Encoder Mounting; Safety Assessment - Kübler Sendix SIL Serie Instrucciones De Uso

3.3.2 Safe absolute encoder function
In order to obtain safe information with the encoder regarding the absolute position, the controller
counts the incremental pulses (relative position) and compares the result with the absolute positions
also provided by the encoder. This allows detecting a deviation of both signals. The indicated position
is continuously verified by a comparison of the digital position data with the sine/cosine signals that are
also constantly being counted and compared by the controller.
3.3.3 Controller
The encoder is safe only when used in conjunction with a safe controller that can monitor the men-
tioned functions.
The encoder does not prevent the plant from switching on again after a malfunction; if this function is
necessary, it is to be ensured by the controller.
3.3.4 When switching the plant on and off
Prior to shutting down the plant, the controller must save the absolute position. When the plant is
switched back on, the controller compares the saved value with the new absolute value that has been
measured after power on.
If both values are identical, the position is still safe. If the position values are not identical, then the
position is not safe and it must be verified again.

3.4 Encoder mounting

The connection of the encoder and the driving unit must be safety-rated.
This concerns both the connection of the rotating element (shafts connection) and of the stationary
section (torque stop).
Kübler supplies the suitable mechanical interface for that purpose.
Shaft: Shaft with key/flat for formfit
Hollow shaft with safety-rated clamping ring.
Stator: The available tether arms, stator couplings and torque stops are safety-rated.
The risk of mechanical faults (as might occur, for example, if the rigid torque stop with torque pin was
to break or the encoder to fall off the motor shaft) is eliminated as a result of the mechanical over-di-
mensioning of the components of our Sendix® SIL encoders.
The mechanics and its connections can be considered as fault exclusions during safety assessment.
To achieve this fault exclusion, the mechanical limits of chapter "Technical data" and the correct
mounting of chapter "Mechanical installation" must be taken into consideration.

3.5 Safety assessment

To allow you defining the safety level of your machine, you will find the characteristic safety values in
chapter "Technical data".
You will also find the characteristic safety values of the Kübler products in the Internet, on the Kübler
website (www.kuebler.com) an in the Kübler library for the Sistema Software of the Institute for Occu-
pational Safety and Health of the German Social Accident Insurance (IFA).
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