Connection Routing; Surface Preparation - Siemens GEAFOL Operating Instructions Manual

GEAFOL- / CARECO-Cast-resin Transformer/ Operating Instructions
Connecting
CAUTION!
Do not climb on connecting tubes of the transformer at
connecting!
CAUTION!
Metallic objects in the coils can destroy the transformer!
The coils must be covered during connection.

Connection routing

6.1
Cast resin transformers allow many connection combina-
tions, both from above and below.
When connecting cables are use, make sure that they fea-
ture adequate strain relief and are routed so that the volt-
age clearances are maintained in line with relevant regula-
tions.
The minimum clearances for cable connections shown in
Table 5.1 and Fig. 5.10 must be observed.
Connection of high voltage
6.2
(HV)
On the high-voltage side, the transformer is connected to
the surfaces of the delta connecting tubes or the terminals
provided on the casted delta connection bar, or to the cast-
on post insulators on the high-voltage pottings (Y connec-
tion).
A Connection of low voltage
6.3
(LV)
On the low-voltage side, the transformer is connected to
the aluminum terminals provided for this purpose. Here
again it must be ensured when connecting cables, that
they feature adequate strain relief to avoid undue mechan-
ical stress at the terminals. The following guidelines must
be observed when connecting the transformer terminals
via expansion straps.
If the low-voltage connection is established with busbars,
an expansion strap (flexible connection element) must be
installed between the transformer and the busbars. This
keeps mechanical stresses away from the transformer (see
Fig. 6-2) and largely prevents transmission of structure-
borne transformer noise. Detailed information on bolted
busbar connections can be found in DIN 43673.
Fig. 6-1: Example of connection
Fig. 6-2: Low-voltage end connection with expan-
sion strapp

Surface preparation

6.4
Before making any bolted or terminal connections, it is
necessary to remove the thin, invisible layer of oxide,
which is a poor conductor of electricity, from the alumi-
num surface. Therefore, the contact surfaces to the cus-
tomer connections must be made metallically bright. Every
time a point of contact is opened, the aluminum contact
surface must be subjected to the full preparation process
again before it is bolted back together.
© 2021 Siemens Energy Page 14