Siemens SIPART Series - Settings; Safety characteristics

Functional safety
8.4 Settings
SIPART PS2 with and without HART
144 Operating Instructions, 10/2013, A5E00074631-11
8.4
Settings
No special parameter settings are required for the safety function.
Checking the safety function
Prerequisite for checking the safety function
● Positioner is in operation.
● The actuator belonging to the positioner is
not
in the safety position.
Procedure
● On the positioner, switch the signal source to 0 mA or the power supply source to 0 V.
● Always carry out the validation of the safety function with positioner and valve under
operating conditions.
Result
The actuator brings the valve to the specified safety position.
See also
Safety function (Page 141)
8.5
Safety characteristics
The safety characteristics necessary for use of the system are listed in the SIL declaration of
conformity. These values apply under the following conditions:
● The positioner is only used in applications with low demand rate for the "Low demand
mode".
● The positioner is blocked against unwanted and unauthorized changes/operation.
● The signal source with 0 mA or the power supply source with 0 V for the SIPART PS2
positioner is generated by a safe system that fulfills SIL 2 for single-channel operation.
● The connected single-acting type actuator returns the valve to the safe end position by
spring force in the following scenarios:
– At a chamber pressure (Y1 connection) up to a third of the maximum available intake
pressure (P
z
connection)
● The air outlet does not contain any additional cross-sectional contractions leading to an
increased dynamic pressure. In particular, a silencer is only allowed if icing or other
contamination is ruled out.
● The restrictor in the Y1 circuit may not be completely closed during operation.
● The auxiliary pneumatic power is free of oil, water and dirt in line with:
DIN/ISO 8573-1, maximum class 2