Possible Architectures, Achievable Safety Levels And Prerequisites; Application Examples - ABB PLUTO Safety-PLC Operating Instructions Manual

4.4.7 Possible architectures, achievable safety levels and prerequisites

This table is an overview of safety levels for different applications.
The achievable Cat / SIL / PL depends on the sensor which is used in the application and the
detection capability of faults listed in IEC 61800-5-2, table D.16.
Structure
1 sensor/encoder
2 sensors/encoders
homogeneous
redundant
2 sensors/encoders
diverse redundant

4.4.7.1 Application examples

Example with two incremental encoders.
Usage Achievable
Cat/ PL/ SIL
Overspeed Cat 2 / PL c
SIL 1
Stand still Cat 2 / PL c
monitoring SIL 1
Overspeed Cat 3 / PL d
SIL 3
Stand still Cat 3 / PL d
monitoring SIL 2
Overspeed Cat 4 / PL e
SIL 3
Stand still Cat 3 / PL d
monitoring SIL 2
Prerequisites, necessary diagnostic to be
realized in the application program
Monitoring of dynamic behavior.
(E.g. Stand still is off at expected movement)
Monitoring of dynamic behavior. Stand still
should not last in more than approx. 1 hour
Monitoring of dynamic behavior.
(E.g. Stand still is off at expected movement)
Monitoring of dynamic behavior. Stand still
should not last in more than approx. 1 hour
Monitoring of dynamic behavior.
(E.g. Stand still is off at expected movement)
Monitoring of dynamic behavior. Stand still
should not last in more than approx. 1 hour
Example of two channel solution with one
encoder and a second channel from a
frequency converter. (Cat 3/PL d/SIL 2)
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