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Connecting
7.4 Connecting the functional ground
PN/M-Bus LINK
32
Operating Instructions, 03/2018, A5E44260928-AA
Connector pin assignment
The figure below shows the assignment of the terminal for the 24 V DC power supply.
Table 7- 1
Terminal assignment for the 24 DC power supply
L+
24 V supply for PN/M-Bus LINK (+)
M
24 V supply for PN/M-Bus LINK (-)
Functional ground
Permissible torques for screw terminal:
●
Minimum tightening torque: 0.5 Nm
●
Maximum tightening torque: 0.6 Nm
External lightning protector
An external lightning protector can be installed in the 24 V DC supply line to protect against
powerful pulses on the supply lines:
We recommend the Dehn Blitzductor BXT ML2 BD 180, article number 920 247 (on basis
BXT BAS) or an equivalent protection element.
Manufacturer:
DEHN+SOEHNE GmbH+Co.KG, Hans-Dehn-Str.1, Postfach 1640, 92306 Neumarkt,
Germany. The lightning protection module must be installed and used in accordance with the
manufacturer's specifications.
7.4
Connecting the functional ground
Connect the ground (e.g. from mounting rail) for discharge of EMI, such as bursts or surges,
to the FE terminal (see Connecting 24 V DC (Page 31)).
Permissible conductor cross-section:
●
0.5 - 6 mm², AWG 26 - AWG 12
Note
EMC-compliant functional grounding
•
Use as short a stranded-wire conductor as possible with a large cross section.
•
Compliance with the technical specifications of the device is only assured with a correct
functional ground connection.
Also see information and notes on shielding in the section Power supply and potential ratios
(Page 28).