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Series 6A Installation, Operation & Maintenance – Troubleshooting
6A O & M : 28
Fault profile (symptoms) Possible cause(s) Remedial measures
In stationary automatic mode
(constant setpoint) and in man-
ual mode, both piezo valves
continually switch alternately,
and the actuator oscillates
around a mean value.
Sticking friction of the packing gland from the
control valve or actuator too large
Reduce friction or increase dead zone of positioner
(parameter ”dEbA”) 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 seating of lever on
positioner shaft
Correct any other play between the actuator and the
control valve
Actuator is too fast
Positioner doesn’t move con-
trol valve to the stop (at 20
mA)
Supply pressure too low. Load on the feeding
controller or system output is too low
Increase supply pressure, insert ballast converter
Select 3/4-wire mode
Remedial Measures Table 4
Remedial Measures Table 5
Fault profile (symptoms) Possible cause(s) Remedial measures
Zero point displaces sporad-
ically (> 3%).
Impact or shock loads result in accel-
erations so high that the friction clutch
moves, e.g. due to ”vapor shocks” in
vapor lines
Rectify the causes for shock loads
Re-initialize the positioner
The device function has
completely failed: no view
even on the digital display.
Electrical auxiliary power supply is not
adequate
Check the electrical auxiliary power supply
In case of very high continuous loads due
to vibrations (oscillations):
Screws of the electrical connecting termi-
nals may be loose
Electrical connecting terminals and/or
electronic components may be knocked
out
Tighten the screws firmly x
Repair
1)
For prevention: install the positioner on the damping pads
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