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
1. In order to test the safety shutdown, apply a LOW level, i.e. a voltage of maximum 4.5 V, to
the input for the safety shutdown.
2. Verify that the valve returns to the safety position.
3. In order to test the response of the actuator, apply a HIGH level, i.e. a voltage >13 V, to the
input for the safety shutdown.
4. Set the setpoint to 50% using a local operation (manual operation) or bus communication.
5. Reduce the inlet pressure (PZ) to a third of the maximum supply pressure.
6. Verify that the valve returns to the safety position.
7. Check the filters in the pneumatic connections for contamination and clean them if
necessary.
See also
Overview of device components (Page 28)
Safety function (Page 235)
10.5 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".
● "Jumper" on the basic electronic system was plugged into the left position facing the
terminals at position "Shut Down enabled" or removed completely.
● The positioner is blocked against unwanted and unauthorized changes/operation.
● The shut-off signal for the positioner is generated at the input for the safety shutdown
(terminals 81 and 82) by a safe system which meets at least SIL 2. The LOW level has a
maximum of 4.5 V at the input terminals.
● The connected actuator must be singe-acting and return the valve to the safe end position
by spring force in the following scenario:
– 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.
Functional safety
10.5 Safety characteristics
SIPART PS2 with PROFIBUS PA
Operating Instructions, 05/2019, A5E00127926-AC 239
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