KROHNE SU 501 EX EN - Manual (Page 21)

+
-
V mA
12... 20V 4... 20mA
1
2
1 2 3 4
Fig. 8: Connection of a multimeter
1 SU 501 Ex signal conditioning instrument
2 Sensor
l Sensor not connected correctly
à
Measure the voltage on the connection cable
In Ex systems, make sure that the Ex protection is not
influenced by the measuring instruments used.
à
The terminal voltage of the sensor is at least 12 V in
normal condition
?
The red failure LED of the signal conditioning instrument
lights
l Current value <2 mA
à
Measure the current value on the signal cable to the
sensor
1 Check all connections and connection cables to the sensor
The voltage should be approx. 17 … 20 V
If the value is below 17 V, probably the signal conditioning
instrument is defective.
Exchange signal conditioning instrument or return it for
repair
2 If the red failure lamp continues to light, separate the
sensor from the connection cable and connect a resistor of
1 kOhm instead on the signal conditioning instrument
The signal conditioning instrument is defective if the failure
lamp continues to light
SU 501 Ex - Signal conditioning instrument 21
Maintenance and fault rectification
27953
-EN
-050616