Siemens SIPART PS2 Service Manual page 65

SIPART PS2 Attributes
● Separate models for single and double-acting applications.
● Single-acting units vent output pressure upon loss of control signal and supply air.
● Double-acting units: Y1 goes to maximum pressure & Y2 vents upon loss of control
signal.
● Double-acting units block and trap output pressure in actuator upon loss of supply air.
● Double-acting units: If venting an output port upon loss of air is desired, we offer a venting
gauge block to exhaust output port Y2.
● Units with "F01" in the model code (Fail-in-Place) block and trap output pressure in
actuator upon loss of control signal. See Figure A-4 Reaction to failure of auxiliary power
with fail in place below.
Part Number
6DR4004-2RF
A6X30005128
Digital Communications
In addition to electric and pneumatic power, digital positioners require continuous digital
communication for proper operation. Both Foundation Fieldbus and Profibus power and
communicate with the PS2 using a single pair of wires. Therefore, it is possible to lose digital
communication and have device power.
The following Profibus and Foundation Fieldbus parameters will help you predict actuator
position upon loss of digital fieldbus communications only; for loss of electrical and
pneumatic power, see Figure A-3 Reaction to failure of auxiliary powers and Figure A-4
Reaction to failure of auxiliary power with fail in place below.
The following overview diagram shows the pneumatic connection variations for different
acutator types, regulating action and safety position after an auxiliary supply failure.
Before working on the control valve
Note that before working on the control valve, you must first move it to the safety position.
Make sure that the control valve has reached the safety position. If you only interrupt the
pneumatic auxiliary power supply to the positioner, the safety position may in some cases
only be attained after a certain delay period.
PS2 Troubleshooting Guide
Service Manual, 03/2017, A5E36661550-AA
CAUTION
A.4 SIPART PS2 Valve Positioner Fail-Safe Positions
Description
Venting gauge block, Aluminum
Venting gauge block, SST
Appendix A
63