VEGA Capacitive electrodes EL Profibus PA - Manual (Page 50)

50 Capacitive electrodes EL - Profibus PA
Diagnosis
5.4 Failure rectification
Failure Measure, failure rectification
Sensor defective, Test the internal connections:
measurement does • Loosen the 4 screws of the housing cover with a Phillips screwdriver
and remove the housing cover.
not react to level
changes
• Loosen the two small screws with a Phillips screwdriver and pull the
no display of oscillator out of the housing.
measured values
• Measure with an ohmmeter (range MOhm) the resistance values
between the following contacts:
C
M
- Capacitor
1 M
Ω
C
M
4
6 3
Screen
Contact 4 and middle pin (1)
The resistance must be 1 MOhm.
If the resistance is less, it indicates moisture in the housing or a defect
in the electrode insulation. A possible reason could be a non-insulated
electrode used in a conductive (moist) medium.
If the resistance is higher or if the connection is interrupted, the reason
is usually a bonding failure in the adapter plate or a resistor defective
due to strong electrostatic discharge.
In both cases, return the sensor to VEGA for repair.