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4.4 Foundations
4.4.1 Foundation types
General aspects
The switchgear must be erected on a foundation that fulfils the
requirement of a 2 mm maximum horizontal height deviation
in relation to the length and diagonal of the switchgear. As it
is difficult to make a concrete foundation that fulfils the above
levelness requirement, adjustments are made using a metal
frame or by installing steel plates under the corners of the
units. The load capacity of the floor and foundation must also
be sufficient.
Figure 35. Switchgear erected on a metal frame
Figure 36. Switchgear erected on a floating floor
If the switchgear only consists of a few units and no heavy units
are included, it can be installed on the concrete floor.
Figure 37. Switchgear installed on a concrete floor
4.5 Installation procedure for units
4.5.1 Assembly of the first two switchgear units
WARNING
Before positioning the different switchgear
units, check the floor levelling, with par-
ticular attention to the longitudinal flatness
(maximum levelness 2/1000).
NOTE
If horizontal gas vent ducts are provided,
mount the joint brackets unit by unit right
from the start (see 4.6.2).
4.5.2 Removing roof plates
Plate dismantling is carried out as follows:
a) Unscrew the screws present at both ends of the roof.
b) Remove the plate.
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