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Fault description (symp-
toms)
The two piezo valve
•
constantly switch
alternately in stationary
automatic mode
automatic mode
(constant setpoint),
actuator oscillates
around a middle point
Table 6
Fault description (symp-
toms)
Zero point shifts spo-
•
radically (> 3 %)
Device function breaks •
Device function breaks
•
down totally: no dis-
play
Table 7
SIPART PS2 PA Manual
A5E00127926--05
Possible cause(s)
Static friction on the packing
•
glands of the fittings or actuator
too high
Play in the positioner, actuator,
•
fittings system
Actuator too fast
•
Possible cause(s)
Such high accelerations have
•
occurred through impact or
shock that the friction clutch has
shifted (e.g. through steam jets
in the steam pipelines)
Insufficient electrical supply
With very high continuous stresses
by vibrations, the following can
occur:
Screws of the electrical termi-
•
nals can loosen
The electrical terminals and/or
•
electronic modules can be
shaken loose
Corrective actions
Reduce static friction or increase
•
dead zone of positioner (parameter
dEbA) until the oscillating
movements stop.
Linear actuator:
•
Check seating of the stub screw of
the coupling wheel
part--turn actuator:
•
Check seating of the lever on the
positioner shaft
Correct any other play between the
•
actuator and fittings
Increase positioning times by
•
means of restrictor screws
If fast positioning times are
•
required, increase dead zone
(parameter dEbA) until the
oscillating movements stop.
Corrective actions
Shut off the cause of the shocks
•
Reinitialize the positioner
•
Upgrade see page 160 mount
•
reinforced friction clutch (order
number C73451--A430--D14)
Check electrical supply
•
Tighten screws and secure with
•
sealing varnish
Repair see page 160
•
Prevention: Mount the positioner
•
on rubber metal
Operation
129
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