Safety Loop; Safety Values - ABB AC500-S Safety User Manual

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2.3 Safety loop

The safety loop, to which the AC500-S safety PLC belongs, consists of the following three parts:

sensors, safety PLC and actuators.

Fig. 2: Typical safety loop with AC500-S safety PLC

For the calculation of the PFH/PFD values of an exemplary safety system, a maximum of 15 %

is assumed for the safety PLC.

Table 1: The following safety values shall be used for AC500-S safety modules:

SM560-S(-XC) /

SM560-S-FD-1(-

XC) / SM560- S-

AI581-S(-XC)

DI581-S(-XC)

DX581-S(-XC)

DX581-S(-XC)

with parameter

DX581-S(-XC)

with parameter

Detection = "Off"

~35 % of safety loop PFH

3ADR025091M0208, 12, en_US

Safety Input

~1 5 % of safety loop PFH

Overview of AC500-S safety PLC

Safety Output

~50 % of safety loop PFH

Safety values