Free Sensor Sample Order Now

Tandem encoder GEL 290


The tandem encoder GEL 290 was specially developed for applications with high requirements on redundancy.
Several independently operating encoders are mounted on the drive shaft as one unit. The length of the encoder system is reduced to a minimum by design measures.
The tandem encoder is made up for each specific application.
The measuring scale on the rotary encoder used is of robust design so that it can even withstand extreme impacts and vibration. The magnetic sensors are resistant to harsh environmental conditions such as dirt, oil, humidity or condensation due to temperature differences. The rotary encoder contains bearings that ensure maintenance-free, durable operation in the harshest operating conditions.

  • Modular design
  • Max. 3 systems
  • Combination of incremental rotary encoder and absoluterotary encoder
  • Resolution
    - Incremental rotary encoder 266240 increments per turn
    - Absolute rotary encoder 65536 steps per turn
  • Protection class (overall system) IP66
  • Solution individually tailored to the specific application
  • Various signals redundant due to flexible design
  • Maintenance-free, durable operation in harshest ambient conditions due to selected bearing and measuring systems
Field of application
  • General mechanical engineering
  • Process automation
  • Wind power / regenerative energies



The concept of the tandem encoder foresees the mounting of several independently operating encoders on one shaft. For this purpose, the encoders have been equipped with a continuous shaft or hollow shaft. In this way the requirements from process automation and process data acquisition for checking and safeguarding processes at the same time can be realised. The length of the encoder system has been kept as short as possible to permit trouble-free usage in practice.

Modular design

The tandem solution allows assembly of different encoders in a relatively short set.
A central element of the tandem encoder is the incremental rotary encoder GEL 292, this device must be included at least once in each tandem system. The incremental rotary encoders are equipped with a flexibly mounted hollow shaft into which coupling elements with an accurate fit are inserted; in this way space is saved on fitting together the encoders.
The terminating element on a tandem encoder can be an incremental encoder with hollow shaft GEL 293 or an absolute rotary encoder with synchro-flange GEL 235. The absolute rotary encoder GEL 235 is available with various interfaces and bus covers (see Absolute rotary encoder GEL 235 – interfaces).
The incremental rotary encoders GEL 292 and GEL 293 are technically identical and vary only in the housing design.


Sectional view of a tandem encoder with basic module GEL 292 and incremental rotary encoder GEL 293

Technical data - incremental rotary encoder GEL 292 / 293
Measuring range 40 ... 266240 steps
Accuracy 0.005°
Electrical data
Supply voltage VS 5 V DC ± 5% 10 to 30 V DC
Power consumption ≤ 1.3 W, without load
Logik level TTL HTL
Mechanical data
Moment of inertia of rotor 8 . 10-5 kgm2
Max. operating speed (r.p.m.) 8,000 min-1
Weight 0.7 kg per system
Admissible coupling offset

±1 mm
±0.5 mm
Bearing life cycle at axial load > 15.000 . 106 revolutions
Housing stainless steel, X12CrMoS17-1,4104
Ambient data
Working temperature range -40 °C to +85 °C
Operating temperature range -40 °C to +85 °C
Storage temperature range -40 °C to +105 °C
Degree of Protection (EN 60529) IP 66
Vibration protection (DIN EN 60068-2-6) 100 m/s2, 10 to 2000 Hz
Shock protection (DIN EN 60068-2-27) 1000 m/s2, 11 ms
EMC EN 61000-6-1 to 4
Insulation strength (DIN EN 60439-1) Ri > 1 MΩ at 500 V AC

Technical data - absolute rotary encoder GEL 235

Incremental deviation < 0.01°
Accurary ± 0.08°
Electrical data
Operating voltage 10 to 30 V DC with reverse voltage protection (option: 5 V - 5%, +25%)
Power consumption < 1.6 W, without load
Resolution Singleturn (ST) 8, 9, 10 to 16 Bit (measuring steps over 360°)
Resolution Multiturn (MT) 4, 8, 12 Bit (revolution, mechanical gear)
Interface SSI, PROFIBUS Encoder Profile V 1.1, EtherCAT (CoE), CANopen Encoder Profile DS406, analogue 4 to 20 mA
Analogue output signal Sin/Cos difference signal 1 VPP, 64 periods per resolution
Mechanical data
Moment of inertia of rotor 611.8.10-6 kgm2
Material anodised aluminium
Weight Singleturn 300 g
Weight Multiturn 310 g
Operating speed (limit value) Singleturn 12,000 min-1
Operating speed (limit value) Multiturn 10,000 min-1, 12,000 min-1(short-term)
Operating torque < 3 Ncm
Bearing life cycle > 105 at 1000 min-1
Shaft sealing ring Material: Viton, protection class: IP 67, reduced operating speed: max. 6,000 min-1
Ambient data
Working temperature range -40 °C to +85 °C
Operating temperature range -40 °C to +105 °C
Storage temperature range -40 °C to +85 °C
Degree of Protection (acc. to DIN 60529) IP 67
Vibration protection (DIN EN 60068-2-6) 200 m/s2, 10 to 2,000 Hz
Shock protection (DIN EN 60068-2-27) 2000 m/s2, 11 ms
EMC EN 61000-6-1 to -4
Insulation strength Ri > 1 MΩ at 500 V AC
Relative humidity of air max. 99 %
Condensation permissible
Synchro flange
Shaft load (radial/axial) at 1,000 min-1 = 70 N / 50 N,
at 6,000 min-1 = 50 N / 40 N