Shielding And Grounding - Endress+Hauser OTMT84 Bedienungsanleitung

Dual-input temperature transmitter
Grounding via one of the grounding screws (terminal head, field housing) is
recommended.
4.3.1 Cable glands or entries
Fig. 7: Connection to the fieldbus cable - installed in the field housing on the left, and in the terminal head on the right
1 Fieldbus terminals - fieldbus communication and power supply
2 Inner ground terminal
3 Outer ground terminal
4 Shielded fieldbus cable
‣
The terminals for the fieldbus connection (1+ and 2-) are not polarity sensitive.
‣
Conductor cross-section:
2
– Max. 2.5 mm for screw terminals
2
– Max. 1.5 mm
for spring terminals. Stripping length of wire = min. 10 mm (0.39 in)
‣
A shielded cable must be used for the connection.

4.3.2 Shielding and grounding

Optimum electromagnetic compatibility (EMC) of the fieldbus system can only be guaranteed if
the system components and, in particular, the lines are shielded and the shield forms as
complete a cover as possible.
The fieldbus system allows three different types of shielding:
• Shielding at both ends.
• Shielding at one end on the feed side with capacitance connection to the field device.
• Shielding at one end on the feed side.
With regard to EMC, the best results are achieved in most cases with one-sided shielding on the
feed side (no capacitance connection to the field device). Operation in the event of disturbance
variables as per NAMUR NE21 is thus guaranteed.
Wiring
A0008284
35