ABB BT50 Manuale - Pagina 12

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ABB BT50 Manuale
9

System Structure

Assumptions

The following assumptions have been made during the FMEDA analysis:
·
The device shall claim less than 35% of the total failure budget for a SIL3 safety loop.
·
Failure rate based on the Siemens SN29500 standard. 2004-01
·
Failure rates are constant, wear out mechanisms are not included.
·
External power supply failure rates are not included.
·
The safety-related device is considered to be of type A components with a Hardware Fault Tolerance of 1.
·
It is assumed that the device will be used under average industrial ambient conditions according to the
technical data.

Safety Function and Safe State

Safety Function
When the input of the BT50 is de-energized, the output is de-energized. When the input of the BT50T is de-
energized, the output is de-energized according to the time settings.
Safe state
The safe state is when all three NO safety outputs are de-energized.
Switching Frequency
The maximum switching frequency in the safety relevant input is 0,3 Hz.
2TLC172316M0201, rev E
2015-09-30
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