46
9 Diagnostics and service
VEGABAR 81 • 4
… 20 mA
45025-EN-140228
9 Diagnostics and service
9.1 Maintenance
If the instrument is used properly, no special maintenance is required
in normal operation.
In some applications, product buildup on the diaphragm can influence
the measuring result. Depending on the sensor and application, take
precautions to ensure that heavy buildup, and especially a hardening
thereof, is avoided.
9.2 Rectify faults
The operator of the system is responsible for taking suitable meas
-
ures to rectify faults.
The first measures are:
•
Evaluation of fault messages, for example via the display and
adjustment module
•
Checking the output signal
•
Treatment of measurement errors
Further comprehensive diagnostics options are available with a PC
with PACTware and the suitable DTM. In many cases, the reasons can
be determined in this way and faults rectified.
Connect a multimeter in the suitable measuring range according to
the wiring plan. The following table describes possible errors in the
current signal and helps to remove them:
Error
Cause
Rectification
4
… 20 mA signal
not stable
– Fluctuations of
the measured
variable
– Set damping according to the
instrument via the display and
adjustment module or PACTware/
DTM
4
… 20 mA signal
missing
– Electrical con
-
nection faulty
– Check connection according to
chapter "
Connection steps
" and
if necessary, correct according to
chapter "
Wiring plan
"
– Voltage supply
missing
– Check cables for breaks; repair if
necessary
– Operating volt
-
age too low or
load resistance
too high
– Check, adapt if necessary
Current sig
-
nal greater than
22 mA or less
than 3.6 mA
– Electronics
module in the
sensor defec
-
tive
– Exchange the instrument or send it
in for repair
Depending on the reason for the fault and the measures taken, the
steps described in chapter "
Setup
" must be carried out again or must
be checked for plausibility and completeness.
Maintenance
Reaction when malfunc-
tions occur
Procedure for fault recti-
fication
Check the 4 … 20 mA
signal
Reaction after fault recti-
fication