PROXIMITY SENSORS report the LOCATION of an important item that must be monitored. Whether the DOOR is open or closed, the FLOW on or off, the LEVEL

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1 Position Sensors

2 PROXIMITY SENSORS report the LOCATION of an important item that must be monitored. Whether the DOOR is open or closed, the FLOW on or off, the LEVEL rising or falling, or the PISTON at the end of its stroke, a proximity sensor can report the status

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4 Styles Electromechanical Electromagnetic Reluctive Ionizing Piezoelectric Solar cell

5 Styles Photoconductive Resistive Inductive Capacitive Photoelectrical

6 Resistive Very simple in construction A switch ON OFF Potentiometer VARIABLE RESISTANCE OVER A GIVEN RANGE

7 Proximity Switches Inductive Sensing Capacitive Sensing

8 Inductive Machine Control

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10 Inductive Nominal Sensing Range And Factors which affect it

11 Inductive Composed of a coil and a ferrite core. Together, these two components form the inductive portion of a LC tuned circuit which drives an oscillator.

12 Inductive Coil Ferrite Core

13 Inductive Eddy Currents

14 Inductive At some precise point, the eddy currents are so large the amplifier cannot output sufficient energy.

15 Inductive Oscillation stops and the field collapses. This is called eddy current killed oscillator.

16 Inductive Turn On Turn Off The difference between turn-on and turn-off, or hysteresis, provides stable operation by preventing the switch from chattering between states.

17 Inductive Sensing range is greatly determined by the size of the switch.

18 Inductive Select switch so the activating device works between the 50% - 80% of its range

19 Inductive When testing, a mild steel is used

20 Inductive Sensing Range Typical Correction Factors Mild Steel 1.0 Stainless Steel Aluminum 0.4 Copper..0.2

21 Inductive Size does matter

22 Inductive Flush versus Non-flush Non-Flush Flush Shield

23 Inductive

24 Inductive Non-flush 1 Diameter Non-flush 2 Diameters Metal Free Zone

25 Non-flush 3 Diameters Metal Free Zone

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27 NONFLUSH MOUNTABLE Longer Range in Same Size Best for most Applications Flush Mountable Tolerates metal in mounting area Less prone to damage Better for small targets Better repeatability

28 Speed Response

29 1 Max Switching rate = Cycle time Based on when target present time = target absent time

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33 Can be up to 30 times as fast as AC of the same size. Flush operates faster then non-flush Smaller switches are faster Input device must be as fast as sensor.

34 Inductive DC or AC

35 DC cheaper Less expense to hook up Faster AC has 2 wire hook-ups DC has 2 or 3 wire hook-ups

36 2 WIRE Cost less Less cost to install Non-polarity specific Act simply like a switch

37 Direct hook up to PLC Voltage drop when activated Make sure the leakage current through the sensor will not trip the load.

38 3 WIRE Polarity Sensitive Cost more Must have external power supply other than the PLC s Lower voltage drop when activated

39 Must specify positive or negative switching - +

40 Capacitive Capacitive sensors detect targets in just the opposite manner as inductive sensors. As a target approaches a capacitive sensor, the oscillations increase until they reach a threshold level and activate a switching device.

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43 Capacitive sensors can Sense conductors Sense non-conductors

44 Cost more than inductive sensors normally False signals might occur from cutting fluids, moisture, dirt build-up.

45 Work great for product detection Level sensing sight glass installs too!

46 Adjusting Capacitive Sensors Mount and fill sensor in vessel. Drain to point that moisture and residue are left on the sensor. If LED id ON turn the sensitivity until the LED just goes OFF If LED is OFF turn it on then back off until it turns OFF. Raise level of tank again

47 Carefully turn off the LED using the sensitivity, counting the number of turns. Turn it back again the opposite direction ½ the number of turns you just counted. This sets it for the midpoint of the range for maximum stability.

48 Remember Don t use to replace inductive switches Nonmetallic targets Level Detection Look-through sensing

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