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Earthing
Earthing the Bus Cable
Screens
Termination: ON
NCSA-01 Installation and Start-up Guide
The NCSA-01 module earth is connected to the rail onto which the
module is mounted. If the rail is fastened to an earthed metallic
assembly plate, the module is automatically earthed, and no external
earthing wire is needed. If the rail is fastened to a base that is not
earthed, the rail must be connected to the nearest earthing terminal.
However, the earthing wire should not be connected to the same
terminal as the power cable screens. (See page 3-1.)
The NCSA-01 module has several built-in earthing terminals (see
Figure 4-4):
• The PE terminal is internally connected to the NCSA-01 module
earth. Normally, no external wires need to be connected to this
terminal.
• The SH terminal is internally connected to the NCSA-01 module
earth. The SH terminal is normally used for earthing the bus cable
shield if there is no other station at which the cable shield is directly
earthed.
• The SHF terminal is internally connected to the NCSA-01 module
earth via an RC filter. The SHF terminal is typically used for earthing
the bus cable shield.
• The DG terminal is isolated from the NCSA-01 module earth. This
terminal is to be connected to the SHF terminal on each module (as
shown in Figure 4-4 below) in order to provide a common reference
potential to all modules on the bus.
The bus cable screen may be directly earthed at one station only. At
other stations the cable screen should be earthed via an RC filter. A
wiring example in given below.
CS 31 Master
Figure 4-4 CS 31 bus cable connection.
4
3
2
1
2
X
01
NCSA-
100 Ω
[Station 1]
Termination: OFF
Chapter 4 – Electrical Installation
4
3
2
X
100 Ω
...
Termination: ON
2
1
01
NCSA-
[Station N]
4-3
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