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30
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!
Undo right-hand bolt at the joint
s
and fold the earthing busbar section
a
to the left
into horizontal position.
!
Bolt the earthing busbar section
a
together with the earthing busbar of the next
transport unit using 2 bolts. Tightening torque: 70 Nm.
!
Refit the removed bolt at the joint
s
and tighten the two bolts at the joint.
Tightening torque: 70 Nm.
!
Proceed in the same way with all other transport units until all earthing busbar ends
of the switchgear are interconnected.
Earthing the panels
!
Connect the earthing busbar to the station earth.
Recommendation:
In case of panel groups, earth the end panels and every fifth
panel at least.
8
Installation work with SF
6
-gas before commissioning
If a rated short-duration power-frequency withstand voltage test has to be carried out at
site, the work with insulating sulphur hexafluoride gas (SF
6
) described in this section
must be performed in advance.
8.1
Completing busbar assembly and filling with SF
6
-gas
The individual phases and sections of the busbar (called
busbar runs
hereafter) must be
filled with SF
6
-gas at site. Each busbar run forms one gas compartment.
Busbar runs within one transport unit that are already filled and closed hermetically at
the factory
are not refilled with SF
6
-gas at site.
All parts of the switchgear that have to be filled with gas are equipped with desiccant
bags in order to eliminate residual humidity in the gas filling. In ambient air, the desiccant
agent loses its effectiveness rapidly.
To expose the desiccant bags as briefly as possible to the ambient air, the following
installation and gas work is performed
completely on one busbar run
, and is then
continued on the next busbar run, etc.
DANGER!
SF
6
-gas is heavier than air and concentrates first near to the floor and in floor openings.
Danger of suffocation!
!
Do not let SF
6
-gas get into the environment.
!
While working with SF
6
-gas, provide for sufficient ventilation.
!
After working with SF
6
-gas, vent the cable basement and any hollows in the floors
with special care.
!
Observe the safety data sheet for SF
6
-gas.