Endress+Hauser Prosonic S FMU90 - Page 25

Wiring
25
4.3.2 Connection hints
"
Caution!
In order to avoid interference signals, the sensor cables should not be laid parallel to high voltage
electric power lines. The cables may not be laid in the proximity to frequency converters.
"
Caution!
The cable screen serves as a return cable and must be connected to the transmitter without any
electrical break. With the pre-assembled cables, the screen ends in a black strand (BK). With the
extension cable, the screen must be twisted together and connected to the "BK" terminal.
#
Warning!
The sensors FDU83, FDU84, FDU85 and FDU86 with an ATEX, FM or CSA certificate are not
certified for connection to the FMU90 transmitter.
#
Warning!
for the sensors FDU91F/93/95/96 and FDU83/84/85/86:
The ground lead (GNYE) must be connected to the local potential equalization after a maximum
distance of 30 m. This can be done
• either at the terminal box
• or at the transmitter FMU90 or in the cabinet (if the distance to the sensor does not exceed 30 m).
!
Note!
For easier mounting it is advisable to use the sensors FDU91/92 and FDU80/80F/81/81F/82 with
a maximum cable length of 30 m as well. For longer distances an extension cable with a terminal
box should be used.
4.3.3 Extenxion cables for the sensors
For distances up to 30 m the sensor can be directly connected by the sensor cable. For longer
distances, it is recommended to use an extension cable. The extension cable is connected via a
terminal box. The total length (sensor cable + extension cable) may be up to 300 m.
"
Caution!
If the terminal box is installed in explosion hazardous areas, all applicable national guidelines must
be observed.
Suitable extension cables can be obtained from Endress+Hauser (s. chapter "Accessories")
Alternatively, cables with the following properties can be used:
• Number of cores according to the connection diagram (see above)
• braided wire screen for the yellow (YE) and red (RD) core (no foil screen)
• Length: up to 300 m (sensor cable + extension cable)
• Cross section: 0,75 mm
2
to 2,5 mm
2
•up to 6 Ω per core
•max. 60 nF
• for FDU91F/93/95/96 and FDU 83/84/85/86:
The earth lead must not be within the screening.