Contents

4.1

CapacitiveSensors

4

– Non-contact– Wear-free– Non-mutually interfering– Bounce-free output signal– LED function display– Senses virtually any material– Detects objects through many

other non-metallic barriers

Capacitive sensorsdetect the change incapacitance caused bythe approach of anobject. Their advantagelies in the abilityto detect virtually anymaterial, from metalsto oils.

4.2 Definitions, principles,effect of materialscharacteristics

4.3 Function description4.4 Applications4.5 DC ∅ 10 mm, M124.6 DC M184.7 DC M30, ∅ 20 mm,

∅ 34 mm4.8 AC M30, ∅ 20 mm,

∅ 34 mm

A capacitor ... in its traditional form con-sists of two electrode platesand a dielectric, with anon- or poorly conductingmedium in between.Capacitance C = εεεεε (A/d) isdetermined by surface A,

distance d, andthe dielectric constantε ε ε ε ε = (εεεεε0 × εεεεεr).εεεεε describes the dielectric

constant of this medium.

εεεεε0 is the absolut dielectricconstant of empty space(vacuum).

εεεεεr is the dielectric number,a (density dependent)material constant.

... and its effect can beexplained using a step-by-step derivation of itsgeometric shape. The strayfields at the edges of theplates can be ignored forthese purposes.In the middle between twocircular capacitor plates A1

and A2 there is at distance

The sensor electrode

In capacitive sensors ... this "open" capacitor isused as a sensor element.The plate A2 however is con-figured as a ring electrode(housing) concentric to A1 inorder to make the electricalfield symmetrical, and the"intermediate electrode" isthe "actuation element".The "active surface" of thissensor element correspondsto ring electrode A2.

Non-conducting materials ... (plastics, glass as wellas liquids) can be detectedby capacitive sensors, if εr issignificantly greater than ε0;the preceding is based onthe fact that for the lines offield, the path of leastresistance leads across theactuation element.

Since the rated switchingdistance sn is based on agrounded standard targetmade of Fe 360, theswitching distances must becorrected when using othermaterials. Correction factorsfor typical materials are listedin the adjacent table:

If an electrically non-conducting actuationelement (target) enters thesensor field, the capacitancechanges proportionally to εr

and to the immersion depthresp. to the distance to the"active surface". However itnever becomes greater thanfor metals.

Conditions and correctionfactors

Definitions, Principles,Effect of Materials

actuation element

active surface

4.2

CapacitiveSensors

Material Correction factormetals 1.0wood 0.2...0.7glass 0.5water 1.0PVC 0.6oil 0.1

d/2 an additional, goodconducting, folded "inter-mediate electrode" Z withthickness D → 0. An appliedvoltage between A1 and A2

generates an electrical field.This impresses voltage U/2in electrode Z. The "inter-mediate electrode" therebyassumes the function of anadditional capacitor plate.This has the effect of chan-ging the capacitor into twogeometrically and electricallyseries connected capacitors.If these partial capacitors areunfolded, plates A1 and A2 lie

next to each other on onelevel and the "intermediatecapacitor" Z on a secondlevel at distance d/2. Theresult is an "open" capacitor.The fields in the capacitorhalves run in oppositedirections.

The formula for capacitanceremains – with the abovedefined premises – valideven for this capacitorgeometry.

Capacitance C as afunction of the distance stilldecreases hyperbolically (as1/d).

If the actuation element(d → ∞; εr = 1, C → 0) isabsent, they run in an arcfrom the middle to the ringelectrode. The path of leastresistance is thereby alsopartially determined by therepelling effect of identicallyoriented lines of field.

The arcs and their distancesbecome greater from insideto outside.

Function groups

Active surface

Standard target

Usefuloperating distance su

Assuredoperating distance sa

Advantages

Application examples

Function diagnostics

... of a capacitive sensor are:

sensor fieldand electrode

oscillator demodulator trigger outputdriver

It is primarily determined bythe front surface area of thecap and correspondsapproximately to the surfacearea of the outer sensorelectrode.

... is the area through whichthe high-frequency sensorfield enters the air space.

"active surface"

sens

or fi

eld

stan

dard

targ

et

... is a grounded, squareplate made of Fe 360(ISO 630), with the switchingdistance determined perEN 60947-5-2.Thickness is d = 1 mm;

and the side length acorresponds to– the diameter of the

inscribed circle of theactive surface or

– 3 sn, if the value is largerthan the correspondingdiameter

– non-contact– rugged construction– noise-immune

Level monitoring of– liquids– powdered and granular

materials.

Detecting and countingparts made of– metals– plastics– glass.

Function Description

Proximity switches withfunction diagnostics allowvirtually complete monitoringof all sensor functions in-cluding the cable connections.

Here Balluff offers theBES 113-FD-1 self diagnosisunit, which can be easilyintegrated in a controller.

Material comparison inconstant dielectrics.

4.3

CapacitiveSensors

4

... is the permissibleswitching distance of anindividual proximity switchwithin the specified voltage

and temperature ranges(0.72 sn ≤ su ≤ 1.325 sn).

... is the switching distanceat which assured operationof the proximity switch isguaranteed at specified

voltage and temperatureconditions (0 ≤ sa ≤ 0.72 sn).

activ

esu

rfac

e

su

sa

72 % 0 %100 %

132 %

The unit and its function isdescribed on page 1.5.22.

Applications

4.4

CapacitiveSensors

Sensing and thickness detectionof wood in secondary processing.

*No metal permitted underneath the desired object within the sensor field.

Packaging.Are all the ampules there?*

Capacitive sensors

Capacitive sensors detectthe change in capacitanceof an object when it entersthe sensor's electrical field.

This means a capacitivesensor can detect not onlymetal, but even non-conductors whose dielectricconstants are sufficientlylarge.

Properly selected, acapacitive sensor is alsoable to "see through" certainnon-metallic materials.This makes it the classicallevel detector, sensing thepresence or absence ofliquids or granular materialthrough the container wall.

Balluff also offers theappropriate cover nutswhich, once installedin the container, allow thecapacitive sensor to bemounted and later replacedif necessary without un-sealing the vessel.

Inspecting paper, cloth or plasticstrips. From above or below.*

Detecting, counting objects. Inflow or pumping control in waterstorage containers.

Quality and presence sensing incigarette factory. Filter/tobaccook?*

Inspection on packaging lines.Packaging, contents.

Level control in filling applications,controlling the reject station.

Checking for missing labels onthin backing.*

Guiding a knife through metalthread, e.g. for separating cloth.

Level control in plastic or glasscontainers.

Most capacitive sensorsare not designed for flushmounting in metal.

However, the potentiometerson Balluff sensors allow theswitching distance to beadjusted so that even flushmounting is possible.

4.5

CapacitiveSensors

Housing sizeMountingEffective operating distance sr

Assured operating distance sa

Normally-open 1

Rated operational voltage Ue

Supply voltage UB

Voltage drop Ud at leRated insultion voltage Ui

Rated operational current IeMinimum operational current ImNo-load supply current I0 max.Off-state current IrProtected against polarity reversalShort circuit protectedLoad capacity

Repeat accuracy RAmbient temperature range Ta

Frequency of operating cycles fUtilization categoryFunction indication

Degree of protection per IEC 60529

Housing materialMaterial of sensing faceConnectionNo. of wires × conductor cross section

Recommended connector

1 Wiring diagrams see page 1.0.12

Please add the cable length to orderingcode for sensors with cable!PU-03, PU-05 = PUR, length 3 m or 5 m

M12×1non-flush0...8 mm

0...5.8 mm

BCS 012-PS-1-L-S 4

24 V DC10...30 V DC

≤ 1 V75 V DC200 mA0 mA

≤ 10 mA≤ 0.8 µA

yesyes

≤ 1 µF

≤ 5 %–30...+70 °C

100 HzDC 13

yes

IP 65

CuZnPTFE

connector

BKS-B 19/BKS-B 20

M12×1flush

0...4 mm0...2.9 mm

BCS 012-PSB-1-L-S 4

24 V DC10...30 V DC

≤ 1 V75 V DC200 mA0 mA

≤ 10 mA≤ 0.8 µA

yesyes

≤ 1 µF

≤ 5 %–30...+70 °C

100 HzDC 13

yes

IP 65

CuZnPTFE

connector

BKS-B 19/BKS-B 20

∅ 10 mmflush

0...4 mm0...2.9 mm

BCS 010-PSB-1-L-

24 V DC10...30 V DC

≤ 1 V75 V DC200 mA0 mA

≤ 10 mA≤ 0.8 µA

yesyes

≤ 1 µF

≤ 5 %–30...+70 °C

100 HzDC 13

yes

IP 65

stainless steelPTFEcable

3 × 0.14 mm²

DC 3-Wire∅ 10 mm, M12sr 0...4 mm, 0...8 mm

PNP

4

6Connectors,clamps ...page 6.2 ...

4.6

CapacitiveSensors

DC 3-WireM18sr 1...10 mm

M18×1non-flush

1...10 mm0.8...8.1 mm

BCS 018-PS-1-C-BCS 018-PO-1-C-

BCS 018-NS-1-C-BCS 018-NO-1-C-

24 V DC10...30 V DC

≤ 3.5 V250 V AC250 mA100 µA≤ 8 mA≤ 50 µA

yesyes

≤ 1 µF

≤ 5 %–25...+70 °C

≤ 200 HzDC 13

yes

IP 67[

PBTPBTcable

3 × 0.34 mm²

M18×1non-flush

1...10 mm0.8...8.1 mm

BCS 018-PS-1-C-S 4

24 V DC10...30 V DC

≤ 3.5 V75 V DC250 mA100 µA≤ 8 mA≤ 50 µA

yesyes

≤ 1 µF

≤ 5 %–25...+70 °C

≤ 200 HzDC 13

yes

IP 67

PBTPBT

connector

BKS-B 19/BKS-B 20

1 Wiring diagrams see page 1.0.12

Protective cap nuts for installingin containers for level detectionMaterial: PTFEPressure rated up to 13 bar whencorrectly installed.

BES 18-SM-3

BES 30-SM-3

250 mA

175 mA

+70 °C+20 °C–25 °C

Current reduction as a functionof ambient temperature

Housing sizeMountingEffective operating distance sr

Assured operating distance sa

Normally-open 1

Normally-closed 2

Complementary 3

Normally-open 4

Normally-closed 5

Rated operational voltage Ue

Supply voltage UB

Voltage drop Ud at leRated insultion voltage Ui

Rated operational current IeMinimum operational current ImNo-load supply current I0 max.Off-state current IrProtected against polarity reversalShort circuit protectedLoad capacity

Repeat accuracy RAmbient temperature range Ta

Frequency of operating cycles fUtilization categoryFunction indication

Degree of protection per IEC 60529Insulation classHousing materialMaterial of sensing faceConnectionNo. of wires × conductor cross section

Recommended connector

Please add the cable length to orderingcode for sensors with cable!03, 05 = PVC, length 3 m or 5 mPU-03, PU-05 = PUR, length 3 m or 5 m

PNP

NPN

4.7

CapacitiveSensors

DC 3-/4-WireM30, ∅ 20 mm, ∅ 34 mmsr 2...20, 1...12, 3...40 mm

M30×1.5non-flush

2...20 mm1.6...16.2 mm

BCS 030-PS-1-C-BCS 030-PO-1-C-

BCS 030-NS-1-C-BCS 030-NO-1-C-

24 V DC10...30 V DC

≤ 3.5 V250 V AC250 mA100 µA≤ 8 mA≤ 50 µA

yesyes

≤ 1 µF

≤ 10 %–25...+70 °C

≤ 100 HzDC 13

yes

IP 67[

PBTPBTcable

3 × 0.34 mm²

M30×1.5non-flush

2...20 mm1.6...16.2 mm

BCS 030-PS-1-C-S 4

BCS 030-GA-1-C-S 4

24 V DC10...30 V DC

≤ 3.5 V75 V DC250 mA100 µA≤ 8 mA≤ 50 µA

yesyes

≤ 1 µF

≤ 10 %–25...+70 °C

≤ 100 HzDC 13

yes

IP 67

PBTPBT

connector

BKS-B 19/BKS-B 20

additional LEDfor supply voltage

4

Connectors,clamps ...page 6.2 ...

6

∅ 20 mmnon-flush

1...12 mm0.8...9.7 mm

BCS 020-PS-1-C-S 4

BCS 020-NS-1-C-S 4

10...30 V DC30 V DC≤ 3.5 V

250 V AC250 mA≤ 0,1 mA≤ 11 mA≤ 10 µA

yesyes

≤ 0.33 µF

≤ 10 %–25...+70 °C

150 HzDC 13

yes

IP 67[

PBTPBT

connector

BKS-B 19/BKS-B 20Clamp cuff included!

∅ 20 mmnon-flush

1...12 mm0.8...9.7 mm

BCS 020-PS-1-C-

BCS 020-NS-1-C-

10...30 V DC30 V DC≤ 3.5 V

250 V AC250 mA≤ 0,1 mA≤ 11 mA≤ 10 µA

yesyes

≤ 0.33 µF

≤ 10 %–25...+70 °C

150 HzDC 13

yes

IP 67[

PBTPBTcable

3 × 0.34 mm²

Clamp cuff included!

∅∅∅∅∅ 34 mmnon-flush

3...40 mm2.4...32.4 mm

BCS 034-PS-1-C-BCS 034-PO-1-C-

BCS 034-NS-1-C-BCS 034-NO-1-C-

24 V DC10...30 V DC

≤ 3.5 V250 V AC250 mA100 µA≤ 8 mA≤ 50 µA

yesyes

≤ 1 µF

≤ 10 %–25...+70 °C

≤ 100 HzDC 13

yes

IP 67[

PBTPBTcable

3 × 0.34 mm²

Clamp cuff included!

4.8

CapacitiveSensors

AC 2-WireM18, M30, ∅ 34 mmsr 1...10 mm, 2...20 mm, 3...40 mm

M18×1non-flush

1...10 mm0.8...8.1 mm

BCS 018-WS-5-L-BCS 018-WO-5-L-

110 V AC45...250 V AC

≤ 21 V250 V AC250 mA8 mA

≤ 3 mA≤ 2 A/≤ 1 Hz

yesno

≤ 5 %–25...+70 °C

25 HzAC 140

yes

IP 67[

PBTPBTcable

2 × 0.34 mm²

M30×1.5non-flush

2...20 mm1.6...16.2 mm

BCS 030-WS-5-L-BCS 030-WO-5-L-

110 V AC45...250 V AC

≤ 21 V250 V AC250 mA8 mA

≤ 3 mA≤ 2 A/≤ 1 Hz

yesno

≤ 10 %–25...+70 °C

25 HzAC 140

yes

IP 67[

PBTPBTcable

2 × 0.34 mm²

Housing sizeMountingEffective operating distance sr

Assured operating distance sa

Normally-open !

Normally-closed "

Rated operational voltage Ue

Supply voltage UB

Voltage drop Ud at leRated insultion voltage Ui

Rated operational current IeMinimum operational current ImOff-state current IrInrush current Ik t ≤ 20 msProtected against polarity reversalShort circuit protected

Repeat accuracy RAmbient temperature range Ta

Frequency of operating cycles fUtilization categoryFunction indication

Degree of protection per IEC 60529Insulation classHousing materialMaterial of sensing faceConnectionNo. of wires × conductor cross section

AC

! Wiring diagrams see page 1.0.12

Please add the cable length to orderingcode for sensors with cable!03 = PVC, length 3 m

∅∅∅∅∅ 34 mmnon-flush

3...40 mm2.4...32.4 mm

BCS 034-WS-5-L-BCS 034-WO-5-L-

110 V AC45...250 V AC

≤ 21 V250 V AC250 mA8 mA

≤ 3 mA≤ 2 A/≤ 1 Hz

yesno

≤10 %–25...+70 °C

25 HzAC 140

yes

IP 67[

PBTPBTcable

2 × 0.34 mm²

Clamp cuff included!