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6.7 Earthing circuit
6.7.1 Primary earthing busbar
All the switchgear cubicles are equipped with a copper
base earthing busbar 1 with a 240 mm
earthing busbar joints must be connected to the
coupling
points
of
removing any oxidation traces from the busbar contact
surface beforehand by means of an emery cloth.
The earthing busbar joint between the units is made
using screws 2, washers 3 and a nut. The tightening
torque to be applied is 75 Nm.
F i g u re 85 : Pri mary earth i n g b u sb ar (EN A v ersi o n ).
F i g u re 86: Pri mary earth i n g b u sb ar (I EC versi o n ).
1
Copp er bas e eart hi ng bus bar
2
Screw
3
W asher
4
F ixing bo lt
6.7.2 Sw itchgear earthing connection
(Figure 86)
The earthing busbar runs longitudinally along the rear
bottom part of the whole switchgear. A fixing (4) bolt
is used for connecting the earthing network. The
screws
and
bolts
must
prescribed torque value to prevent any loosening due
to operating vibrations.
The position of the connection to the apparatus
earthing network is shown in the project drawings.
The earthing connection must at least be made on the
two switchgear ends, be as short as p ossible and must
not run in metallic tubes. The earthing conductor must
be manufactured so as to withstand the maximum
earth fault current foreseen. Generally, this conductor
must not have a cross -section smaller than that of the
switchgear earthing busbar .
46
2
-section. The
the
switchgear
unit
(Figure
be
tightened
with
6.7.3 Secondary earthing busbar (ENA version
only)
(Figure
ENA version switchgear is equipped with an additional
secondary earthing busbar which runs along the
groups,
switchgear in the bottom part of the low voltage
compartment.
described above for primary earthing busbar and with
reference to
F i g u re 87: Seco n d ary ea rth i n g b u sb ar (EN A ver si o n o nl y).
1
M8 x 20 (4 x) screws w it h wash er
6.8 Final erection work
Check painted areas of the switchgear for possible
damage and touch up where required.
Check bolt connections, in particular all those
made during the on -site erection of the busbars
85),
and earthing system. Tighten if required.
Thoroughly clean the switchge ar.
Remove all foreign bodies from the panels.
Correctly
during erection and connection.
the
In the enclosure, any remaining openings must be
closed if they are no longer needed.
Operationally moveable parts for ease of motion, if
necessary relubricate with SYN-setral-EK 339.
87).
Connections
must
(Figure
87).
replace
all
coverings,
be
made
as
etc.
removed
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