Stiction; Supply Air Too High - Siemens SIPART PS2 Service Manual

Troubleshooting Procedures

3.24 Stiction

If milliamp changes with input signal, check PS2 configuration.
● To restore all PS2 parameters to factory setting:
– From Auto/Manual mode, press and hold
– Press and release
– Press and hold
● Set configuration parameters as per application and re-initialize PS2, see Initialization
Procedure (Page 50)
3.24 Stiction
This term is used to identify the friction that exists in a valve assembly which prevents
smooth stem motion. An example is the initial friction that exists when pushing a heavy box
across the floor- first the pushing force must overcome the friction before the box will move.
If stiction is too great in a valve assembly, then the valve is unable to achieve small valve
movements, such as 0.1 %.
To identify this symptom:
● Put PS2 in Manual mode- from Auto press
● While using the
movements, for example 0.2 % movements.
● If the valve assembly cannot achieve these small movements manually, then there is too
much stiction.
● The way to quantify how much stiction exists is by how little the valve can move. For
example, if the smallest movement that can be achieved is 0.8 %, then this is the best the
valve assembly can move- in 0.8% increments. Therefore trying to achieve smaller
movements is impossible and will result in oscillations.
● Oscillations can be reduced by setting DeadBand value to "Auto".
3.25

Supply Air Too High

Maximum air pressure ratings are indicated on the actuator's name plate/stamp. Using too
much air pressure can inhibit performance and could damage actuator and/or positioner. The
PS2 positioner can handle up to 100 psi as long as the recommended actuator pressure is
not exceeded.
● Adjust supply pressure according to the application.
● If adjustments are made, run initialization process, see Initialization Procedure (Page 50).
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button and go to "PRST" parameter.
button until display shows: "OCAY"
and/or buttons try to move valve assembly in the smallest
button until display changes.
button once.
PS2 Troubleshooting Guide
Service Manual, 03/2017, A5E36661550-AA