significant, leading to this
type of mechanism being less suitable for smaller
compressors than piston compressors.
The gas compression process of a rotary screw is a
continuous sweeping motion. This also allows screw
compressors to be significantly quieter and produce
much less vibration than piston compressors, even at
large sizes, and produces some benefits in efficiency.

36. VANE COMPRESSOR
This is a positive-displacement pump that
consists of vanes mounted to a rotor that
rotates inside a cavity.
The vane-type compressor consists of a
cylindrical rotor.

37. TECHNICAL SPECIFICATIONS OF
AIR COMPRESSOR
•Type of Air Compression requirement (Oil based/ Oil free)
•Working Pressure (Minimum & Maximum in PSIG)
•Delivery Capacity (CFM)
•AC Motor Specifications, Starter & Protection Requirement
•Pressure Switch for Automatic Operation (Low Cut in and High Cut Out)
•Air Receiver with PRV, Pressure Gauge, Drain
•NRV, Shut off Valves
•Noise Level requirement
•Duty Cycle

38. COMPESSOR REGULATION
METHOD:
In a lot of cases, applications require constant pressure in the compressed air
system.
This, in turn, requires that the compressed air flow from the compressor
center is regulated.

39. PRESSURE RELIEF METHOD:
The original method for regulating compressors was to use a pressure relief valve
to release excess air pressure into the atmosphere.
The valve in its simplest design can be spring-loaded, whereby the spring tension
determines the final pressure.
Frequently a servo-valve controlled by a regulator is used instead. The pressure
can then be easily controlled and the valve can also act as an off-loading valve
when starting a compressor under pressure.
Pressure relief creates a significant energy requirement, as the compressor must
work continuously against full counterpressure. A variant, which is used on
smaller compressors, is to unload the compressor by fully opening the valve so
that the compressor works against atmospheric pressure.
Power consumption is significantly lower using this variant method.

40. BYPASS REQULATION:
Bypass regulation serves the same function as pressure relief, in principle.
The difference lies in the fact that the pressure relieved air is cooled and returned to the
compressor's inlet.
This method is often used on process compressors where the gas is unsuitable or too valuable to
be released into the atmosphere

41. THROTTLING
Throttling is a simple method to reduce flow by increasing the pressure ratio across the compressor,
according to the induced under-pressure in the inlet.
This method is, however, limited to a small regulation range. Liquid-injected compressors, which can
overcome such a high pressure ratio, can be regulated down to 10% of maximum capacity.
The throttling method creates a relatively high energy requirement, due to the high pressure ratio.

42. HYDRAULIC SYSTEM
A hydraulic system is a drive technology where a fluid is used to move
the energy from motor to an actuator, such as a hydraulic cylinder. The
fluid is theoretically uncompressible and the fluid path can be flexible in
the same way as an electric cable.

43. ACTUATORS:
Actuators are devices used to produce action or motion.
It is operated by a source of energy and converts that energy into motion.
It is mechanism by which a control system acts upon environment.
Actuator functional diagram:

44. LINEAR ACTUATORS:
Provides motion in straight line.
Linear displacement depends on
stroke length.
Usually referred to as cylinders, rams
( single acting cylinders) or jacks.

45. ROTARY ACTUATORS :
Produce continuous rotational
motion.
Pump shafts is rotated to
generate flow.
Motor shaft is caused to rotate
by fluid being forced into driving
chambers.

46. FLOW RATE :

47. FLOW RATE :

48. DIRECTION OF MOVEMENT:

49. DIRECTION OF MOVEMENT:

50. PASCAL’S LAW
Pascal’s principle, also called Pascal’s
law, in fluid (gas or liquid)
mechanics, statement that, in a fluid
at rest in a closed container,
a pressure change in one part is
transmitted without loss to every
portion of the fluid and to the walls
of the container. The principle was
first enunciated by the French
scientist Blaise Pascal.

51. BERNOULLI’S PRINCIPLE
In fluid dynamics, Bernoulli's principle states that an increase in the speed of a fluid occurs
simultaneously with a decrease in static pressure or a decrease in the fluid's potential energy

52. ADVANTAGES OF HYDRAULIC SYSTEMS
•Variable speed
•Reversible
•Overload protection
•Small packages
•Can be stalled
•High Efficiency
•Consistent Power Output

53. PROPERTIES OF HYDRAULIC FLUID
•Stable and optimum viscosity
•Thermal stability
•Low compressibility
•Good lubrication
•Low pour point
•Filterability
•Rust, oxidation & corrosion protection properties
•High flash point
•Resistant to fire
•Low foaming to prevent cavitation

54. REQUIREMENTS OF FLUID IN POWER
TRANSMISSION:
•Low cost
• Non-corrosive
•Have infinite stiffness
•Good lubrication properties
•Store well without degradation
•Non-toxic
• Non-inflammable
• Properties remain stable over wide range of temperatures

55. COMPONENTS OF A HYDRAULIC SYSTEM
•Sump
•Filters
•Hydraulic pump
•Pressure Regulator
•Hydraulic DCVs
•Hydraulic actuators

56. HYDRAULIC SYSTEM DIAGRAM

57. TYPES OF HYDRAULIC PUMPS
•Non-positive displacement pumps
•Positive displacement pumps

58. NON-POSITIVE DISPLACEMENT PUMPS
A non-positive-displacement pump produces a continuous flow.
However, because it does not provide a positive internal seal against
slippage, its output varies considerably as pressure varies. Centrifugal
pumps is example of non-positive displacement pump.

59. REQUIREMENTS OF FLUID IN POWER
TRANSMISSION:
Low cost
Non-corrosive
Have infinite stiffness
Good lubrication properties
Store well without degradation
Non-toxic
Non-inflammable
Properties remain stable over wide range of temperatures

60. HYDRO-DYNAMIC PRINCIPLE:
The hydrodynamic principles that deal
with the mechanics of fluid flow and the
derivations are based on three
conservation principles: Mass,
momentum and energy.

61. CENTRIFUGAL PUMP
A centrifugal pump is a mechanical device
designed to move a fluid by means of the
transfer of rotational energy from one or more
driven rotors, called impellers. Fluid enters
the rapidly rotating impeller along its axis and
is cast out by centrifugal force along its
circumference through the impeller's vane
tips.

62. POSITIVE DISPLACEMENT
HYDRAULIC PUMPS
•Hydraulic Gear pumps
•Hydraulic Vane pumps
•Hydraulic Piston type pumps

63. HYDROSTATICS PRINICLES:
Hydrostatics is the branch of fluid
mechanics that studies "fluids at rest and
the pressure in a fluid or exerted by a fluid
on an immersed body“.
the principles of hydrostatics are used for
problems relating to pressure in deep
water (pressure increases with depth) and
high in the atmosphere (pressure lessens
with altitude).

64. HYDRAULIC GEAR PUMPS
A gear pump uses the meshing of gears to pump fluid by displacement . They are one
of the most common types of pump for hydraulic fluid power applications.
Gear pumps are also widely used in chemical installations to pump high viscosity fluids.
There are two main variations: external gear pumps which use two external spur gears,
and internal gear pumps which use an external and an internal spur gears

65. EXTERNAL GEAR PUMP

66. INTERNAL GEAR PUMP

67. HYDRAULIC VANE PUMPS
Vane pumps are hydraulic pumps that operate at very low noise levels. Hydraulic vane
pumps operate with much lower flow pulsation, i.e. constant flow. As such, vane
pumps produce less noise while maintaining a relatively high speed of up to 3,000 rpm.

68. HYDRAULIC PISTON TYPE PUMPS
Piston pumps are the hydraulic pumps with the highest pressure rating and best overall
efficiency. Hydraulic piston pumps operate at very high volumetric efficiency levels due
to low fluid leakage. The plungers may consist of valves at the suction and pressure
ports or with input and output channels.

69. Fixed Delivery
Pumps
Gear Pumps
Balanced
Vane Pumps
Unbalanced
Vane Pumps
Axial Piston
Pumps
Radial Piston
Pumps
Variable Delivery Pumps
Axial Piston Pumps
Unbalanced Vane
Pumps
Radial Piston Pumps

70. COMPARISON BETWEEN PNEUMATIC
AND A HYDRAULIC SYSTEM
S.N. Pneumatic Systems Hydraulic Systems
1. Required for Clean Equipments Required for Heavy Equipments
2. Requires Air compressors to work Requires Hydraulic Pumps to work
3. Faster Speed of Operation Slow and Controlled Movement of Actuators
4. Operating Pressures of 10 – 20 bars Much higher Operating Pressures
5. Relatively Low Cost More Expensive
6. Light weight components and Smaller in
Size
Heavier Components and Larger in Size
7. Safe from Fire Hazards Unsafe to Fire Hazards
8. Requires Air Receiver for Proper Operation Uses Accumulators for working properly
9. Open Loop Operation as DCVs are Vented Closed Loop Operation
10. Applications involve SEM, PECVD etc. Applications involve Drilling, Punching etc.

71. COMPARISON OF PNEUMATIC, HYDRAULIC &
ELECTRICAL SYSTEMS

74. TYPES OF CONTROL VALVES USED IN
PNEUMATICS AND HYDRAULICS
Direction control valves (DCVs)
 Pressure control valves (PCVs)
 Flow control valves (FCVs)

75. TECHNICAL SPECIFICATIONS OF A DCV
•Pneumatic/ Hydraulic DCV
•5/2 v/s 4/3 (Number of Ports and No. of Positions)
•Number of Ways
•Pressure Rating
•Port Size
•Type of Actuation used
•Mono-stable v/s Bi-stable DCVs

76. VALVES BASED ON TYPE OF
CONSTRUCTION
•Poppet valves
•Spool valves

77. POPPET VALVES

78. POPPET VALVES
• Unidirectional
• No leakage
• Can be used with highest pressures
• Long useful life
• Simple in construction & inexpensive
• In line and right angle design options

79. SPOOL VALVES

80. VALVES BASED ON NUMBER OF
WORKING PORTS
•Two way valves
•Three way valves
•Four way valves

81. 2 WAY DCV

82. 3 WAY DCV
3/2 DCV

83. 4 WAY DCV
4/2 DCV

84. VALVES BASED ON NUMBER OF
SWITCHING POSITIONS
•Two position valves
•Three position valves

85. 2 POSITION 4 WAY DCV

86. 3 POSITION 4 WAY DCV

87. Manual Actuation :

88. MECHANICAL ACTUATION

89. PRESSURE CONTROL VALVES
•Pressure relief valve
•Unloading valve
•Pressure sequence valve
•Counterbalance valve
•Pressure reducing valve

90. PRESSURE RELIEF VALVE
A pressure relief valve (PRV) is a type of safety
valve used to control or limit the pressure in a system;
pressure might otherwise build up and create a
process upset, instrument or equipment failure, or fire.
The pressure is relieved by allowing the pressurized
fluid to flow from an auxiliary passage out of the
system.
PRV symbol

91. UNLOADING VALVE
Unloading valve symbol
Unloading valves are pressure-control devices
that are used to dump excess fluid to tank at little
or no pressure. A common application is in hi-lo
pump circuits where two pumps move an actuator
at high speed and low pressure

92. PRESSURE SEQUENCE VALVE
Pressure sequence valve symbol
A sequence valve is a pressure
valve designed to open when its set pressure is
reached, providing a path of flow alternate and
sequential to the primary circuit. In some ways,
a sequence valve is a directional valve,
allowing flow to occur.

93. COUNTERBALANCE VALVE
Counter balance valve symbol
Counterbalance valves are used with
cylinders to safely hold suspended loads and
deal with over-running loads. This valve can
also be used with hydraulic motors and is
then commonly called a brake valve

94. PRESSURE REDUCING VALVE
Pressure reducing valve symbol
Pressure Reducing Valves are designed to
reduce incoming water or steam pressure to a
safer constant predetermined downstream level.
Depending on the type of valve, the downstream
pressure is established by a pressure adjustment
setting on the valve or by an external sensor.

95. FLOW CONTROL VALVES
Plug Valve Needle Valve Glove Valve

96. TYPES OF CYLINDERS
Single acting cylinder symbol Double acting cylinder symbol

98. DOUBLE ACTING CYLINDER
A double-acting cylinder is a cylinder in which the working fluid acts alternately on both
sides of the piston. In order to connect the piston in a double-acting cylinder to an
external mechanism, such as a crank shaft, a hole must be provided in one end of the
cylinder for the piston rod, and this is fitted with a gland or "stuffing box" to prevent
escape of the working fluid. Double-acting cylinders are common in steam engines but
unusual in other engine types. Many hydraulic and pneumatic cylinders use them where
it is needed to produce a force in both directions. A double-acting hydraulic cylinder has
a port at each end, supplied with hydraulic fluid for both the retraction and extension of
the piston. A double-acting cylinder is used where an external force is not available to
retract the piston or it can be used where high force is required in both directions of
travel.

99. TYPES OF SENSORS USED WITH
CYLINDERS

100. SUPPLY COMPONENT SYMBOLS

101. SERVICE UNIT SYMBOLS

102. COMBINED UNIT SYMBOLS

103. MORE SYMBOLS

104. INTRODUCTION
Power Supply - This can be built into the PLC or be an external unit. Common
voltage levels required by the PLC (with and without the power supply) are
24Vdc, 120Vac, 220Vac.
CPU (Central Processing Unit) - This is a computer where ladder logic is stored
and processed.
I/O (Input / Output) - A number of input/output terminals must be provided so
that the PLC can monitor the process and initiate actions.
Indicator lights - These indicate the status of the PLC including power on,
program running, and a fault. These are essential when diagnosing problems.

105. BASIC TYPES OF PLC
Rack Type - A rack is often large (up to 18” by 30” by 10”) and can hold multiple
cards. When necessary, multiple racks can be connected together. These tend to
be the highest cost, but also the most flexible and easy to maintain.
Mini PLC - These are similar in function to PLC racks, but about half the size.
Shoebox Type - A compact, all-in-one unit (about the size of a shoebox) that
has limited expansion capabilities. Lower cost, and compactness make these
ideal for small applications.
Micro PLC - These units can be as small as a deck of cards. They tend to have
fixed quantities of I/O and limited abilities, but costs will be the lowest.

106. I/O TYPES
Inputs to, and outputs from, a PLC are necessary to monitor and control a process.
Both inputs and outputs can be categorized into two basic types: logical or continuous.
Outputs to actuators allow a PLC to cause something to happen in a process. A short list
of popular actuators is given below in order of relative popularity.
Solenoid Valves - logical outputs that can switch a hydraulic or pneumatic flow.
Indicator Lights - logical outputs that can often be powered directly from PLC output
boards.
Motor Starters - motors often draw a large amount of current when started, so they
require motor starters, which are basically large relays.
Servo Motors - a continuous output from the PLC can command a variable speed or
position.

107.  Outputs from PLCs are often relays, but they can also be solid state
electronics such as transistors for DC outputs or Triacs for AC outputs.
Continuous outputs require special output cards with digital to analog
converters.
 Inputs come from sensors that translate physical phenomena into electrical
signals. Typical examples of sensors are listed below in relative order of
popularity.
 Proximity Switches - use inductance, capacitance or light to detect an object
logically.
 Switches - mechanical mechanisms will open or close electrical contacts for a
logical signal.
 Potentiometer - measures angular positions continuously, using resistance.
 LVDT (linear variable differential transformer) - measures linear displacement
continuously using magnetic coupling.

108. SOURCING/SINKING
Sinking -When active the output allows current to flow to a
common ground. This is best selected when different voltages are
supplied.
Sourcing - When active, current flows from a supply, through the
output device and to ground. This method is best used when all
devices use a single supply voltage.

109. INPUT VOLTAGES
In smaller PLCs the inputs are normally built in and are specified when purchasing the PLC. For
larger PLCs the inputs are purchased as modules, or cards, with 8 or 16 inputs of the same type
on each card. The list below shows typical ranges for input voltages, and is roughly in order of
popularity.
12-24 Vdc
100-120 Vac
10-60 Vdc
12-24 Vac/dc
5 Vdc (TTL)
200-240 Vac
48 Vdc
24 Vac

110. INPUT CARD SELECTION
 There are many trade-offs when deciding which type of input cards to use.
 DC voltages are usually lower, and therefore safer (i.e., 12-24V).
 DC inputs are very fast, AC inputs require a longer on-time. For example, a
60Hz wave may require up to 1/60sec for reasonable recognition.
 DC voltages can be connected to larger variety of electrical systems.
 AC signals are more immune to noise than DC, so they are suited to long
distances, and noisy (magnetic) environments.
 AC power is easier and less expensive to supply to equipment.
 AC signals are very common in many existing automation devices.

111. OUTPUT MODULE
As with input modules, output modules rarely supply any power, but instead act as
switches. External power supplies are connected to the output card and the card will
switch the power on or off for each output. Typical output voltages are listed below,
and roughly ordered by popularity.
•120 Vac
•24 Vdc
•12-48 Vac
•12-48 Vdc
•5Vdc (TTL)
•230 Vac

112. OUTPUT CARDS
These cards typically have 8 to 16 outputs of the same type and can
be purchased with different current ratings. A common choice when
purchasing output cards is relays, transistors or triacs. Relays are the
most flexible output devices. They are capable of switching both AC
and DC outputs. But, they are slower (about 10ms switching is
typical), they are bulkier, they cost more, and they will wear out after
millions of cycles. Relay outputs are often called dry contacts.
Transistors are limited to DC outputs, and Triacs are limited to AC
outputs. Transistor and triac outputs are called switched outputs.

113. OUTPUT CARDS
Dry contacts - a separate relay is dedicated to each output. This
allows mixed voltages (AC or DC and voltage levels up to the
maximum), as well as isolated outputs to protect other outputs and
the PLC. Response times are often greater than 10ms. This method is
the least sensitive to voltage variations and spikes.
Switched outputs - a voltage is supplied to the PLC card, and the
card switches it to different outputs using solid state circuitry
(transistors, triacs, etc.) Triacs are well suited to AC devices requiring
less than 1A. Transistor outputs use NPN or PNP transistors up to 1A
typically. Their response time is well under 1ms.

114. OUTPUT CARDS
A major issue with outputs is mixed power sources. It is good
practice to isolate all power supplies and keep their commons
separate, but this is not always feasible. Some output modules, such
as relays, allow each output to have its own common. Other output
cards require that multiple, or all, outputs on each card share the
same common. Each output card will be isolated from the rest, so
each common will have to be connected.

118. TTL
Transistor-Transistor Logic (TTL) is based on two voltage levels, 0V for
false and 5V for true. The voltages can actually be slightly larger than
0V, or lower than 5V and still be detected correctly. This method is
very susceptible to electrical noise on the factory floor, and should
only be used when necessary. TTL outputs are common on electronic
devices and computers, and will be necessary sometimes. When
connecting to other devices simple circuits can be used to improve
the signal, such as the Schmitt trigger.

119. SCHMIDT TRIGGER

120. SCHMIDT TRIGGER
A Schmitt trigger will receive an input voltage between 0-5V and
convert it to 0V or 5V. If the voltage is in an ambiguous range, about
1.5-3.5V it will be ignored.
If a sensor has a TTL output the PLC must use a TTL input card to
read the values.
If the TTL sensor is being used for other applications it should be
noted that the maximum current output is normally about 20mA.

121. SINKING/ SOURCING
Sinking sensors allow current to flow into the sensor to the voltage
common, while sourcing sensors allow current to flow out of the sensor
from a positive source. For both of these methods the emphasis is on
current flow, not voltage. By using current flow, instead of voltage, many
of the electrical noise problems are reduced.
When discussing sourcing and sinking we are referring to the output of
the sensor that is acting like a switch. In fact the output of the sensor is
normally a transistor, that will act like a switch (with some voltage loss). A
PNP transistor is used for the sourcing output, and an NPN transistor is
used for the sinking input.

122. SINKING/ SOURCING
The term sourcing is often interchanged with PNP, and sinking with NPN.
A simplified example of a sinking output sensor is shown in Figure 4.3. The
sensor will have some part that deals with detection, this is on the left.
The sensor needs a voltage supply to operate, so a voltage supply is
needed for the sensor. If the sensor has detected some phenomenon then
it will trigger the active line. The active line is directly connected to an
NPN transistor.
(Note: for an NPN transistor the arrow always points away from the
center.) If the voltage to the transistor on the active line is 0V, then the
transistor will not allow current to flow into the sensor. If the voltage on
the active line becomes larger (say 12V) then the transistor will switch on
and allow current to flow into the sensor to the common.

123. SINKING SENSOR

124. SOURCING SENSOR

125. SOURCING/SINKING

126. PNEUMATIC AND HYDRAULIC
EXPERIMENTS PERFORMED IN LAB

127. Q2. Design ladder logic for reciprocating motion of a
single acting cylinder using start and stop button.

128. Q3. Design Ladder Logic for reciprocating motion of a
double acting cylinder using start and stop button.

129. Q5. Design Ladder Logic for a circuit such that motor
starts after 5 seconds of pressing start button and
keeps running until stopped by a stop button.

130. Q6. Design Ladder Logic for a circuit such that motor
runs for 5 seconds on pressing start button and then
stops.

131. Q7. Design Ladder Logic for a circuit such that motor
starts after 5 seconds of pressing start button, runs for
a period of 5 seconds and then stops.

132. Q8. Design a ladder logic for a circuit in which the
cylinder performs an extension stroke after pressing
start button 3 times and retracts automatically.

133. Q9. Design a ladder logic for a circuit in which the cylinder
performs an extension stroke 5 seconds after pressing start
button 3 times and retracts automatically.

134. Q10. Design a ladder logic for a circuit in which the
cylinder reciprocates for a period of 30 seconds, on
pressing the start button thrice.

135. Q 26 :Design a ladder logic for sequencing
operation of two hydraulic cylinders.

136. Q 27 :Design a ladder logic for delayed
operation of two hydraulic cylinders.

137. Q29: Design ladder logic to start a hydraulic motor on
the count of 5 extensions hydraulic cylinder keep bit
running indefinitely.

138. Q30: Design ladder logic to start a hydraulic motor 5
seconds after counting 5 extensions hydraulic cylinder
keep bit running indefinitely.

139. Q31: Design ladder logic to start a hydraulic motor on
the count of 5 extensions hydraulic cylinder and stops
after 5 rotation.

140. Q32: Design ladder logic to start a hydraulic motor
on the count of 5 extensions hydraulic cylinder and
revers its direction after 5 rotations.

141. Q33: Design ladder logic to start a hydraulic motor on the
count of 5 extensions hydraulic cylinder and keep on
alternating its direction of rotation after every 5 rotation.

142. Q34: Design ladder logic to start a hydraulic motor on
the count of 5 extensions hydraulic cylinder and stops
after 5 seconds.

143. Q35: Design ladder logic to start a hydraulic motor on
the count of 5 extensions hydraulic cylinder and
reverses its direction after 5 seconds.

144. WIRING DIAGRAM OF PNEUMATIC KIT

145. THANKYOU