VEGA VEGADIF 34 … 51 - Manual (Page 57)

VEGADIF 34 … 51 57
20094-EN-030731
Diagnostics
6 Diagnostics
Maintenance
VEGADIF 34 … 51 differential pressure trans-
mitters are maintenance-free. Only the wetted
parts are subject to a certain amount of wear.
Therefore check regularly the condition of
these parts, particularly the diaphragms and
process seals. Note the service instructions
VEGADIF 34 … 51 differential pressure trans-
mitter.
Repair
If the measures for failure rectification are not
successful, return the affected instrument for
repair to VEGA. Please note the following:
• Attach information: application, medium,
failure description.
• Remove buildup, especially it is composed
of substances hazardous to health.
Fault rectification
Through self-monitoring, VEGADIF differential
pressure transmitters offer a high degree of
reliability. Within the framework of self-monitor-
ing, the signal circuit 4 … 20 mA is additionally
used for transmission of failure information. If a
failure is detected, the output current takes on
a value of 21.5 mA. Before removing VEGADIF
to look for faults, the following should be
checked:
- atmospheric pressure compensation (for
level measurements on open vessels)
- electrical components and connections
Checking the electrical components
1
+
2
-
3
4 ... 20 mA
+
-
~
+
–
V mA
VEGADIF
terminals
Voltage Current
External
energy source
Instructions for Ex applications
Deviating from the above arrangement, termi-
nal 1 and tag 1 are used only for short-term
connection to a certified, active floating (max.
value: 470 mW) or to any passive floating
measuring instrument. When connecting, the
regulations for wiring intrinsically safe circuits
(measuring instrument, supply and signal
circuit) must be noted.
External overvoltage arresters
(if present)
- check on interruption and short-circuit.
Voltage
- the terminal voltage on the differential pres-
sure transmitter must be at least
11.5 V DC.
- the supply voltage for the differential pres-
sure transmitter, provided by e.g. a
VEGAMET signal conditioning instrument,
must be approx. 25 V DC.
Current
Current value Condition
3.8 … 20.6 mA standard range of the output
current
21.5 mA fault signal
0 mA signal cable interrupted
< 3.6 mA electronics or pressure sensor
element defective
> 21.6 mA short-circuit in the signal cable,
electronics or pressure sensor
element defective