Fault profile (symptoms) Possible cause(s) Remedy
The pneumatic block does not switch. A
gentle click sound is also not audible
when the or buttons are pressed
in manual mode.
● The screw between the cover and
the pneumatic block has not been
tightened firmly or the cover is jam‐
med.
● Tighten the screw firmly; if required,
rectify the deadlock.
● Dirt (swarf, particles) in the pneumat‐
ic block
● Repair or a new device; built-in fine
screen, can also be replaced and
cleaned.
● Deposits on the contacts between
the electronic printed circuit board
and the pneumatic block can devel‐
op due to abrasion owing to continu‐
ous loads resulting from strong vi‐
brations.
● Clean all contact surfaces with spirit;
bend the pneumatic block contact
springs slightly if required.
Actuator does not move.
● Compressed air < 1.4 bar ● Set supply pressure PZ to > 1.4 bar.
Pneumatic block does not switch (how‐
ever, a gentle clicking sound can be
heard when the or button is press‐
ed in "Manual" mode.)
● Restrictor valve turned off (screw at
the right endstop)
● Open the restrictor screw by turning
it to the left.
● Dirt in the pneumatic block ● Repair or a new device; built-in fine
screen, can also be replaced and
cleaned.
A pneumatic block continually switches
in stationary automatic mode (constant
setpoint) and in "Manual" mode.
● Pneumatic leakage in the positioner
- actuator system; start the leakage
test in "RUN 3" (initialization).
● Rectify leakage in the actuator
and/or feed line.
● In case of an intact actuator and tight
feed line: Repair or new device
● Dirt in the pneumatic block ● Repair or a new device; built-in fine
screen, can also be replaced and
cleaned.
In stationary automatic mode (constant
setpoint) and in "Manual" mode, the
pneumatic block continually switches
and the actuator oscillates around a
mean value.
● Stiction of the packing gland from
the control valve or actuator too large
● Reduce stiction or increase dead‐
band of positioner (parameter "dE‐
bA") until the oscillation stops.
● Looseness (play) in the positioner/
actuator/control valve system
● Part-turn actuator: Check for firm
seating of set screw on coupling
wheel.
● Linear actuator: Check for firm seat‐
ing of lever on positioner shaft.
● Correct any other play between the
actuator and the control valve.
● Actuator too fast ● Increase travel times using restrictor
screws.
● If a quick travel time is needed, in‐
crease the deadband (parameter
"dEbA") until the oscillation stops.
Positioner does not move control valve
to the endstop (at 20 mA).
● Supply pressure too low. Load on
the feeding controller or system out‐
put is too low.
● Increase supply pressure, insert bal‐
last converter
● Select 3/4-wire mode.
Diagnostics and troubleshooting
11.4 Fault and remedy
SIPART PS2 with 4 to 20 mA/HART
236 Operating Instructions, 11/2019, A5E00074631-AE
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