20
7 Diagnostics and servicing
VEGATOR 121 •
57662-EN-210714
Cause
Rectification
Sensor not connected
correctly
•
In Ex systems, make sure that the Ex protection
is not influenced by the measuring instruments
used.
•
Measure the current and voltage on the connec-
tion cable to the sensor
•
Faults in the sensor causing a current change to
below 3.6 mA or over 21 mA lead to a fault signal
in the controllers.
•
The terminal voltage must be inside the specified
range. You can find this voltage range in the oper
-
ating instructions of the connected sensor.
Sensor delivers no (cor-
rect) switch-on pulse
•
Use sensor with switching-on pulse
•
Deactivate switch-on pulse monitoring
Sensor current < 3.6 mA
•
Check controller
•
Check the terminal voltage on the controller; if it
is < 17 V, the controller is defective -> exchange
controller or return it for repair
•
If the terminal voltage is > 17 V, disconnect the
sensor cable at the controller and replace it
with a 1 kΩ resistor. If the fault signal does not
disappear, the controller is defective -> exchange
controller or return it for repair
•
Check sensor or sensor cable
•
Reconnect the sensor cable to the controller,
disconnect the sensor and replace it with a 1 kΩ
resistor. If the fault signal does not disappear,
then the sensor cable is broken -> replace the
sensor cable
•
If there is no longer a fault signal on the line, the
sensor is defective -> exchange sensor or return
it for repair
Sensor current > 21 mA
•
Check controller
•
Disconnect sensor cable and replace it with a
1 kΩ resistor. If the fault signal does not disap
-
pear, the controller is defective -> exchange
controller or return it for repair
•
Check sensor or sensor cable
•
Reconnect the sensor cable to the controller,
disconnect the sensor and replace it with a 1 kΩ
resistor. If the fault signal does not disappear,
then the sensor cable is short-circuited -> elimi-
nate the short-circuit or replace the sensor cable
•
If there is no longer a fault signal on the line, the
sensor is defective -> exchange sensor or return
it for repair
7.4 How to proceed if a repair is necessary
You can find an instrument return form as well as detailed information
about the procedure in the download area of our homepage. By doing
this you help us carry out the repair quickly and without having to call
back for needed information.
In case of repair, proceed as follows:
Red fault LED lights up
