Sensors (Festo )

8/4/2019 Sensors (Festo )

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17.10.03 No. 1 / 91 Festo Didactic Training and Consulting Sensors

Optical - Diffuse

Inductive

Reed switch

Inductive magnetic

Capacitive

Symbols

Connection

Optical Through-beam

Optical Retro-reflective

Proximity sensors


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Type : Through-beam

Optical sensors (Through-beam)


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Transmitter Receiver

Type : Through-beam



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Type : Through-beam



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Target


Type : Through-beam



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Type : Through-beam



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Type : Through-beam



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Type : Through-beam



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Type : Through-beam



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Type : Through-beam



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Type : Through-beam



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Type : Through-beam



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Type : Through-beam



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Target

Long sensing distance: up to 30 metres with some devices

Will detect all but very transparent materials

Must be accurately aligned


Type : Through-beam



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Optical sensors (Retro-reflective)


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Reflector

(prismatic)

T

R


Type : Retro reflective

Transmitter

/Receiver


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Reflector

(prismatic)

T

RTransmitter

/Receiver




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Reflector

(prismatic)

T

RTransmitter

/Receiver




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Reflector

(prismatic)

Target

T

RTransmitter

/Receiver




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Reflector

(prismatic)

T

RTransmitter

/Receiver




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Reflector

(prismatic)

T

RTransmitter

/Receiver




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Reflector

(prismatic)

T

RTransmitter

/Receiver




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Reflector

(prismatic)

T

RTransmitter

/Receiver




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Reflector

(prismatic)

T

RTransmitter

/Receiver




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Reflector

(prismatic)

T

RTransmitter

/Receiver




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Reflector

(prismatic)Sensing distance : 1/2 to 1/3 of through-beam type

Not suitable for reflective or transparent targets

Target should be larger than the reflector

T

R


Transmitter

/Receiver



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Type : Diffuse

Optical sensors (Diffuse)


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Target

T

RTransmitter

/Receiver


Type : Diffuse


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T

RTransmitter

/Receiver


Type : Diffuse


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T

RTransmitter

/Receiver


Type : Diffuse


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T

RTransmitter

/Receiver


Type : Diffuse


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T

RTransmitter

/Receiver


Type : Diffuse


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T

RTransmitter

/Receiver


Type : Diffuse


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Transmitter

/Receiver

Sensing distance: much less than reflex type, actual distance depends on colour and

reflective nature of the surface

Larger targets result in longer sensing distances

Not suitable for dirty environments

T

R


Type : Diffuse


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Inductive sensors


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Connection cable

LED indicator

Resonant circuit coil

Active surface

High frequency magnetic

field

(300 to 800 kHz)

Inductive sensors


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Sensor

Oscillation

Amplitude

Sensor

output

signal

ON

OFF

Targe

t

Inductive sensors


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ON

OFF

Target

Sensor

Oscillation

Amplitude

Sensor

output

signal

Inductive sensors


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ON

OFF

Target

Sensor

Oscillation

Amplitude

Sensor

output

signal

Inductive sensors


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ON

OFF

Target

Sensor

Oscillation

Amplitude

Sensor

output

signal

Inductive sensors


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ON

OFF

Target

Sensor

Oscillation

Amplitude

Sensor

output

signal

Inductive sensors


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ON

OFF

Target

Sensor

Oscillation

Amplitude

Sensor

output

signal

Inductive sensors


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ON

OFF

Target

Sensor

Oscillation

Amplitude

Sensor

output

signal

Inductive sensors


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ON

OFF

Target

Sensor

Oscillation

Amplitude

Sensor

output

signal

Inductive sensors


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ON

OFF

Target

Sensor

Oscillation

Amplitude

Sensor

output

signal

Inductive sensors


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Will detect any conductive material

Quoted distances are for mild steel

Sensor performance can be affected by:

Temperature

Target material

Target dimensions

Inductive sensors


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Reed switch


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Glass Tube filled

with nitrogen

Reed

contacts

LED

indicator

Reed switch


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Reed switch


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Reed switch


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Reed switch


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Reed switch


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Reed switch


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Reed switch


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24v

Reed switch


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24v

Reed switch


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Interference from other magnetic fields must be avoided.

If positioned in mid stroke, switching point will vary depending on direction of approach.

Maximum current must be limited to avoid burning of the reed contacts.

Reed switch


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Inductive magnetic sensor


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Connection

cable

LED

Indicator

Resonant circuit

coil

High

frequency

magnetic

field



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Inductive principle of operation - but only reacts to magnetic fields

Interference from other magnetic fields must be avoided.

Solid state device - higher switching frequency - 1kHz



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Capacitive sensor


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Connection cable

Adjusting screw

LED indicator

Active surface

Active electrode

Earth electrode

Electrostatic fieldSensor is looking for a

change in capacitance in the

active field

Capacitive sensor


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TargetCapacitive sensor


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Capacitive sensor


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Capacitive sensor


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Capacitive sensor


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Detects any material denser than air (as

long as there is enough of it)

Can be adjusted for sensitivity

Can be affected by dusty environments

Capacitive sensor


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Sensor is adjusted so that

it does not see the wall ofthe vessel.

Capacitive sensor


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As the level rises the fluid

affects the sensor field.

Capacitive sensor


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Until the sensor switches.

Capacitive sensor


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Sensor symbols


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+ 18 to 30 Volts

DC.

0 V

Output

Inductive

Capacitive

Optical

Magnetic

Ultrasonic

Normally

open

Normally

closed

Sensor symbols


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+ 18 to 30 Volts

DC.

0 V

Capacitive Sensor with

Normally open function

Output

Sensor symbols


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Sensor connection


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+ 18 to 30 Volts DC

0 V

Output

24v

DC

0v

PNP Type

Output is Positive

Positive switching

Sensor connection


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NPN Type

Output switches

through to 0v

Negative switching

+ 18 to 30 Volts DC

0 V

Output

24v

DC

0v

Sensor connection


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Sensor connection


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+ 18 to 30 Volts

DC.

0 V

Output

Inductive

Capacitive

Optical

Magnetic

Ultrasonic

Normally

open

Normally

closed

Sensor connection


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Will detect any conductive material

Quoted distances are for mild steel

Sensor performance can be affected by:-

Temperature

Target material

Target dimensions.

ON

OF

F

Targe

t

Sensor

Oscillation

Amplitude

Sensor

output

signal

Inductive sensor


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Detects any material denser than air.

(as long as there is enough of it)

Can be adjusted for sensitivity

Can be affected by dusty environments

Capacitive sensor


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Target

Type: Through-beam

Long sensing distance : up to 30 metres

with some devices

Will detect all but very transparentmaterials

Must be accurately aligned


Optical sensors


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Transmitter/ Receiver Reflector

(prismatic)

Type: Retro-reflective

Sensing distance : 1/2 to1/3 of through-

beam type.

Not suitable for reflective or transparenttargets

Target should be larger

than the reflectorT

R

Optical sensors


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Transmitter/

Receiver

Type : Diffuse

Sensing distance : much less than reflex

type, actual distance depends on colour

and reflective nature of the surface

Larger targets result in longer sensing

distances

Not suitable for dirty

environmentsT

R

Optical sensors


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Interference from other

magnetic fields must be

avoided.

If positioned in mid stroke,

switching point will vary

depending on direction of

approach.

Maximum current must be

limited to avoid burning of the

reed contacts.

Reed switch


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Inductive principle of operation - but

only reacts to magnetic fields

Interference from other magnetic

fields must be avoided

Solid state device - higher switching

frequency - 1kHz


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Sensors (Festo )