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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
2
-section. The
earthing busbar joints must be connected to the
coupling points of the switchgear unit groups,
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.
Figure 85: Primary earthing busbar (ENA version).
Figure 86: Primary earthing busbar (IEC version).
1 Copper base earthing busbar
2 Screw
3 Washer
4 Fixing bolt
6.7.2 Switchgear earthing connection (Figure 85),
(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 be tightened with the
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 possible 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.
6.7.3 Secondary earthing busbar (ENA version
only) (Figure 87).
ENA version switchgear is equipped with an additional
secondary earthing busbar which runs along the
switchgear in the bottom part of the low voltage
compartment. Connections must be made as
described above for primary earthing busbar and with
reference to (Figure 87).
Figure 87: Secondary earthing busbar (ENA version only).
1 M8 x 20 (4 x) screws with washer
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
and earthing system. Tighten if required.
Thoroughly clean the switchgear.
Remove all foreign bodies from the panels.
Correctly replace all coverings, etc. removed
during erection and connection.
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.
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