EAO_MC_18_Main-Catalogue_EN

HMI Components

Edition 07/2012

Series

18

Characteristics

Functions

Market segments

The compact 8 mm Series 18 is especially suited for:

The Series 18 incorporates the following functions:

The EAO Series 18 is especially suited for applications in the segments:

■■ ■■ ■■

Flush design Raised design PCB (with adaptor)

■■ ■■ ■■

Indicator Pushbutton Illuminated pushbutton

■■ ■■

Audio and video Laboratory and measuring equipment

The low level switching element is laid out for low current applications.

Please refer to the EAO website to obtain detailed information regarding this series www.products.eao.com Configure a product to your exact needs and request a quotation.

Content

18 01

Overview

02

Flush design Indicator

320

Pushbutton

322

Illuminated pushbutton

323

04

Indicator

324

10

Pushbutton

326

Illuminated pushbutton

328

Raised design

Accessories

330

Drawings

336

Technical data

337

Application guidelines

338

03

14 17 18 19 22 31 41 44 51 56 57 61 70 71 82 84 92 95 96 97 99 ST

319

18 01

Flush design

Indicator, IP 40

02

Equipment consisting of (schematic overview)

4 max.

03

Lens 18

04 10

Actuator 1

14 17

Product can differ from the current configuration.

30.5

Dimensions [mm]

Additional Information

• Luminosity and wave length variations caused by LED manufacturing processes may cause slight differences regarding the illumination

3 NBY

22

41

Âą

Each Part Number listed below includes all the black components shown in the 3D-drawing.

To obtain a complete unit, please select the red components from the pages shown.

Mounting cut-outs [mm]

Lens

Terminal

Part No.

Component layout

Wiring diagram

44

Weight

Plastic red translucent

Solder

18-080.0052

1

1

0.002 kg

Plastic yellow translucent

Solder

18-080.0054

1

1

0.002 kg

Plastic green translucent

Solder

18-080.0055

1

1

0.002 kg

Plastic red translucent

Solder

18-081.0052

1

1

0.003 kg

Plastic yellow translucent

Solder

18-081.0054

1

1

0.003 kg

Plastic green translucent

Solder

18-081.0055

1

1

0.003 kg

Plastic red translucent

Solder

18-082.0052

1

1

0.003 kg

Plastic yellow translucent

Solder

18-082.0054

1

1

0.003 kg

Plastic green translucent

Solder

18-082.0055

1

1

0.003 kg

51 56

Forward voltage typ.

57 61

Operating voltage

Operation current

Indicator actuator

2.2 VDC @ 20 mA

70

12 VDC

20 mA

71 82

24 VDC

84 92 95 96 97 99 ST

320

page 332

Fixing nut

31

Front bezel set

NJO Âą NN

NJO

19

NJO Y NN

• For front dimensions 19 x 19 mm, Ă˜ 19mm

18

20 mA

Operating voltage

Operation current

Lens

Terminal

Part No.

Wiring diagram

Forward voltage typ.

Component layout

Flush design

18 01 Weight

02 03

Indicator actuator

2.2 VDC @ 20 mA

12 VDC

24 VDC

20 mA

20 mA

Plastic red translucent

Solder

18-060.0052

1

1

0.002 kg

Plastic yellow translucent

Solder

18-060.0054

1

1

0.002 kg

Plastic green translucent

Solder

18-060.0055

1

1

0.002 kg

Plastic red translucent

Solder

18-061.0052

1

1

0.003 kg

Plastic yellow translucent

Solder

18-061.0054

1

1

0.003 kg

Plastic green translucent

Solder

18-061.0055

1

1

0.003 kg

Plastic red translucent

Solder

18-062.0052

1

1

0.003 kg

Plastic yellow translucent

Solder

18-062.0054

1

1

0.003 kg

Plastic green translucent

Solder

18-062.0055

1

1

0.003 kg

04 10 14 17 18 19

The component layouts you will find from page 336

22 31 41 44

Wiring diagram 1

51 56 57 61 70 71 82 84 92 95 96 97 99 ST

321

18 01

Flush design

Pushbutton, IP 40

02

Equipment consisting of (schematic overview)

4 max.

03

Lens 18

1

04 10 1

14 Additional Information

NJO Y NN

• For front dimensions 19 x 19 mm, Ă˜ 19mm

NJO Âą NN

Front bezel set

page 332

• +/- terminals are not connected NJO

19

Dimensions [mm]

3 NBY

18

Actuator

30.5

17

Product can differ from the current configuration.

page 330

22

Fixing nut

31 41

Âą

Each Part Number listed below includes all the black components shown in the 3D-drawing.

To obtain a complete unit, please select the red components from the pages shown.

Mounting cut-outs [mm]

Switching action

Terminal

Part No.

Component layout

Wiring diagram

44 Weight

1 NC

B

Solder

18-188.035

2

1

0.002 kg

C

Solder

18-288.035

2

2

0.002 kg

1 NO

B

Solder

18-187.035

2

3

0.002 kg

C

Solder

18-287.035

2

4

0.002 kg

1 NC

B

Solder

18-168.035

2

1

0.002 kg

C

Solder

18-268.035

2

2

0.002 kg

1 NO

B

Solder

18-167.035

2

3

0.002 kg

C

Solder

18-267.035

2

4

0.002 kg

51 56

Switching system

Contacts

57 61

Pushbutton actuator

Snap-action switching element

70 71 82 84

92 95 96

Pushbutton actuator

Snap-action switching element

Contacts: NC = Normally closed, NO = Normally open Switching action: B = Momentary, C = Maintain The component layouts you will find from page 336

97

2

2

4

4

1

1

1

1

99 ST

Wiring diagram 1

322

Wiring diagram 2

Wiring diagram 3

Wiring diagram 4

Flush design

18 01

Illuminated pushbutton, IP 40

Equipment consisting of (schematic overview)

Lens

02

4 max.

03

page 330 1

18

04 10

Actuator

1

30.5

14

Dimensions [mm]

Product can differ from the current configuration.

17

Additional Information page 332

NJO Y NN

NJO Âą NN

3 NBY

Fixing nut

19 22

Each Part Number listed below includes all the black components shown in the 3D-drawing.

To obtain a complete unit, please select the red components from the pages shown.

18

• For front dimensions 19 x 19 mm, Ă˜ 19mm

NJO

Front bezel set

Âą

31 41

Mounting cut-outs [mm]

Contacts

Switching action

Terminal

Part No.

Wiring diagram

Switching system

Component layout

44 51 Weight

56 57

Illuminated pushbutton actuator

Snap-action switching element

1 NC

1 NO

B

Solder

18-188.035

2

1

0.002 kg

C

Solder

18-288.035

2

2

0.002 kg

B

Solder

18-187.035

2

3

0.002 kg

C

Solder

18-287.035

2

4

0.002 kg

61 70 71

82

Illuminated pushbutton actuator

Snap-action switching element

1 NC

1 NO

B

Solder

18-168.035

2

1

0.002 kg

C

Solder

18-268.035

2

2

0.002 kg

B

Solder

18-167.035

2

3

0.002 kg

C

Solder

18-267.035

2

4

0.002 kg

2

92 95

Contacts: NC = Normally closed, NO = Normally open Switching action: B = Momentary, C = Maintain The component layouts you will find from page 336

2

84

96 4

97

4

99 1

Wiring diagram 1

1

Wiring diagram 2

1

Wiring diagram 3

1

ST

Wiring diagram 4

323

18 01

Raised design

Indicator, IP 40

02

Equipment consisting of (schematic overview)

4 max.

03

Lens Ă˜9

04 10

7.2

Actuator

23

14 17

Product can differ from the current configuration.

Dimensions [mm]

Additional Information

19

NJO Y NN

• Luminosity and wave length variations caused by LED manufacturing processes may cause slight differences regarding the illumination

NJO

Each Part Number listed below includes all the black components shown in the 3D-drawing.

Y NN Âą NN

NJO

18

Fixing nut

22

31

Âą

41

Mounting cut-outs [mm]

Forward voltage typ.

Operating voltage

Operation current

Terminal

Part No.

Wiring diagram

51

Component layout

44

Weight

Plastic red translucent

Solder

18-050.0052

1

1

0.002 kg

Plastic yellow translucent

Solder

18-050.0054

1

1

0.002 kg

Lens

56 57

Indicator actuator, Front dimension 9 x 9 mm

2.2 VDC @ 20 mA

61 70

12 VDC

20 mA

71 24 VDC

20 mA

82

Plastic green translucent

Solder

18-050.0055

1

1

0.002 kg

Plastic red translucent

Solder

18-051.0052

1

1

0.002 kg

Plastic yellow translucent

Solder

18-051.0054

1

1

0.002 kg

Plastic green translucent

Solder

18-051.0055

1

1

0.002 kg

Plastic red translucent

Solder

18-052.0052

1

1

0.002 kg

Plastic yellow translucent

Solder

18-052.0054

1

1

0.002 kg

Plastic green translucent

Solder

18-052.0055

1

1

0.002 kg

Plastic red translucent

Solder

18-040.0052

1

1

0.002 kg

Plastic yellow translucent

Solder

18-040.0054

1

1

0.002 kg

Plastic green translucent

Solder

18-040.0055

1

1

0.002 kg

Plastic red translucent

Solder

18-041.0052

1

1

0.002 kg

Plastic yellow translucent

Solder

18-041.0054

1

1

0.002 kg

Plastic green translucent

Solder

18-041.0055

1

1

0.002 kg

Plastic red translucent

Solder

18-042.0052

1

1

0.002 kg

Plastic yellow translucent

Solder

18-042.0054

1

1

0.002 kg

Plastic green translucent

Solder

18-042.0055

1

1

0.002 kg

84 92 95

Indicator actuator, Front dimension 9 x 14 mm

2.2 VDC @ 20 mA

96

12 VDC

20 mA

97 99

24 VDC

ST

324

20 mA

Operating voltage

Operation current

Lens

Terminal

Part No.

Wiring diagram

Forward voltage typ.

Component layout

Raised design

18 01 Weight

02 03

Indicator actuator, Front dimension Ă˜ 9 mm

2.2 VDC @ 20 mA

12 VDC

24 VDC

20 mA

20 mA

Plastic red translucent

Solder

18-030.0052

1

1

0.002 kg

Plastic yellow translucent

Solder

18-030.0054

1

1

0.002 kg

Plastic green translucent

Solder

18-030.0055

1

1

0.002 kg

Plastic red translucent

Solder

18-031.0052

1

1

0.002 kg

Plastic yellow translucent

Solder

18-031.0054

1

1

0.002 kg

Plastic green translucent

Solder

18-031.0055

1

1

0.002 kg

Plastic red translucent

Solder

18-032.0052

1

1

0.002 kg

Plastic yellow translucent

Solder

18-032.0054

1

1

0.002 kg

Plastic green translucent

Solder

18-032.0055

1

1

0.002 kg

04 10 14 17 18 19

The component layouts you will find from page 336

22 31 41 44

Wiring diagram 1

51 56 57 61 70 71 82 84 92 95 96 97 99 ST

325

18 01

Raised design

Pushbutton, IP 40

02

Equipment consisting of (schematic overview)

4 max.

03

Lens Ă˜9

04

page 332

10

8.7

Actuator

23

14 Fixing nut Additional Information

NJO Y NN

• +/- terminals are not connected

NJO

Y NN Âą NN

To obtain a complete unit, please select the red components from the pages shown.

NJO

19 22

Each Part Number listed below includes all the black components shown in the 3D-drawing.

31

Âą

41

Mounting cut-outs [mm]

44 51

Switching system

Contacts

Switching action

Terminal

Part No.

Wiring diagram

18

Dimensions [mm]

Component layout

17

Product can differ from the current configuration.

Weight

56 57

Pushbutton actuator, Front dimension 9 x 9 mm

Snap-action switching element

1 NC

61 1 NO

70

B

Solder

18-158.035

2

1

0.002 kg

C

Solder

18-258.035

2

2

0.002 kg

B

Solder

18-157.035

2

3

0.002 kg

C

Solder

18-257.035

2

4

0.002 kg

71 82

Pushbutton actuator, Front dimension 9 x 14 mm

Snap-action switching element

84

1 NC

1 NO

92

B

Solder

18-148.035

2

1

0.002 kg

C

Solder

18-248.035

2

2

0.002 kg

B

Solder

18-147.035

2

3

0.002 kg

C

Solder

18-247.035

2

4

0.002 kg

95 96

Pushbutton actuator, Front dimension Ă˜ 9 mm

Snap-action switching element

97

1 NC

1 NO

99 ST

Contacts: NC = Normally closed, NO = Normally open Switching action: B = Momentary, C = Maintain The component layouts you will find from page 336

326

B

Solder

18-138.035

2

1

0.002 kg

C

Solder

18-238.035

2

2

0.002 kg

B

Solder

18-137.035

2

3

0.002 kg

C

Solder

18-237.035

2

4

0.002 kg

Raised design 2

2

4

18 01

4

02 1

Wiring diagram 1

1

Wiring diagram 2

1

Wiring diagram 3

03

1

04

Wiring diagram 4

10 14 17 18 19 22 31 41 44 51 56 57 61 70 71 82 84 92 95 96 97 99 ST

327

18 01

Raised design

Illuminated pushbutton, IP 40

02

Equipment consisting of (schematic overview)

4 max.

03

Lens Ă˜9

04

page 332

10

8.7

Actuator

23

14 Dimensions [mm] Fixing nut NJO Y NN

18

NJO

22

Each Part Number listed below includes all the black components shown in the 3D-drawing.

To obtain a complete unit, please select the red components from the pages shown.

NJO

19

Y NN Âą NN

31

Âą

41 44 51

Switching system

Contacts

Switching action

Terminal

Part No.

Wiring diagram

Mounting cut-outs [mm]

Component layout

17

Product can differ from the current configuration.

Weight

56 57 61

Illuminated pushbutton actuator, Front dimension 9 x 9 mm

Snap-action switching element

1 NC

1 NO

70

B

Solder

18-158.035

2

1

0.002 kg

C

Solder

18-258.035

2

2

0.002 kg

B

Solder

18-157.035

2

3

0.002 kg

C

Solder

18-257.035

2

4

0.002 kg

71 82 84

Illuminated pushbutton actuator, Front dimension 9 x 14 mm

Snap-action switching element

1 NC

1 NO

92

B

Solder

18-148.035

2

1

0.002 kg

C

Solder

18-248.035

2

2

0.002 kg

B

Solder

18-147.035

2

3

0.002 kg

C

Solder

18-247.035

2

4

0.002 kg

95 96 97

Illuminated pushbutton actuator, Front dimension Ă˜ 9 mm

Snap-action switching element

1 NC

1 NO

99 ST

Contacts: NC = Normally closed, NO = Normally open Switching action: B = Momentary, C = Maintain The component layouts you will find from page 336

328

B

Solder

18-138.035

2

1

0.002 kg

C

Solder

18-238.035

2

2

0.002 kg

B

Solder

18-137.035

2

3

0.002 kg

C

Solder

18-237.035

2

4

0.002 kg

Raised design 2

2

4

18 01

4

02 1

Wiring diagram 1

1

Wiring diagram 2

1

Wiring diagram 3

03

1

04

Wiring diagram 4

10 14 17 18 19 22 31 41 44 51 56 57 61 70 71 82 84 92 95 96 97 99 ST

329

18

Accessories

01

Front

02

Lens without LED flush design

03 04 10

Dimension

14 17

Lens

Part No.

Weight

Lens without LED flush design

13.8 x 13.8 mm

18 19

Plastic black opaque

18-982.0

0.001 kg

Plastic red translucent

18-982.2

0.001 kg

Plastic yellow translucent

18-982.4

0.001 kg

Plastic green translucent

18-982.5

0.001 kg

Plastic grey opaque

18-982.8

0.001 kg

Plastic white translucent

18-982.9

0.001 kg

18-962.0

0.001 kg

22 31 41

Lens without LED flush design

Ø 13.8 mm

Plastic black opaque

44 51

Plastic red translucent

18-962.2

0.001 kg

Plastic yellow translucent

18-962.4

0.001 kg

Plastic green translucent

18-962.5

0.001 kg

Plastic grey opaque

18-962.8

0.001 kg

Plastic white translucent

18-962.9

0.001 kg

Part No.

Weight

18-981.2

0.001 kg

56 57 61 70 71

Lens with LED flush design Additional Information • Without built-in series resistor, typical forward voltage 2.2 VDC @ 20 mA • Luminosity and wave length variations caused by LED manufacturing processes may cause slight differences regarding the illumination

82 84

Dimension

Lens

92 95

13.8 x 13.8 mm

96

Lens with LED flush design Plastic red translucent Plastic yellow translucent

18-981.4

0.001 kg

Plastic green translucent

18-981.5

0.001 kg

97 99 ST

Ø 13.8 mm

330

Lens with LED flush design Plastic red translucent

18-961.2

0.001 kg

Plastic yellow translucent

18-961.4

0.001 kg

Plastic green translucent

18-961.5

0.001 kg

Accessories

18 01

Lens without LED raised design

02 Dimension

Lens

Part No.

03

Weight

04

7.5 x 7.5 mm

10

Lens without LED raised design Plastic black opaque

18-952.0

0.001 kg

Plastic red translucent

18-952.2

0.001 kg

Plastic yellow translucent

18-952.4

0.001 kg

Plastic green translucent

18-952.5

0.001 kg

Plastic grey opaque

18-952.8

0.001 kg

Plastic white translucent

18-952.9

0.001 kg

14 17 18 19

7.5 x 12.5 mm

22

Lens without LED raised design Plastic black opaque

18-942.0

0.001 kg

Plastic red translucent

18-942.2

0.001 kg

Plastic yellow translucent

18-942.4

0.001 kg

Plastic green translucent

18-942.5

0.001 kg

Plastic grey opaque

18-942.8

0.001 kg

Plastic white translucent

18-942.9

0.001 kg

31 41 44 51

Ă˜ 7.5 mm

56

Lens without LED raised design Plastic black opaque

18-932.0

0.001 kg

Plastic red translucent

18-932.2

0.001 kg

Plastic yellow translucent

18-932.4

0.001 kg

Plastic green translucent

18-932.5

0.001 kg

Plastic grey opaque

18-932.8

0.001 kg

Plastic white translucent

18-932.9

0.001 kg

57 61 70 71 82 84 92 95 96 97 99 ST

331

18 01 02 03 04

Accessories

Lens with LED raised design Additional Information • Without built-in series resistor, typical forward voltage 2.2 VDC @ 20 mA • Luminosity and wave length variations caused by LED manufacturing processes may cause slight differences regarding the illumination

10 14 Dimension

Lens

Part No.

Weight

17 18 19

Lens with LED raised design

7.5 x 7.5 mm

22

Plastic red translucent

18-951.2

0.001 kg

Plastic yellow translucent

18-951.4

0.001 kg

Plastic green translucent

18-951.5

0.001 kg

31 41

Lens with LED raised design

7.5 x 12.5 mm

44

Plastic red translucent

18-941.2

0.001 kg

Plastic yellow translucent

18-941.4

0.001 kg

Plastic green translucent

18-941.5

0.001 kg

Plastic red translucent

18-931.2

0.001 kg

51 56 57

Lens with LED raised design

Ø 7.5 mm

61 70

Plastic yellow translucent

18-931.4

0.001 kg

Plastic green translucent

18-931.5

0.001 kg

Front bezel

Part No.

Weight

18-920.1

0.006 kg

18-920.2

0.006 kg

18-920.3

0.006 kg

Front bezel set

71 82

Product attribute

Mounting cut-out

84 92 95

for square lens

Front bezel set, flush design, Front dimension 19 x 19 mm 15.8 x 15.8 mm

Plastic black

96 97

for round lens

Front bezel set, flush design, Front dimension 19 x 19 mm 15.8 x 15.8 mm

Plastic black

99 ST

for round lens

332

Front bezel set, flush design, Front dimension Ø 19 mm Ø 16 mm

Plastic black

Accessories

18 01

Blind plug

02

Additional Information • The dimensions of the mounting cut-outs are shown in the product details

03 04

Dimension

Mounting cut-out

Material

Colour

Part No.

10

Weight

14

17

Blind plug

9 x 9 mm

Ø 8 mm

Plastic

black

19-948.0

0.001 kg

18 19

Ø 9 mm

Blind plug Ø 8 mm

Plastic

black

19-949.0

22

0.001 kg

31 41 44 51 56 57 61 70 71 82 84 92 95 96 97 99 ST

333

18

Accessories

01

Rear side

02

PCB plug-in base

9.2

03 04

11.7

3.35

8.8

5.6

14 17

8.8

Dimensions [mm]

Terminal

Part No.

Component layout

18

3.2

9.2

10

11.7

Weight

PCB

18-945

3

0.001 kg

PCB

18-946

4

0.001 kg

19 22

Dimension

pins

31 41

PCB plug-in base

8.8 x 9.2 x 11.7 mm

axial

44 51 56

PCB plug-in base

8.8 x 9.2 x 11.7 mm

right-angled

The component layouts you will find from page 336

57 61 70 71 82 84 92 95 96 97 99 ST

334

Accessories

18

Mounting

01

Lens remover

02 03 04

Part No.

Weight

10 14

Lens remover

18-910

17

0.002 kg

18 Mounting tool

19

Additional Information

22

• For fixing nut long Part No. 19-991

31 41 Part No.

Weight

44 51

19-905

Mounting tool

56

0.011 kg

57 61 70 71 82 84 92 95 96 97 99 ST

335

18 01 02

Drawings

Drawings 9 x 9 mm 19 x 19 mm

03

9 x 14 mm

+

Ø9 mm Ø19 x 19 mm

+

9 x 9 mm 19 x 19 mm

+

+ 1

04

9 x 14 mm

+

X

1

10 14 17 Component layout 1

22

2.54

10.16

+ 1

-

2.54

1.6

2.3

9.2

Component layout 3

57 61 70 71 82 84 92 95 96 97 99 ST

336

2.54

Pins for mounting

8.8

8.8

1

44

56

2.54

+

4x Ø 1.1

51

2x Ø 1.1

2.54

31 41

Drilling plan (element side) Through-connection recommended

Drilling plan (element side) Through-connection recommended

2.54

19

Component layout 2

2.54

18

4x Ø 1.1 11.7

Component layout 4

Ø9 mm Ø19 x 19 mm

Pins for contact / LED

X

+ 1

X

X contact-nr.

2 = NO 4 = NC

Technical data

18 01

Actuator with snap-action switching element Switching system

Electrical characteristics

The snap-action switching system was designed for switching low powers in electronic circuits.

Single-break snap-action contact.

Contact resistance ≤ 100 mΩ starting value (initial), as per IEC 60512-2-2b

Material

Electrical life ≥ 500 000 cycles of operation at 30 VDC, 100 mA, as per IEC 60512-5-9c

Lens Polymethylacrylate (PMMA), Polycarbonate (PC)

Power consumption LED 20 mA

Material of contact Gold contact on nickel plating

Switch rating min. 10 μA at 100 μV max. 100 mA at 42 VAC/VDC

Actuator housing Polyamide, colour black

02 03 04 10 14 17 18

Electric strength 500 VAC, 50 Hz, 1 min. between all terminals and earth, as per IEC 60512-2-11

19

Mechanical characteristics Terminals The terminals can be used as soldering terminals.

Max. wire diameter: 2 x 0.5 mm² Max. wire cross-section of stranded cable 1 x 0.75 mm² Wire cross-section of terminal 1.6 x 0.4 mm Tightening torque for fixing nut max. 20 Ncm Actuating force 1.4 N Actuating travel 2.2 mm ±0.2 mm Rebound time ≤ 2.5 ms

22

Environmental conditions

31

Storage temperature -40 °C … +80 °C

41

Service temperature -25 °C … +65 °C

44

Protection degree IP 40 front side, as per IEC 60529

51

Shock resistance (Single impacts, semi-sinusodial) 50 g for 11 ms, as per IEC 60068-2-27

56 57

Vibration resistance (sinusoidal) 10 g at 10 – 2000 Hz, amplitude 0.75 mm, as per IEC 60512-4-4

61 70

Mechanical lifetime Momentary action 2 million cycles of operation Maintained action 1 million cycles of operation, as per IEC 60512-5-9a

71 82 84

EAO reserves the right to alter specifications without further notice.

92 95 96 97 99 ST

337

18 01 02 03 04 10 14 17

Application guidelines

Suppressor circuits When switching inductive loads such as relays, DC motors, and DC solenoids, it is always important to absorb surges (e. g. with a diode) to protect the contacts. When these inductive loads are switched off, a counter emf can severely damage switch contacts and greatly shorten lifetime.

Fig. 1 shows an inductive load with a free-wheeling diode connected in parallel. This free-wheeling diode provides a path for the inductor current to flow when the current is interrupted by the switch. Without this free-wheeling diode, the voltage across the coil will be limited only by dielectric breakdown voltages of the circuit or parasitic elements of the coil. This voltage can be kilovolts in amplitude even when nominal circuit voltages are low (e. g. 12 VDC) see Fig. 2.

18

22

Switch

ON

31 41

To get an efficient protection, the free-wheeling diode must be connected as close as possible to the inductive load!

Counter EMF over load without free-wheeling diode Fig. 2

Switching with inductive load Fig. 1

19

The free-wheeling diode should be chosen so that the reverse breakdown voltage is greater than the voltage driving the inductive load. The DC blocking voltage (VR) of the free-wheeling diode can be found in the datasheet of a diode. The forward current should be equal or greater than the maximum current flowing through the load.

OFF

0 VDC

44 51 56 57 61 70 71 82 84 92 95 96 97 99 ST

338

+ _

Free-wheeling diode

Inductive load

Several hundred to several thousend volts

di __ e = L dt