Functional Safety; Relevant Standards; Safety Functions; Safety Concept - Kübler Sendix SIL Instrucciones De Uso

3. Functional safety

The safety-rated Sendix
regarding rotational speed, direction of rotation and position. This requires a higher-level safe encoder
controller, since the encoder cannot trigger on its own initiative actions such as initiating a safe condi-
tion using its encoder-internal diagnostics.
Increased requirements apply to the electrical and mechanical coupling of the encoder.

3.1 Relevant standards

The safety assessment of the encoder is performed on the basis of the following standards and safety
classes:
Sendix SIL
®
Safety classes/Relevant standards

3.2 Safety Functions

According to EN 61800-5-2, the following safety functions can be achieved with the encoder:
SS1: Safe Stop 1
SS2: Safe Stop 2
SOS: Safe Operating Stop
SLS: Safely-Limited Speed
SSM: Safe Speed Monitor
SSR: Safe Speed Range
SDI: Safe Direction
SLA: Safely-Limited Acceleration
SAR: Safe Acceleration Range
SLI: Safely-Limited Increment
SLP: Safely-Limited Position
SCA: Safe Cam

3.3 Safety Concept

3.3.1 Safe incremental encoder function

In order to achieve safe incremental information with the encoder, the controller must monitor the
validity of the analogue signals. To that purpose, the error presumptions of standard 61800-5-2 Table
D16 must be controlled, e. g. with the help of the function sin² (x) + cos² (x) = 1.
The recommended tolerance range for the encoder lies between 0.5 and 1.5. However this value
must be verified with the desired safety function. Factors that must also be considered here include
the scanning frequency, the input circuitry and the calculated evaluation of the SinCos signals in the
controller. For this reason the manufacturer of the controller must once again verify the tolerance limits
of the sin²(x) +cos²(x) function. The validity of the safety function can be analysed at any time. This
means that for a resolution of 2048 sine/cosine periods, the validity can be checked by the controller
2048 times per revolution. With a tolerance of the sin²(x) + cos²(x) function of +/-0.5, the max. possible
error path is 10% of one signal period (36° el.).
SIL encoders are designed for the implementation of safety-related functions
®
• Safety Integrity Level (SIL)
in compliance with EN 61800-5-2
• Performance Level (PL)
in compliance with EN ISO 13849-1
ENG - 9
(R 6070 9.0009)