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GEL 2478 - Speed and Positioning Sensor

Target wheels and measuring rods can be
supplied separately.

Key features

  • Contactless measurement of linear or rotational movements
  • One or two channels
  • Magnetic measurement principle
  • Optionally available with:
    EC type-examination certificate
    BVS 07 ATEX E 030
    II 2 G Ex ib IIB T 4


  • Can be used under very harsh conditions
  • Registers speed between 0 Hz and a maximum of 25 kHz
  • Uses target wheels with modules1.0 to 3.5 (D.P.= 25.4 - 7.3) or measuring rods with 4.0 mm pitch
  • Large measuring distance (air gap) of up to 3 mm (depending on the gear module or the pitch of the target)
  • Very precise duty and phase shift of the output signals
  • Robust stainless steel housing
  • Very high protection class IP 68
  • Wide temperature -40°C to + 85°C (ATEX ) or -40°C...+120°C without ATEX certificate

Fields of application

  • Speed and position measurement in machines and motors
  • Position measurement on piston rods
  • Speed an position measurement in explosion-hazardous areas

Technical Data

Electrical Data
Supply voltage VS 10 ... 28 V DC (ATEX); VS = 10 ... 30 V DC without ATEX certificate, protected against polarity reversal
Safety-related parameters See section "Safety information"
Power consumption without load I B < 45 mA
Output signal Square-wave, short circuit-proof
Output voltage High = VS 1.8 V; Low = U < 0.5 V
Slew rate of output signal >10V/µs
Maximum output current per channel <10 mA
Frequency range 0 Hz... 25 KHz
Duty ratio of output signal 50 % ± 5%
Phase shift tracks 1 and 2 90° ± 20°
Electromagnetic compatibility rail vehicles: EN 50121-3-2 industry applications: EN 61000-6-1 to 4
Mechanical Data
Isolation strength (EN 60439-1) 500 V AC
Vibration protection (EN 61373 Kat.3) 200 m/s2
Shock protection (EN 61373 Kat.3) 2000 m/s2
Air gap See table "Air gap"
Module of target wheel / Pitch of measuring rod M = 1.0 ... 3.5 p = 4.0 mm
Operating and ambient temperature range -40°C ... + 85°C (ATEX) or -40°C ... +120°C without ATEX certification
Storage temperature range -40°C ... + 120°C
Screen connection Connected to sensor housing
Cable PUR or silicone depending on the version *)
Type of connection 6-core cable outlet (see cable assignment)
Cable cross-section 6 x 1.0 mm 2(PUR), 6 x 0.75 mm2 (silicone),
External diameter of cable da = 8.1 mm ± 0.2 mm (PUR) or da = 9.2 mm ± 0.4 mm (silicone)
Protection class IP 68
Housing Stainless steel; material 1.4305
Resistance of the measuring side <5 bar

Air gap depending on module or pitch

Measuring Scale Module/Pitch Air gap
Measuring target wheels M=1.0a=0.2 ... 1.4 mm
M=1.5a=0.2 ... 1.8 mm
M=2.0a=0.2 ... 2.2 mm
M=2.5a=0.2 ... 2.8 mm
M=3.5a=0.2 ... 3.0 mm
Measuring rods p=4.0mm a=0.2 ... 1.0 mm

*) Cable specification:
LK 1069 = PUR
LK 10581 = silicone on

Cable assignment,
Dimension drawing

Cable assignment

Signal pattern
(see type code)
Function PUR
LK 1069
LK 10581
E yellow 6
OV, GND blue 4
Vs*), GND red 1
F yellow 6
black 5
OV, GND blue 4
Vs*), GND red 1
V yellow 6
white 3
OV, GND blue 4
Vs*), GND red 1
X yellow 6
black 5
white 3
brown 2
OV, GND blue 4
Vs*), GND red 1

*) +V s=10 ... 28 V DC with ATEX certification
+V s=10 ... 28 V DC without ATEX certification

Dimension drawing

Assembly drawing for
scanning target wheels

Mounting postion 0° (A)
Mounting position 90° (B)

Assembly drawing for
scanning measuring rods

Mounting postion 0° (A)
Mounting position 90° (B)

Safety information

The following information must be observed when using sensors of type GEL 2478_Z with ATEX certificate in explosion-hazardous areas.

The maximum electrical and mechanical limiting values given in the technical data may not be exceeded. The following safety parameters apply to the GEL 2478 sensor:

Ignition protection type: IIG Ex ib IIB T4
Ui ≤ 28 V DC
Ii ≤ 250 mA
Pi ≤ 1000 mW
Li = 0 mH
Ci = 480 nF
Cable characteristics:
Lc = 0,018 mH / 100 m
Cc = 18 nF / 100 m

The sensor may be operated only within the specified operational temperature range, namely -40°C.. .+ 85°C. The cables between the power inlet and the GEL 2478 sensor and between the sensor and the external evaluation unit may not exceed the specified maximum length. Connection and installation of the safety barriers may be carried out only by certificated personnel; installation of modules relevant to explosion hazards may be carried out only by authorised expert technicians. The cables and housing of the GEL 2478 sensor must be undamaged: in the event that these elements are damaged then the unit may not be installed.

EC type-examination certificate BVS 07 ATEX E 030 for sensor type GEL 2478_Z dated 09.03.2007.
The certificate is available on request.

Description of a protective circuit as shown in the example (see next page).

The power supply is connected to the 9002/13-280-110-001 safety barrier. This safety barrier limits the current flowing in the EEX circuit to at most 119 mA and the voltage to at most 28 V. The output signals from the GEL 2478 sensor are connected to the 9002/11-120-024-001 safety barrier. In the event of a malfunction, this barrier limits the current to at most 12 mA and the voltage to at most 12 V. The 9002/11-120-024-001 safety barrier routes each of the output signals to a DEK 0E 5DC/ 24CD/1 00 kHz optocoupler. These optocouplers serve to convert the output signals back to a range that can be evaluated by the SPS.

Summary of the resource parameters

Nr.: Corresponding resource Manufacturer U0
Designation Type
1 Safety barrier 9002/13-280-110-001 Stahl 28 110 770 9 635 IIB
2 Safety barrier 9002/11-120-024-001 Stahl 12 24 70 230 7100 IIB


DEK 0E 5DC/24DC/100 kHz; article no.: 29 64 27 0
Supplier: Phoenix Contact GmbH & Co.KG; Blomberg

Example of protective circuitry

The following diagram shows one possible protective circuit for the GEL 2478 sensor using safety barriers. The safety barriers and optocouplers are not supplied with the GEL 2478 sensor.

Type code