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Switches and sensors
1. Switches and Sensors
For integrated control systems
Presemtatiom By Waqar Aziz
waqaraziz370@gmail.com
2. Contents
Introduction
Magnetic cylinders
Reed switch principle
Sensor principle
QM/45/* range
QM/33,34,134 range
M/40,41,42 range
Inductive proximity
sensors
Cable capacitance
Vacuum electric switch
Vacuum electronic switch
Click the section to advance directly to it
3. Introduction
Typical electro-pneumatic systems
consist of:
magnetic cylinders and solenoid
valves for dynamic power
reed switches and sensors for
feedback
electronic logic for control
Reed switches and solid state
magnetic sensors are fitted to
cylinders to feedback particular
positions of the piston
Solid state proximity sensors can be
used to replace limit switches, for
detecting the position of
mechanisms or other moving parts
Reed switches and solid state
sensors are small, fast, easy to fit
and adjust. They simplify
installation on to the machine
application
4. Magnetic cylinders
Magnetic cylinders have a band of magnetic material inset around the circumference
of the piston
The polarity is in parallel with the axis of the cylinder
The barrel is made of non ferrous material
By placing reed switches along the outside of the cylinder, signals can be given at the
extreme and intermediate positions of stroke
Click the illustration to start and stop animation
5. Reed switch principle
A basic reed switch consists of a small glass tube containing soft iron contact
reeds normally sprung open
When a magnetic field is in range the reeds will become magnetic
The ends will be of opposite polarity and pull themselves together
Click the illustration to start and stop animation
6. Magnetic sensor principle
In the presence of a magnetic field the magnetoresistive sensor has a lower
resistance. This causes current to be drawn from the base of the transistor
turning it on
The circuit incorporates l.e.d., reverse polarity protection diodes and
suppression diode for an inductive load
+V
load
sensor
N
S
0V
7. Reed switches and sensor
Slim cylindrical housing
PVC cable in 2 or 5 metre lengths
Optional very flexible polyurethane cable
With or without l.e.d. indicator
Range of four reed switches and one solid state sensor
8. Reed switches
Basic reed switch
Shown connected to a relay or solenoid coil with diode suppression for d.c.
application
10 to 30V a.c./d.c.
Maximum switching power 10 W/VA
Protection diode
for d.c. only
QM/45/RAP
0V
Blue
Brown
Coil
+V
9. Reed switches
Reed switch with l.e.d. indicator
Three wires emulating p.n.p. sensor
Current sourced on the black wire to the coil
Resistor protects l.e.d. from over voltage
Protection diode
QM/45/LAP
0V
Black
Coil
Blue
0V
Brown
+V
10. Reed switches
Reed switch with l.e.d. indicator and two wires only
Current sourced on the black wire to the coil
Zener diode provides small voltage drop to turn on l.e.d.
10 to 240V a.c./170V d.c. 10 W/VA maximum
Shown with VDR for suppression a.c. or d.c.
QM/45/LAP
Voltage dependant
resistor (VDR)
0V
Blue
Brown
Coil
+V
11. Reed switches
Reed switch with l.e.d. indicator
Three wires emulating n.p.n. sensor
Current sunk on the blue wire from the load to 0V
Resistor protects l.e.d. from over voltage
Protection diode
+V
QM/45/LAN
Black
Load
Brown
+V
Blue
0V
12. Solid state switches
Solid state magnetically operated p.n.p. output
Used for applications where vibration levels are unsuitable for reed switches
Magnetoresistive sensor element
‘Sensor on’ l.e.d. indicator
10 to 30 V d.c. 200mA maximum
QM/45/EAP
brown
+V
blue
0V
coil
pnp
black
protection diode
0V
13. Reed switches and sensors
Neat cylindrical housing with fixed or plug-in cable
Straight or 90o plug-in connector cables
Optional: very flexible polyurethane cable or
high temperature (150oC) silicon cable
With or without l.e.d. indicator
Wide range of reed switches and solid state sensors
14. Reed switches
Plain reed switch
brown +V
QM/33
Plain change-over reed switch
Three wire reed switch with l.e.d.,
emulating p.n.p. sensor and plug-in
cable
Three wire reed switch with l.e.d.,
emulating n.p.n. sensor
Two wire reed switch with l.e.d.
Load
blue
QM/33/C
black
blue
0V
Load
Load
0V
0V
brown +V
QM/34/P
QM/34/N
brown +V
blue 0V
Load
black
0V
blue 0V
brown +V
Load
black
+V
brown +V
QM/34/S
blue
Load
0V
15. Solid state sensors
Output p.n.p. fixed cable
Output p.n.p. plug-in cable
QM/134
pnp
Output n.p.n. fixed cable
Output n.p.n. plug-in cable
brown +V
blue 0V
black
1
3
QM/134/P
pnp
4
QM/134/N
black
npn
black
QM/134/X
0V
4
Load
+V
blue 0V
brown +V
3
npn
Load
blue 0V
brown +V
1
QM/134/N/P
0V
brown +V
blue 0V
Pulse stretcher. Output p.n.p. fixed
cable. When operated and released
output will remain on for a further
30 ms approximately. Suitable for
part stroke position on fast
operating cylinders
Load
black
Load
+V
brown +V
blue 0V
black
Load
0V
16. Reed switches and sensors
Low profile with dove tail slide for cylinders with integral track in extruded
body
Screw tightening
Fixed cable or plug-in connector cables straight or 90o
With or without l.e.d.
17. Reed switches and sensors
Low profile with dove tail slide for cylinders with integral track in extruded
body
Screw tightening
Fixed cable or plug-in connector cables straight or 90o
With or without l.e.d.
18. Reed switches
brown
+V
Two wire with l.e.d. 10 to 240V
a.c./170V d.c.
With high temperature cable
With very flexible polyurethane
cable
Two wire with l.e.d. and plug in
cable 10 to 60V a.c./74 d.c.
Change-over contacts without l.e.d.
M/40
blue
TM/40
Load
0V
M/40/*/PU
brown
+V
M/40/P
Load
M/40/C
black
blue
brown
Load
Load
0V
blue
0V
0V
+V
19. Solid state magnetic switches
Output n.p.n. 10 to 30V d.c. 200
mA maximum
Output p.n.p. 10 to 30V d.c. 200
mA maximum
Output p.n.p. with very flexible
polyurethane cable
Output p.n.p. with plug-in cable
M/41
M/42
blue 0V
brown +V
npn
black
pnp
black
1
3
pnp
+V
brown +V
blue 0V
M/42/*/PU
M/42/P
Load
4
Load
0V
brown +V
blue 0V
black
Load
0V
20. Inductive proximity sensors
Sense the presence of metal near the
M/P28473
tip
Used as a limit switch for
mechanical parts
Depending on type:
M/P70104/1&2
Range 0.8 to 2 mm
M/P70104/3&4
Switching frequency 500 to 2000 Hz
With or without l.e.d.
M/P70104/5&6
10 to 30 or 6 to 30 V d.c.
Normally closed or normally open
M/P70104/7&8
p.n.p. output
M/P70104/9
brown
pnp
+V
blue
black
Load
0V
brown
pnp
+V
blue
black
Load
0V
21. Cable capacitance
Long leads above the standard cable length become a long thin capacitor
+V
(equivalent circuit
)
0V
Closing the switch shorts the capacitor, the instant high current overloads and
damages the switch contacts
Fit an inductor (470µH) close to the switch. This damps the surge but has a low
steady state resistance
+V
0V
L
470µH
+V
Load
Standard leads
Extended leads
0V
22. Vacuum electric switch
Switches contacts at a vacuum set
point
Adjustable between zero and 0.8 bar
absolute
Normally open and normally closed
versions
Up to 250V a.c./d.c. 2A max
Repeatability + or - 0.1 bar
Reset differential 0.2 bar
23. Vacuum solid state switch
Analogue output 1 to 5 V
proportional to vacuum
Solid state switched output at
vacuum set point
Adjustable reset hysteresis
Adjustable from zero to 1bar
absolute
Output n.p.n. or p.n.p. vesions
set point
hysteresis
U
+V dc supply (brown)
Analog out (white)
Switch out (black)
Load
0 V (blue)
U
+V dc supply (brown)
Analog out (white)
Switch out (black)
Load
0 V (blue)