Installation and Connections
35
8.5.3 Interconnecting the Earth Terminals of Multiple Switchgear Cabinets
The earth must be with less interference voltage as possible. If this cannot be achieved, a se-
parate earth for the control has to be installed.
Figure 10: Connection of earth terminals
8.6 Shielding of Data Lines in the HIMA Communication Systems
Reliable shielding of data lines in HIMA communication systems is achieved by the following
measures:
The connection
1
) of the cable shield from the bus subscriber’s (H41q, H51q) to the bus termi-
nals (H 7506) is established on the bus subscriber’s side. Via the plug case and the metal front
plate a connection is established via the PCB layout to the PE cabinet earth. The other side of
the cable shield is not connected.
The connection
2
) of the H 7505 interface converter is also established on one side via the plug
case. The connection to the top hat rail is established via the X2/1
5
) connection. According to
HIMA earthing principles the top hat rail itself is connected to the cabinet earth or optionally, to
an instrument earth
6
).
The connection
4
) of the cable shield between the individual H 7506 bus terminals is estab-
lished on one side via a terminal. The terminal is located on a top hat rail to which it is also
conductively connected.
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