bürkert 8718 Bedienungsanleitung Seite 44

Problem
Error LED flashes
No flow-rate available
Actual value fluctuates
Set-point value = 0 %,
flow-rate still available
Set-point value = 0 %,
valve is closed,
no flow-rate available;
however, actual value
output indicates a low
flow-rate
Set-point value is not
reached
Table 10: Malfunctions
44
Possible cause
The residual ripple of the power supply
voltage is too high.
A serious fault has occurred, e.g.
broken sensor or fault in the internal
power supply.
The sensor was operated above
the permitted maximum operating
pressure.
The set-point value is below the limit
for the zero point shut-off.
The device is in an operating state
other than standard controlled
operation.
The pipelines have been sized too large
or may not yet have been completely
deaerated.
FE connection not correct.
The controller is continuously cor-
recting malfunctions in an unstable
pressure supply, e.g. by pumping.
The residual ripple of the power supply
voltage is too high.
The operating pressure is above the
maximum operating pressure of the
valve.
The mounting position of the device is
incorrect.
A fluid is used other than that desig-
nated by the calibration.
The filter is blocked.
The primary pressure is too low.
The back pressure is too high.
english
Type 8718, 8719 / 8708, 8709
Maintenance, Troubleshooting
Remedial action
Use a power supply with a smooth
output voltage at the required power.
Return device to the manufacturer to
have the fault repaired.
Reduce operating pressure.
Return device to the manufacturer to
have the fault repaired.
Increase set-point value to > 10 % of
the nominal flow-rate.
Check operating state, see also
chapter 8.3. Functions of the LFC /
LFM.
Deaerate lines.
Change pipe size.
Connect FE to the earthing point
(as short as possible, wire at least
2.5 mm²).
Connect suitable pressure controller
upstream.
Install buffer tank to absorb pressure
fluctuations.
Use power supply with a smooth
output voltage at the required power.
Reduce the operating pressure.
Return device to the manufacturer to
have the fault repaired.
Install LFC in the calibrated mounting
position and run an Autotune function
to adjust to the operating conditions.
Return device to the manufacturer for
recalibration for the operating fluid.
Clean or replace filter.
Increase primary pressure to calibration
pressure.
Check system components for soiling
on output side and if required clean.