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

Capacitive electrodes EL - Profibus PA 51
Diagnosis
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 con-
tact 4 and the vessel.
• Short-circuit (0 … 3 Ohm, optimum connection)
• Resistance > 3 Ohm
- corrosion on the mounting thread or flange
- possibly the mounting thread 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 Ohms 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 E030 Causes can be e.g. considerable changes of the DK value or
PA status 81, 82 incorrect settings.
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
- defective 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 correct power supply.
• If the error message does not extinguish, check the sensor for vis-
ible damage.
If you cannot find any faults, please call our service department.