VEGA Capacitive electrodes EK Profibus PA - Manual (Page 51)

Capacitive electrodes EK - Profibus PA 51
Diagnostics
Failure Measure, failure rectification
Contact 4 and vessel
The connection between contact 4 and the metal vessel (not instrument
hexagon or electrode flange) should be as good as possible. Measure
with an ohmmeter (range very low) the resistance value between
contact 4 and the vessel.
• Short circuit (0 … 3 Ohm, optimum connection)
• Resistance > 3 Ohm
- corrosion on the mounting thread or flange
- possibly the mounting boss was covered with Teflon tape or a
similar material
Check the connection to the vessel. If there is no connection, you can
connect a cable from the external grounding terminal to the vessel.
Make sure that coated flanges are always connected via the grounding
terminal to the vessel.
Contact 4 and 6
Values > 3 Ohm indicate a defect.
If you cannot find a failure in the sensor, then replace the oscillator with
a similar type (if available) or send the sensor for repair to VEGA.
After replacement of the electronics, a fresh adjustment must be carried
out (see "4 Setup").
Error message Invalid measured value
invalid measured The current measured value is outside the valid measuring range.
value Causes can be e.g. considerable changes of the DK value or incorrect
E030 settings.
PA status 81, 82 Change the current measuring conditions.
Error message Instrument error
Instrument error An error in the sensor was found.
E068
PA status 16, 68, 72
Possible causes are:
- supply voltage not within tolerance
- defect oscillator
- damage to the electrode or to the insulation
- electrode short-circuited against vessel wall
• Separate the sensor from power supply and then reconnect (cold
start).
• If the error message does not extinguish, check the sensor cable
and the power supply (correct voltage).
• If the error mesage does not extinguish, check the sensor for visible
damage.
If you cannot find any faults, please call our service department.