General information

Encoder technology

The task of an encoder is to detect the angular position of the motor shaft or the change of the angular position, and to pass on this information to a unit that evaluates this data, such as a PLC or frequency inverter.

This information is used to determine the rotational speed and angular acceleration. The evaluating unit (inverter, encoder card) can then monitor or control the speed and position the drive system accordingly.

Encoder in closed loop system

Encoders are connected to the inverter and allow for further improved motor control.

  • The motor can be operated in positioning control or for a simple positioning task.
  • The quality of torque control can be improved significantly.
  • The quality of speed control can be improved significantly.
Encoder design

Encoders are available in various designs:

  • Incremental encoders, single-turn absolute encoders, multi-turn absolute encoders
  • Built-in encoders integrated in the motor and add-on encoders mounted to the motor
  • Different mechanical connections of the motor shaft with the encoder.
  • Different electrical connection options, such as terminal strip or plug connector.
  • Different output signals: sin/cos, HTL, TTL, SSI, RS485 + sin/cos, HIPERFACE®, MOVILINK® DDI, resolvers
  • With or without electronic nameplate for startup on SEW‑EURODRIVE inverters.
  • Different resolutions and number of counted revolutions.
  • Available for order ex works or mechanically prepared through mounting adapters for retrofitting
  • Various mechanical preparations for mounting encoders subsequently
  • Design as a safety encoder for implementing safety functions.
  • Design as an encoder for use in potentially explosive areas according to ATEX/IECEx and HazLoc-NA®

SEW‑EURODRIVE offers a wide range of encoders for different applications and different inverters. Before selecting the encoder, check the application environment as well as the encoder interface of the inverter.

Electronic nameplate

With EI8Z, E.8S, EK8W, EK8Z, EK9Z, AK8H, A.8W, and AK8Z encoders, important startup data are stored in an electronic nameplate. This facilitates starting up the drive and ensures that motor parameters are set correctly in the inverter.

During startup, the engineering software checks whether an electronic nameplate is present in the encoder and gives a suggestion to the user about how to use this data.

Advantages of auto identification of the drive:

  • Complete and correct identification of encoder, motor, and gear unit
  • No manual entry of data is necessary, which saves time during startup.
  • Easy startup of drives that are installed in locations that are difficult to access.
Modular encoder system

The modular encoder concept is standardized and improved. The encoders of the spread shaft (.S7.), plug-in shaft (.G7.), and hollow shaft (.H7.) variants have been converted into encoder variants with a cone shaft (.K8./.K9.). You will find significant advantages of the improved encoders in the following chapters.

Built-in encoders (EI..)
  • EI7. and EI8. built-in encoders.
    • This encoder is integrated in the motor in a particular compact manner without adding extra length to the motor.
    • Brake wear can be measured without removing the encoder.
    • The encoder can be retrofitted.
    • The encoder does not have its own bearing. This is why the encoder is wear-free during operation and is suited for rough operating conditions, also with frequent working brake operations.

The EI7. encoder family is currently built in its second generation by SEW-EURODRIVE. The version ID EI7. B and EI7C FS is not listed in the type designation, however, and is therefore not listed in this document.

The add-on encoder is mounted to the motor on the B-side of the motor by means of various tool flanges. The standard for this is a conical shaft connection.

Cone shaft
  • Encoders with cone shaft .K8./.K9.
    • The encoder type is available for sizes 63 to 355.
    • The encoders are available as safety encoders for implementing safety functions.
    • The encoders are suited for use in explosion-protected motors.
    • It is possible to measure the brake wear without removing the encoder.
    • The cone shaft connection is particularly robust and accurate.

Further product information and installation instructions for cone shaft encoders from SEW-EURODRIVE can be found via the following links:

DE: https://youtu.be/0vamJrbOUAk

EN: https://youtu.be/8-D5meLW7cg

Spread shaft (.S7.), plug-in shaft (.G7.), hollow shaft (.H7.)

The encoders with spread, plug-in, and hollow shafts are replaced by encoders with a cone shaft (.K8./.K9.) and by built-in encoders (EI..). We recommend switching to the new encoder types in order to take advantage of the numerous advantages mentioned above. You can find more information on our website:

https://www.sew-eurodrive.de/products/motors/ac_motors/accessories_and_options/encoders/encoders.html

Additional information