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Instruction Manual
2. DESIGN AND CONSTRUCTION
2.1. Construction and primary circuit
The
active
transformer is located below the
porcelain insulator and the current
transformer part above. The primary
circuit is short, rigid and straight,
minimizing heating. In addition, it
withstands
electrodynamics
more
easily,
performance,
electrodynamics and thermal effects, in
a presence of short-circuit currents.
Primary series and parallel connections
with external links (for reconnection 1:2
or 1:2:4) or, if necessary, n-turn (more
than 4 turns) designs can be provided.
This arrangement allows also better
accuracy in transient conditions.
The primary terminals are directly
connected to the conductor.
Attention! Do not lift the unit at the
primary terminals or remove the
primary terminals!
2.2. Secondary circuit
Related to the CT's active part, the
toroidal
ferromagnetic
manufactured either from very high
permeability grain-oriented steel or
from specialized alloys. In order to
achieve
a
behavior, protection cores can also be
provided with gaps.
All secondary windings are enclosed in
an aluminum box which protects them
against high frequency disturbances
while acting as a low voltage shielding
© GE Grid Solutions
part
of
the
voltage
forces
allowing
high
level
related
cores
satisfactory
transient
electrode.
extended up to the base by an aluminum
tube which contains all secondary leads.
The
connections is designed to support fault
currents.
The bottom of the hermetic and
watertight secondary terminal box is
closed by a fitted plate, with or without
cable gland depending on customer
requirements.
to
2.3. Paper-oil insulation
The active part of the transformer is
insulated by a vacuum impregnated
oil/paper system. Degassed and filtered
mineral oil is used and is heated before
filling
impregnation. It is an insulating oil with
excellent
absorbing properties. It does not
contain any Polychlorinated Biphenyl
(PCB).
2.4. Oil volume compensation system
To protect the oil from the environment,
the CT head is sealed by a metallic
bellows. The bellows assembly provides
pressure compensation for temperature
are
variation and allows the transformer to
work virtually free of over-pressure.
The bellows resists aging and corrosion.
IF THE HERMETIC SEAL OTHER THAN
DURING OIL SAMPLING IS BROKEN,
CONTACT
IMMEDIATELY.
An oil level indicator is provided and is
scaled to show the oil level over the
This
aluminum
cross
section
of
to
provide
aging
stability
THE
MANUFACTURER
box
is
the
earth
maximum
and
gas
6
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