Siemens SIPART PS2 Service Manual page 42

Troubleshooting Procedures
3.29 Valve Block Failure
If PS2 can output full supply pressure and fully exhaust, then something else is preventing
actuator from fully closing or opening. Check valve assembly for mechanical blockage and
air leaks. Also verify supply is at required pressure for application.
● If possible, drive actuator/valve to a mid-travel position (50 %). Does air pressure hold
when the buttons are released?
– If yes, the valve block/PS2 is working correctly.
– If not, check for leaks and perform the Pipe Plug Test at the end of this section.
● Does the unit exhaust?
– For double-acting, the unit should always exhaust during movement. For single-acting,
– If one of the output ports does not exhaust, check exhaust port for blockage.
– If unit always exhausts, verify parameter "PNEUM" is set correctly.
Pipe Plug Test
● Turn off supply air to PS2.
● Slowly remove pneumatic connections from output port(s) on the positioner.
40
the unit will only exhaust in one direction.
○ If exhaust port is free from blockage, go to Pipe Plug Test at the end of this section.
○ "Std" = Standard Valve Block or "FIP" = Fail in Place Valve Block ("F01" at end of
the model code indicates FIP option).
○ If this is set correctly, go to the Pipe Plug Test.
WARNING
High Pressure
High pressure output port(s) may still contain air pressure and can cause injury. Use
caution when removing pneumatic connections.
PS2 Troubleshooting Guide
Service Manual, 03/2017, A5E36661550-AA