FIELD OF THE INVENTION
The present invention relates to a technique to enhance reliability and availability
of power supply through continuous drying out of contaminated oil in power
transformer. More particularly, the invention relates to an improved thermo
siphon filter device for continuous filtering of contaminated transformer oil.
BACKGROUND OF THE INVENTION
A power transformer is a machine for transforming large amount of energy
(power). The transformer comprises a magnetic circuit known as core, and two
different insulated coils one each for incoming and outgoing of the power. The
core and the coils are insulated from each other by providing insulating material.
The core-coil assembly is kept inside a metallic vessel known as tank. The
transformer tank is always maintained completely full of oil.
During operation of the transformer, heat is generated and temperature of the
transformer goes up. With increase of the temperature, water particles are
released from the insulations of the transformer. These water particles get
mixed-up into the oil. If these water particles are not removed from oil, the oil
quality deteriorates and the electrical strength of the oil reduces which ultimately
leads to failure of the transformer in service. To prevent the failure of the
transformer, the transformer is shut down for maintenance (causing interruption
in power supply). During maintenance of the transformer, oil of the transformer
is taken out from the transformer, dried and re-filled into the transformer.
Hence, it is essential continuously to remove water particles from the oil. For this
purpose, according to the prior art, a Thermo Siphon Filter is used. The thermo
siphon filter consists of a container filled with Dry Alumina. The hot oil resulted
from working of the transformer, carries the water particles (moisture) and flows
through this container and comes in contact with the Alumina. The Alumina
absorbs the water from the oil. Thus, the oil of the transformer gets continuously
dried.
In the process, the Alumina absorbs water particles and reduces it's effectiveness
gradually. It is therefore essential to take out the Alumina from the Thermo
Siphon container and dry them separately. For this purpose, the Thermo-siphon
filter is removed from the service and drying out of the hot oil from the
transformer gets interrupted till the dried Alumina is again filled into the filter.
Hence, a method is necessary to avoid interruption during the process of drying
out of the Alumina of the Thermo siphon, even when the Thermo siphon filter
remains disposed on the transformer.
OBJECTS OF THE INVENTION
It is therefore, an object of the invention to propose an improved thermo siphon
filter device for continuous filtering of contaminated transformer oil.
Another object of the invention is to propose an improved thermo siphon filter
device for continuous filtering of contaminated transformer oil, which enables un-
interrupted operation of the transformer.
A still another object of the invention is to propose an improved thermo siphon
filter device for continuous filtering of contaminated transformer oil, which allows
drying of the filtering the Thermo siphon filter of the transformer without
periodical de-commissioning of the filter.
A further object of the invention is to propose an improved thermo siphon filter
device for continuous filtering of contaminated transformer oil, which eliminates
frequent removal of the Thermo siphon filter from the transformer for drying the
filtering media.
A still further objection of the invention is to propose an improved thermo siphon
filter device for continuous filtering of contaminated transformer oil, which
reduces the over ail mounting space of the filter device on the transformer.
SUMMARY OF THE INVENTION
Accordingly, there is provided an improved thermo siphon filter device for
continuous filtering of contaminated oil in operating power transformers to
provide un-interrupted power supply, the device comprising a metallic container
allowing passage of contaminated transformer oil for separation of water
particles including associated impurities from the oil, a pair of valve means for
allowing passage of contaminated oil from inside the power transformer to the
thermo siphon filter device, and flow of filtered oil from the fitter device to the
transformer, the improvement is characterized in that, a plurality of removable
perforated trays forming a stack, each tray accommodating an adsorbent and
disposed one above the other, the removable perforated trays being interposed
in said metallic container such that the contaminated oil passes through the
perforated trays containing the adsorbent and allows a continuous filtering of the
oil.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE
INVENTION
A prior art thermo siphon filter (TSF) provided on a transformer tank (1) is
shown in fig.l. The thermo siphon filter (TSF) consists of a metallic container (2)
filled with Dry Alumina (3). The hot contaminated oil (8) from the transformer
flows through this container (2), and comes in contact with the Alumina (a
chemical substance that absorbs water particles from transformer oil). The
Alumina (3) absorbs the water from the oil and the oil becomes dry. Thus, the oil
of the transformer gets continuously dried, but the Alumina becomes wet and
after some time, it becomes in-effective. According to prior art, the wet alumina
is taken out and processed for drying periodically in order to retain substantially
the original property of the alumina. For taking out the Alumina (3) for drying
out, the thermo siphon filter (TSF) has to be de-activated by closing valve means
(4, 7), causing an interruption in drying of the oil.
To mitigate the problem, an improved thermo siphon filter as shown in Fig.2, is
provided. According to the invention, the container (2) of the thermo siphon filter
(TSFi) is equipped with a plurality of removable perforated trays (5). The
removable perforated trays (5) are attached to the container (2) of the thermo
siphon filter (TSFO/ one above the other. The perforated trays (trays having a
number of small holes at their base) are filled with Dry Alumina (3). Hot oil (8)
from the transformer is allowed to pass through the perforated trays (5) and
comes in contact with the Dry Alumina (3). The Alumina (3) absorbs moisture
(water particles) from the oil (8). The oil moves from one perforated tray (5) to
the other perforated tray (5) through the perforations (6). In each perforated
tray (5) the oil comes in contact with the Alumina (3) and gets dried. The
perforated trays (5) are disposed one above the other and fitted inside the
container (2) in a removable way i.e. any of the perforated tray (5) can be
removed from the container (2), without disturbing the other perforated trays
(5). All the trays (5) are filled with Alumina (3). Accordingly, wet alumina of a
removed perforated tray (5) is externally dried out and replaced with dried
Alumina. Thus, the Thermo siphon filter (TSF1) always remains operative with
the retained trays functioning effectively. Alternatively, additional perforated
trays (5) with dry alumina (3) may be maintained as buffer to instantaneously
replace the removed tray. In this way, the invention ensures that the Thermo
siphon filter is not de-commissioned from service. Thus, the oil of the
transformer gets continuously dried and an un-interrupted service of the Thermo
siphon filter is made available for drying out the oil during the operation of the
transformer. Because of this improved configuration of the thermo siphon filter,
contamination of the transformer oil is reduced, which inter-alia lessens shut
down of the transformer thereby, providing increased availability of the
transformer including power supply. The container (2) comprises a door (11),
and a handle (10) is provided to remove/replace of the perforated trays (5).
ADVANTAGES OF THE INVENTION
1. The present invention enhances the reliability and availability of power
supply by continuously improving the quality of oil in a running
transformer through un-interrupted service of the thermo-siphon filter
device.
2. The filter device of the invention allows reduction in the break down time
and cost for maintenance of the transformer including transformer oil.
3. The present invention makes it possible for the Thermo siphon filter of the
transformer, to provide an un-interrupted drying capability, and thereby
increase the reliability and longevity of the transformer by continuous
drying of oil.
4. The invention reduces the over all cost of the transformer by eliminating a
stand-by thermo siphon filter, simultaneously providing un-interrupted
service for drying out of oil.
WE CLAIM
1. An improved thermo siphon filter device (TSFi) for continuous filtering of
contaminated oil (8) in operating power transformers to provide un-
interrupted power supply, the device comprising:
- a metallic container (2) allowing passage of contaminated
transformer oil to the filtering media of the device for separation of
water particles including associated impurities from the oil;
- a pair of valve means (4, 7) allowing egress of contaminated oil (8)
from inside the power transformer to the thermo siphon filter
device (TSF1), and ingress of filtered oil from the filter device to the
transformer;
the improvement is characterized in that:
- a plurality of removable perforated trays (5) forming a stack, each
accommodating an adsorbent (3) and disposed one above the
other, the removable perforated trays being interposed in said
metallic container (2) such that the contaminated oil (8) passes
"through the perforated trays (5) containing the adsorbent (3) and
allows a continuous filtering of the oil (8).
2. The device as claimed in claim 1, wherein the perforated trays (5) are
provided with a plurality of holes (6) to form a passage for the
contaminated oil (8).
3. The device as claimed in claim 1, wherein the absorbent may be selected
as dry alumina (3).
4. The device as claimed in claim 1, wherein the perforated trays (5) are
removable and replaceable during operating mode of the transformer.
5. The device as claimed in any of the preceding claims, wherein the
adsorbent can be dried and replaced back in each perforated trays.
6. An improved thermo siphon filter device (TSF1) for continuous filtering of
contaminated oil (8) in operating power transformers to provide un-
interrupted power supply as substantially described and illustrated herein
with reference to the accompanying drawings.

ABSTRACT

The invention relates to an improved thermo siphon filter device (TSF1) for
continuous filtering of contaminated oil (8) in operating power transformers to
provide un-interrupted power supply, the device comprising a metallic container
(2) allowing passage of contaminated transformer oil for separation of water
particles including associated impurities from the oil, a pair of valve means (4, 7)
for allowing egress of contaminated oil (8) from inside the power transformer to
the thermo siphon filter device (TSF1), and ingress of filtered oil from the filter
device to the transformer, the improvement is a plurality of removable
perforated trays (5) forming a stack, each tray accommodating an adsorbent (3)
and disposed one above the other, the removable perforated trays being
interposed in said metallic container (2) such that the contaminated oil (8)
passes through the perforated trays (5) containing the adsorbent (3) and allows
a continuous filtering of the oil (8).