BBH SCU Series, Installation Manual

Page: 107 / 303

10
Safety-related characteristics
HB-37500-810-11-16F-EN SCU Installation Manual - Master and Slaves - SARC Page 107 of 303
Status: 09.06.2022
SAFETY NOTE • The fault can be optimized by choosing a suitable sensor resolution
for the corresponding application.
• For applications with limited resolution and/or time variance of the
sensing signal, the functional performance of the monitoring function
used can be improved by using an average filter. The average filter
"smoothes" digital spurious components of the sensors. However, this
is achieved at the cost of a longer response time of the overall
system.
• The filter time can be variably set between 0 and 64 in steps of 8. The
dimension is "msec". In order to determine the response time of the
overall system, the filter times must be added to the specified
response times of the SCU system (see chapter 9).
SAFETY NOTE • The manufacturer's data (MTTF
D
, FIT-numbers, etc.) must be used for
a safety related assessment of the partial system "Sensors".
• If the manufacturer demands specific diagnoses to be able to
guarantee the specified safety related characteristic values, these
must be checked with respect to the specific encoder as specified in
the table "Specific diagnostic measures for position and speed
sensors". If in doubt, the matter must be clarified by the
manufacturer.
• The DC-values listed in the table must be used conservatively and
compliance with
the boundary conditions (see table under „Remarks“)
must be ensured.
• In order to determine the DC-value for safety functions with standstill
monitoring a frequency assessment of the dynamic status may be
required. A DC of 90 % may here be used a s a guide value.
• According to the applicable standards, fault exclusions are permitted.
The boundary conditions mentioned in this context must permanently
be met.
• If several sensor systems are required for the correct function of a
single safety function, their partial values must be correctly merged
by following the chosen method. This applies also for a combination of
digital and analog sensors (e.g. safely reduced speed with open safety
door = door c encoder for speed detection)
• By choosing a suitable resolution of the sensor system a sufficiently
low tolerance with regard to the corresponding cut-off thresholds for
the individual safety functions must be ensured.
• When using the encoder input filter, one must consider the extension
of the response time when assessing the safety related function.