Situations in which it is not possible to depressurize the actuator on demand or in the case of
a fault represent a dangerous failure.
WARNING
Disregarding conditions for fulfilling the safety function
Disregarding conditions can result in a malfunction of the process system or application, for
example, process pressure too high, maximum level exceeded.
The mandatory settings and conditions are listed in sections Settings (Page 238) and Safety
characteristics (Page 239).
● These conditions must be met in order to fulfill the safety function.
The pneumatic block of the positioner pressurizes and depressurizes the actuator. The
pneumatic block contains two pilot valves. The characteristic service life of the pneumatic block
depends on the load. On average it is approx. 200 million switching cycles for each of the two
pilot valves with symmetrical load. The number of control procedures for the switching cycles
is called in the local display or via the communication function. For more details, see Diagnostic
value '42.VENT1' / '43.VENT2' (Page 268).
NOTICE
Freezing of the exhaust air outlets
When devices of the type 6DR5..0/1/2/3 are used, the exhaust air outlets ② may freeze. The
function of the device is impaired.
● Do not install the positioner with the base plate ① pointing up.
① Base plate
② Exhaust air outlets
Figure 10-1 Exhaust air outlets, base plate
Functional safety
10.2 Safety function
SIPART PS2 with PROFIBUS PA
236 Operating Instructions, 05/2019, A5E00127926-AC
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