KROHNE SU 501 EX EN - Manual (Page 20)

7 Maintenance and fault rectification
7.1 Maintenance
When used as directed in normal operation, SU 501 Ex is
completely maintenance-free.
7.2 Fault rectification
SU 501 Ex offers maximum reliability. Nevertheless faults can
occur during operation. These may be caused by the following,
e.g.:
l
Measured value of the sensor not correct
l
Power supply
l
Interference on the cables
The first measures are checking the input and output signal.
The procedure is described as follows. In many cases the
causes can be determined and faults can be rectified.
?
The red failure LED of the signal conditioning instrument
lights
l Sensor not connected correctly
à
Measure the current value on the signal cable to the
sensor
In Ex systems, make sure that the Ex protection is not
influenced by the measuring instruments used.
à
Faults on the sensor causing a current change below
2 mA or above 23 mA, cause a fault signal on
measuring instruments.
Causes of malfunction
Fault rectification
Failure
20 SU 501 Ex - Signal conditioning instrument
Maintenance and fault rectification
27953
-EN
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