FIELD OF INVENTION
The invention relates to an improved tank cover of the power
transformer and rectifier transformers.
BACKGROUND OF THE INVENTION
Power and Rectifier transformers are housed in big boxes made of
structural steel (Mild Steel/High Tensile steel/Stain less steel),
known as tank. The active parts of the transformer viz. core coil
assembly is housed in the tank. There are primarily 2 categories of
winding High Voltage (HV) and Low Voltage (LV). The supply to the
transformer is given and taken out through HV and LV
terminations. These terminations are through bushings or cable
box. The bushing and cable boxes are normally fitted on to the
cover of the tank, which necessitates a number of large openings
(cut-outs) on the cover of the tank. Also there are other required
opening (cut-outs) on the tank cover for inspection cover, hand
holes and man-holes that are to connect the bushings
terminations inside the transformer. Besides there are opening for
tap changer and inspection covers. Thus there are 12-15 openings
on the tank cover (Fig.1). Owing to these large no. of cut-outs the
inherent strengths of the tank cover reduces drastically and the
covers tends to deform at the time of fabrication and also during
the pressure and vacuum tests. To overcome the problem,
thickness of the cover plate is required to be increased and
additional stiffeners are provided on the tank cover (which would
have been otherwise not provided).
Hence, a method is required to be devised so as to increase the
inherent strength of the tank cover. So that, the thickness of the
cover is not required to be increased and additional stiffeners can
be reduced /eliminated on this account.
OBJECTS OF THE INVENTION
An object of the invention is to propose an improved tank cover of
the power transformer and rectifier transformers.
Another object of the invention is to provide an improved tank
cover of the power transformer and rectifier transformers which is
cost effective.
Yet another object of the invention is to provide an improved tank
cover of the power transformer and rectifier transformers which
causes reduction of the leakage of the oil from the transformer
tank owing to less/no deformation (local deformation) owing to the
increase in the inherent strength of the tank cover.
Still another object of the invention is to provide an improved tank
cover of the power transformer and rectifier transformers with
reduced thickness, which is more easily available and more easily
manufacturability resulting generation of manufacturing adequacy
and reduction in time cycle of manufacturing.
STATEMENT OF INVENTION
According to this invention, there is provided an improved tank
cover of the power transformer and rectifier transformers
comprising of a turret provided on to the tank cover at cut out
wherein the turret accommodates bushings.
DETAILED DESCRIPTION OF THE INVENTION WITH
REFERENCE TO THE ACCOMPANYING DRAWINGS
The transformer is a voltage transforming machine having two
different circuits; one for incoming of the power and the other for
out going of power. The incoming/out going of power is done
through different types of terminations. The terminations used in
transformer are known as bushing. The bushing are connected to
transmission line or cable box or to the bus-duct. One end of the
bushing is connected to the windings inside the tank and the other
end of the termination is connected to the power system networks
i.e transmission line or distribution line (Fig.2). For the purpose of
fixing the bushings, cut out are provided on the tank cover (on
which the bushings are mounted). After complete manufacture of
the tank, Pressure and Vacuum test are conducted on the tank
during which the cut out parts on the tank are closed with for
example 5 mm thick plate.
The terminations viz. bushings are mounted on a small box known
as turret fixed on to the transformer tank cover at the cut out given
on the tank cover. The turret encloses the bottom part of the
bushing (known as oil side). It houses the CT (current transformer-
required for monitoring, protection and metering of the power that
is transmitted through the bushing (Fig. 3).
Under normal circumstance, the turret is a detachable part and
fixed on to the transformer tank cover at the cut out given on the
tank cover. All the bushings are fixed onto their respective turrets
mounted on their cutouts. The turret is fixed onto the tank during
factory testing and then removed. So that, the transportation
height of the transformer reduces during shipment to site. After
the transformer reaching at site, the turret (which is sent
separately) is fixed on to the tank cover.
The turret may be welded on to the tank cover for conducting the
testing on the tank with turrets welded. The welded turret acts as
virtual stiffeners for the tank cover. As such all the turrets
mounted on the cut out of cover acts as stiffeners and thereby the
inherent strength of the tank cover is increased (Fig. 4).
The welding of the turret invariably increases the shipping height
(height of the transformer during transport to site) of the
transformer and in some case may create problem in
transportation. In such cases the turret is bifurcated into two
parts, the bottom part is welded to the tank and the top part of the
turret is detachable. The bottom part is bolted onto the top part of
the turret at site upon arrival of the transformer (Fig. 5).
It is to be noted that the present invention is susceptible to
modifications, adaptations and changes by those skilled in the art.
Such variant embodiments employing the concepts and features of
this invention are intended to be within the scope of the present
invention, which is further set forth under the following claims:-
WE CLAIM:-
1. An improved tank cover of the power transformer and
rectifier transformers comprising of a turret provided on to
the tank cover at cut out wherein the turret accommodates
bushings.
2. An improved tank cover of the power transformer and
rectifier transformers as claimed in claim 1 wherein the
turret encloses the bottom part of the bushing, which houses
the current transformer- required for monitoring, protection
and metering of the power transmitted through the bushing.
3. An improved tank cover of the power transformer and
rectifier transformers as claimed in claim 1 or 2 wherein the
turret is detachable.
4. An improved tank cover of the power transformer and
rectifier transformers as claimed in any of the preceding
claims wherein the turret is fixedly provided on the cover.
5. An improved tank cover of the power transformer and
rectifier transformers as claimed in any of the preceding
claims wherein the turret is bifurcated into two parts, the
bottom part is welded to the tank and the top part of the
turret is detachable.
6. An improved tank cover of the power transformer and
rectifier transformers substantially as herein described with
reference to the accompanying drawings.

This invention relates to an improved tank cover of the power
transformer and rectifier transformers comprising of a turret
provided on to the tank cover at cut out wherein the turret
accommodates bushings.