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Note: The assembly of busbars is carried out with
"stabilized connections"; meaning that quality of
busbar joints does not significantly change over
period of operating time and therefore it is not
necessary to inspect tightness of busbar
connections at frequent intervals, but upon the
condition that correct assembly is carried out
as described in preceding paragraphs and with
paying due attention to the following:
•
The overlapping surfaces are cleaned
thoroughly with a brass wire brush to remove
oxidized surface (skin).
•
Wiped clean with metal free non-woven cloth.
•
Greased evenly with a thin coat of
SETRAL EK 339 or equivalent.
•
Prescribed torque is applied during tightening
of the joint using a calibrated torque wrench.
CAUTION!
Use proper personal protective
equipment like hand gloves, helmets
and etc., while handling switchgears.
UniGear ZS2 switchgears have a copper bar for
the earth system. The main earth bar is of
standard length and is located at the bottom of
switchgear. While coupling UniGear ZS2
switchgears during erection, the earth bar shall
also be connected with the earth bus of the
adjoining switchgear using the copper link
provided at the same location. Conical washers to
ABB standard 9ADA334 are recommended to be
used throughout the earth bar connections.
The earthing busbar now connected and running
through all switchgear shall be connected to the
station's earth system. Copper bars used for
earthing Aluminium Zinc coated steel plate must
be greased (type E) to avoid galvanic corrosion.
32x8 mm Cu Bridge
assembled at site
—
Figure 46 - Main earthing busbar assembly
6.2 Cable connection
6.2.1 Power cables
The standard method for terminating power
cables in UniGear ZS2 switchgear is shown in
Fig.47. Power cables are conveyed below through
floor covering gland plate, which can be adapted
to the required cable diameter. Cables can be
securely fastened to the cable holding bracket in
the switchgear by means of using clamps.
Cable termination kits are mounted on cable
cores according to manufacturer's instructions
considering cable termination height, and it also
recommended to maintain uniform lengths of
cable ends, including cable termination kits.
Cable connection terminals from current
transformers have different versions like: for
different number of parallel cables, for different
rated currents, and short circuit currents.
Current transformers connections are equipped
with the holes for M12 bolts. The earthing of cable
armour is carried out by connecting it to the
cable holding bracket connected to earth
potential.
The cable compartment can also be made to
accommodate withdrawable type potential
transformers fitted with HRC fuses or mounting
of surge arresters. In these cases, the number of
parallel cables that can be accommodated in
cable compartment gets reduced.
Note: Cable glands or clamps and grommet are
not considered in the scope of ABB.
Connected to the
earthing switch
37
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