Training Series: Level I Introduction to Sensors Level I.
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Transcript of Training Series: Level I Introduction to Sensors Level I.
Training Series: Level ITraining Series: Level I
Introduction to SensorsIntroduction to Sensors
Level I Level I
Course Topics
• Sensors Definition• Sensor Building Blocks
– Electrical Interface• Tell me about it:
– Sensing Technology• I see it:
– Housings• Looks are everything:
Training Series: Level ITraining Series: Level I
Level IIIAdvance Problem Solving
Level IIProducts andApplications
Level ISensorBasics
Training Series: Level ITraining Series: Level I
Sensor DefinitionsSensor Definitions
What are we talking about ?
What are we talking about ?
What is a Sensor?
Used in Industrial Automation:
Electrical device capable of identifying change within an automated process.
Electrical device capable of identifying change within an automated process.
Sometimes…Sensor = SwitchSometimes…Sensor = Switch
Sensor DefinitionsSensor Definitions
Sensor Uses• Sensors in our world
– Automatic opening doors– Grocery check-out conveyer
shut-off– Safety sensors on garage doors• Sensors in
Manufacturing– Part position verification– Counting products– Liquid level control– Quality control inspection– Personal safety systems
Sensor DefinitionsSensor Definitions
Sensor Building BlocksThe three major components:
The sensing sideFront-end
Housing
The electrical sideBack-end
Sensor DefinitionsSensor Definitions
Building Block Concept
Sensor DefinitionsSensor Definitions
Sensingtechnology
Electricalinterface
Housing
most any
most any
most any
The Building Blocks
Front-end - SensingFive technology choices:
• Inductive• Optical• Capacitive• Magnetic• Mechanical
Selection base on: ApplicationSelection base on: Application
Sensor DefinitionsSensor Definitions
The Building Blocks
Back-end – ElectricalOptions:
• Electrical voltage– AC/DC– DC
• Output type– Discrete (on-off, like a switch)– Analog
Selection base on: Control SystemSelection base on: Control System
Sensor DefinitionsSensor Definitions
The Building Blocks
• The Sensors Housings– Material Options:
• Metal (nickel-plated brass)• Stainless steel• Aluminum• Plastic
– Shape (mounting style):• Tubular• Block
Selection base on: EnvironmentSelection base on: Environment
Sensor DefinitionsSensor Definitions
The Building Blocksand the real world
Sen
sing
Housing
Electrical
App
licat
ion C
ontrol System
Environment
Sensor DefinitionsSensor Definitions
Training Series: Level ITraining Series: Level I
Electrical InterfaceElectrical Interface
The Back-endThe Back-end
Electrical Interface
Divided into 2 areas:– Operating voltage
– Output signal type
Electrical InterfaceElectrical Interface
PowerPower
SignalSignal
Output Signal Types
• Discrete– ON or OFF– YES or NO
• Analog– Speed control– Position
information
MIN MAX
Electrical InterfaceElectrical Interface
SignalSignal
Operating Voltage
• Direct Current (DC)– Current flows in
only ONE direction
– Safe, easy-to-handle power source
• Alternating Current (AC)– Current changes
direction 60 times a second
– Readily available
Electrical InterfaceElectrical Interface
PowerPower
Basic Electrical Principals
What is electricity?
– Interesting fact: • Electron flow is similar to water flow • We will use this analogy during our class
Electrical InterfaceElectrical Interface
Flow (current) or potential flow (voltage) of electrons
Flow (current) or potential flow (voltage) of electrons
Basic Series CircuitUsing Water Analogy:
Water Tank
Water Valve
Hydro motor
PotentialFlowing
Electrical InterfaceElectrical Interface
Basic Series CircuitElectronics:
PotentialFlowing
+
-
BatterySwitch
Electric Motor
Basic ON or OFF operationBasic ON or OFF operation
Electrical InterfaceElectrical Interface
A discrete Sensor is a Switch
Electronics
Sensing SideFront-end
Electronics
Power WiresSwitch
Electrical InterfaceElectrical Interface
Electronics
Basic Sensor CircuitSensors with relay output
+
-
Unlike a switch, sensors require power to operate
Electrical InterfaceElectrical Interface
Types of discrete electrical outputs
• Sensors of today use Solid-State outputs, not mechanical relays
Today Yesterday
– PNP, 3-wire Relay– NPN, 3-wire– AC/DC, 2-wire
Electrical InterfaceElectrical Interface
The NPN & PNP outputFunctions similar to a switch,But current only flows in one direction
PNPTransistor Mechanical
Switch
Electrical InterfaceElectrical Interface
The Different TransistorsWhat direction do you want current to flow?
NPNAlso called Sinking
Electrical InterfaceElectrical Interface
PNPAlso called Sourcing
+--+
PNP, 3-wire
1
4+
PNP Output3 -
Load
Standard diagram formAs shown in our catalog
The Sensor
The LoadConnector
Pins
Electrical InterfaceElectrical Interface
PNP, 3-wire
1
4+
PNP Output3 -
Load
Watching the current flow
Sensors Power
Output Signal
Electrical InterfaceElectrical Interface
1
4+
NPN Output3 -
Load
NPN, 3-wireWatching the current flow
Sensors Power
Output Signal
Electrical InterfaceElectrical Interface
1 ~
3 ~
Load
The 2-wire AC/DC outputFunctions similar to a switch,
But with a small leak
Sensors Power Supply from leakage current
Output Signal
Triac
Electrical InterfaceElectrical Interface
Quick Reference:wiring PNP & NPN
N P NP N P
+
-
Load
First side of load
Second side of load
Switched side
Positive
Negative
Sensor is PNP
Electrical InterfaceElectrical Interface
If given a choice, which discrete sensor type should I choose?
PNP or NPN, 3-wire - Fewer interface
problems- Largest selection- Lowest unit costs
AC/DC, 2-wire- Many interface issues- Smaller selection- Susceptible to noise
1st CHOICE
2nd CHOICE
1
4+
3 -
Load
1 ~
3 ~
Load
Electrical InterfaceElectrical Interface
Normally Open (NO)vs.
Normally Closed (NC)Identifies the non-active state (target not present) of the sensor
Electronics
+
-
Normally Open
Is it off (open)?
Is it on (closed)?
Electrical InterfaceElectrical Interface
Normally Open (NO)vs.
Normally Closed (NC)Identifies the non-active state (target not present) of the sensor
Electronics
+
-
Is it off (open)?
Is it on (closed)?
Normally Closed
Electrical InterfaceElectrical Interface
Analog OutputsUnlike a discrete output with two defined states, analog signals have an infinite number of states.
Discrete
Analog
On
Off
Voltage
Time
Max
Min
Voltage
Time
Electrical InterfaceElectrical Interface
Analog UsesTo provide absolute measurement or position information
MeasurementPosition
Electrical InterfaceElectrical Interface
Analog Applications!What can you do with measurement information?
– Measure thickness– Position feedback– Measure tool wear– Null out machine wear– Null out thermal
expansion– Verify die position– Verify bend radius– Part profiling– Stack height
– Spool diameter– Rotational position– Liquid level– Sort parts– Determine part
orientation– Measure vibration– Measure
straightness– Hydraulic or
pneumaticcylinder position
Expanding
possibilities
Expanding
possibilities
Electrical InterfaceElectrical Interface
Analog Data• We know analog information provides:
– Measurement information– Position information
• What devices use analog information?
0 10987654321
Measurement
Panel meters Control systems
Electrical InterfaceElectrical Interface
Analog Information• The many forms for representing
measurement or position information
10
0
10
-10
5
-5
20
0
20
4
Voltage
Current
Digital Pulse
Electrical InterfaceElectrical Interface
Analog VoltageInformation contained in varying voltage
Maximum Voltage
0 10987654321
Measurement
Half Voltage
0 10987654321
Measurement
Water Analogy Volt Meter
Electrical InterfaceElectrical Interface
Analog CurrentInformation contained in varying Current
0 10987654321
Measurement
0 10987654321
Measurement
Maximum CurrentHalf Current
Water Analogy Current Meter
Electrical InterfaceElectrical Interface
Digital PulseInformation contained in digital pulse timing
100.00Maximum measurementHalf wayMinimum measurement
50.000.00Pulse Width
Meter
Start/Stop
Electrical InterfaceElectrical Interface
Measurement range
Measurement range
Electrical Interface REVIEW
• Operating voltage: Sensor Power– DC: Safest– AC: Most available
• Output signal types– Discrete
• PNP, 3-wire• NPN, 3-wire• AC/DC 2-wire
– Analog• Voltage• Current• Digital pulse
Electrical InterfaceElectrical Interface
PowerPower
SignalSignal
Training Series: Level ITraining Series: Level I
Sensing TechnologiesSensing Technologies
Sensing Technologies
Non- Contact– No physical contact with target– Preferred method for sensing end products
Contact– Contact with target– Simplest method available
Sensing TechnologiesSensing Technologies
Contact Sensing
Mechanical switch– Contact with plunger
opens electrical contacts
Contact
Sensing TechnologiesSensing Technologies
Non-Contact
Popular sensing technologies– Inductive Sensors
Metal targets– Optical Sensors
Target capable of reflecting or blocking light– Capacitive Sensors
Liquids/solids– Magnetic Field Sensors
Magnets
Sensing TechnologiesSensing Technologies
Inductive• When voltage is applied, an electromagnetic field is
generated and extends out the face of the sensor.
• When metal enters the sensing zone, an eddy current is induced in the metal.
• The change in eddy current is detected and the sensor’s output is energized.
Sensing TechnologiesSensing Technologies
• Two basic Sensing types– Flush mount
• Shorter range• Sensor can be buried in metal
– Non-flush mount• Longer range• Sensor can NOT be buried in metal
Inductive
Sensing TechnologiesSensing Technologies
OpticalRegardless of the operating mode, all optical sensors share the same operating principle:
Light emitter• Visible red• Laser• Infrared
Light receiver
OperationEmits a light beam then
detects or measures changes in received light.
Sensing TechnologiesSensing Technologies
Optical
• Optical sensors offer three main sensing modes– Thru-beam
– Retroreflective
– Diffuse
Note: There are other sensing modes available, but they are covered in other courses.
Sensing TechnologiesSensing Technologies
Optical: Thru-Beam• Separate emitter and receiver• Beam-break operation
Target blocks beam
Emitter Receiver
Great for long range and dirty environments
Sensing TechnologiesSensing Technologies
Optical: Retroreflective • Emitter and receiver in one unit• Requires a reflector• Beam-break operation
Target block light beam
Reflector
Emitter
Provides good range in well defined area
Sensing TechnologiesSensing Technologies
• Emitter and receiver in one unit• Convenient stand-alone design• Beam-make operation
Light reflects off target
Optical: Diffuse
Simple point and shoot operation
Target
Sensing TechnologiesSensing Technologies
Capacitive• Detects target based on density
Simple point and shoot operation
Target
• Electrostatic field established• Target detected when field properties change
Sensing TechnologiesSensing Technologies
Magnetic• Detects magnetic field• Magnetic field can travel through aluminum• Used extensively with pneumatic cylinders
Magnet
NS
Sees through aluminum
Sensing TechnologiesSensing Technologies
Sensing TechnologiesHead-to-Head
Mechanical:
Inductive:
Optical, Thru-beam:
Optical, Retro:
Optical, Diffuse:
Capacitive:
Magnetic:
Popular, simple
Rugged, cost-
effective
Long range
Mid range
Short range
Liquid & bulk
targets
Pneumatic
cylinders
Sensing TechnologiesSensing Technologies
Training Series: Level ITraining Series: Level I
HousingsHousings
Physical looksPhysical looks
Housing Function• Protection from environment• Mounting provisions• Electrical connection
HousingsHousings
Protection from environment
– Multiple degrees of protection liquids• IP65: Protects against water mist• IP67: Protects against temporary immersion• IP68: Protects against continuous immersion
– Multiple level of physical abuse• Metal housing• Plastic housing
HousingsHousings
Mounting Provisions• Depends on shape of housing
– Tubular• Popular for short range sensors• Range adjustments made by moving sensor in
and out
– Block• Popular for optical sensors• Easy to align horizontally and vertically
HousingsHousings
Inductive SensorInductive Sensor
Tubular HousingsEasy mounting and range adjustment
Optical SensorOptical Sensor
CapacitiveCapacitive
MagneticMagnetic
HousingsHousings
Block Housings
Provides thru-holes for mounting bolts
Allows for easy beam alignment
Inductive SensorInductive Sensor
Optical SensorOptical Sensor
BOS-SR2
HousingsHousings
Combination HousingsCombination of tubular and block housings
Inductive SensorInductive Sensor
Optical SensorOptical Sensor
HousingsHousings
Application Specific ShapesInductive SensorInductive Sensor
Optical SensorOptical Sensor
MagneticMagnetic
HydraulicCylinder
RingSensor
ValvePosition Clamp
Position
SlotSensors
WindowsFiber-optics
Pneumatic Cylinders
HousingsHousings
Electrical Connection
• Cable Out version– Economical: no additional cable to
purchase– Difficult to replace sensor
• Connector version– Cost: must purchase mating cable– Much easier to replace sensor
HousingsHousings
Cable Connection Options
• Cable Lengths– Standard lengths: 2m, 3m & 5m
• Jacket Material– PVC: Standard, low cost jacketing– PuFlex: For flexing applications
HousingsHousings
Connector Options
• Industry standard connector sizes:– Micro (M12)
• Most popular, mid-size• Available in 3, 4, 5 and 8 pins
– Nano (M8)• Smallest size• Available in 3 and 4 pins
– Mini• Largest size• Available in 3 and 4 pins
HousingsHousings
Sensor HousingsREVIEW
• Protection from environment– IP65, IP67, IP68
• Mounting provisions– Tubular, Block, Combination, Application
specific shapes• Electrical connection
– Cable out and connectors
HousingsHousings
Sensor Fundamentals
Sen
sing
Housing
Electrical
App
licat
ion C
ontrol System
Environment
Sensors DefinitionsSensors Definitions
Questions & AnswersQuestions & Answers
Training Series: Level ITraining Series: Level I
Sensor BasicsSensor Basics