FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
As amended by the Patents (Amendment) Act, 2005
&
The Patents Rules, 2003
As amended by the Patents (Amendment) Rules, 2006
COMPLETE SPECIFICATION (See section 10 and rule 13)
TITLE OF THE INVENTION
A streamlined radiator unit for cooling of transformer oil
APPLICANT
Crompton Greaves Limited, CG House. Dr Annie Besant Road, Worli, Mumbai 400 030,
Maharashtra, India, an Indian Company
INVENTORS
Paramane Sachin Bhimarao; Jain Prateek Kumar; Prabhu Nishikant Madhusudan; Joshi Kishor Uddhav; Srinivas Dhavileswarapu; all of Analytics Centre, Global R&D, Crompton Greaves Ltd., Kanjurmarg (East), Mumbai- 400042 Maharashtra, India, all Indian Nationals
PREAMBLE TO THE DESCRIPTION
The following specification particularly describes the invention and the manner in which it is to be performed:

FIELD OF THE INVENTION
The present invention relates generally to cooling of transformer oil flowing
therethrough and more particularly to, cooling of transformer oil via radiator units coupled with such transformers.
DESCRIPTION OF THE BACKGROUND ART
Large or small power transformers are typically used either to step up or to step
down the voltages during power transmission depending on the need of transmission. Rated output of such transformers can go upto several hundred KVs and therefore they generate substantial amount of heat energy during operation. Various kinds of known dielectric fluids /transformer oils are used within the transformers to perform various known functions among which prominent being keeping the heat energy levels down at a particular level and to dissipate heat during prolong operation of the transformer. However, after sufficient time such dielectric fluids transformer oils also become hot and therefore start to lose their heat dissipation properties, which if not restored can damage the transformer reducing its life expectancy. So, such transformer oils are cooled dynamically through radiator units commonly installed within or outside transformers.
Natural cooling of dielectric fluids /transformer oils used within the transformers
is one way of cooling these. Another manner in which the dielectric fluids/transformer oils are cooled is by forced cooling of cooling dielectric fluids/transformer oils. Radiators or coolers using airflow are installed along with the transformers for forced cooling. The airflow is generated by fans installed with such radiators/coolers. Typically, the fans are installed below the radiators/coolers and the transformer oil is allowed to pass through such radiators/coolers opposite to the direction of the generated airflow. Due to heat exchange between the relatively

low temperature airflow and the high temperature dielectric fluids /transformer oils, the dielectric fluids /transformer oils are cooled and again introduced within the transformers.
Forced cooling via radiators and fans has some drawbacks noted below that need
immediate attention. Presently, in most of the transformer radiators, which comprises of several radiator plates, these radiator plates are positioned in vertical direction. The generated air flow from the fan directly hits the vertical plates at an acute angle and causes resistance to the airflow and results in the back flow of air. This results in wastage of airflow that tries to escape from the sideways of the radiators. Additionally, as the entry of air to the radiator is not smooth it increases the noise level of the transformer.
Thus, there is a need to devise radiator units that addresses at least some of the
above mentioned drawbacks yet providing effective cooling to the dielectric fluids/transformer oils are used within the transformers.
SUMMARY OF THE INVENTION
Accordingly disclosed herein is a radiator unit couplable with an inlet and an
outlet of a transformer housing for cooling of transformer oil flowing through a transformer including, a distributor header and a collector header coupled with the inlet and the outlet of the transformer housing, respectively, the distributor header and the collector header including a plurality of spaced apart openings formed along a circular portion of the distributor and collector headers, a plurality of radiator plates vertically disposed in spaced apart relationship with each other and arranged in a circular configuration, each of the radiator plates extending between a pair of opposite ends and having atleast one internally formed passage that extends to open at the opposite ends, opposite ends of each of the radiator plates connected between the distributor and the collector headers and aligned with the a corresponding opening of the distributor and the collector headers, and an axial flow fan positionable proximal to the plurality of radiator plates to

generate air flow that passes along the length of each of the radiator plates, one of the opposite ends and a sufficient portion adjacent to the opposite ends of each of the radiator plates streamlined with an outlet angle of the generated air flow.
In several embodiments, each of the radiator plates has an oblong cross-sectional
area, and wherein each of the radiator plates are bundled together and arranged in the circular configuration.
In several embodiments, each of the radiator plates have a linear cross-sectional
area, and wherein width of each of the radiator plates nearer to the axial flow fan is shorter than the width of each of the radiator plates distant from the axial flow fan.
In several embodiments, the distributor and collector heads are formed to have a
circular cross-section, and wherein the opposite ends of each of the radiator plates has a semicircular cut-out portion to expose the at least one passage, the semi-circular cut-out portions fitted to the distributor and collector heads, respectively, to allow the at least one passage to be aligned with the corresponding openings of the distributor and collector heads.
It is to be understood that both the foregoing general description and the
following detailed description of the present embodiments of the invention are intended to provide an overview or framework for understanding the nature and character of the invention as it is claimed. The accompanying drawings are included to provide a further understanding of the invention and are incorporated into and constitute a part of this specification. The drawings illustrate various embodiments of the invention and together with the description serve to explain the principles and operation of the invention.

A BRIEF DESCRIPTION OF THE DRAWINGS
The above-mentioned and other features and advantages of the various
embodiments of the invention, and the manner of attaining them, will become more apparent and will be better understood by reference to the accompanying drawings, wherein:
FIG. 1 is a front elevational view of a radiator unit coupled with a transformer
housing shown in partial cut-sectional view according to an embodiment of the present invention;
FIG. 2 is a perspective view of the radiator unit of FIG. 1;
FIG. 3 is an inside view of a distributor/collector header of FIG. 2 according to an
embodiment of the present invention;
FIG. 4 is a perspective view of a radiator plate showing a plurality of internally
formed passages extending between a pair of opposite ends and used to form the radiator unit of FIG. 2 according to an embodiment of the present invention;
FIG. 5 is a zoomed-in perspective view of one of the opposite ends of a radiator
plate of FIG. 4;
FIG. 6 is a bottom view of the radiator unit of FIG. 1;
FIG. 7 is a perspective view of an airflow simulation generated from an axial flow
fan that is coupled to the radiator unit of FIG. 1;
FIG. 8 is a perspective view of a radiator unit according to another embodiment of
the present invention coupled with the transformer housing of FIG. 1; and
FIG. 9 is a perspective view of a radiator plate used to form the radiator unit of
FIG. 8 according to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
FIG. 1 illustrates a radiator unit 100 that may be coupled to a transformer 102
according to an embodiment of the present invention. The transformer 102 includes a transformer housing 104 shown in a partial cut-sectional view and includes an inlet 106 and an outlet 108. The transformer housing 104 includes well known transformer oil that dynamically circulates (shown in arrows) through transformer windings 110 to provide the desired cooling effect, whose temperature increases after a prolong operation. As the high temperature transformer oil needs to be cooled, the transformer oil is introduced into the radiator unit 100 through the outlet 108 where forced cooling of the transformer oil takes place. The cooled transformer oil within the radiator unit 100 then enters within the transformer housing 104 via the inlet 106 within the transformer housing 104.
FIG. 2 shows a perspective view of the radiator unit 100 and includes a distributor
header 112 and a collector header 114 that may be coupled with the inlet 106 and the outlet 108 of the transformer housing 104, respectively (See FIG. 1). An elongated portion 116 of the distributor header 112 is mechanically coupled, preferably through a coupling 118, to the outlet 108 of the transformer housing 104 whereas an elongated portion 116 of the collector header 114 is coupled to the inlet 106 of transformer housing 104. Preferably, both the distributor header 112 and the collector header 114 also have a substantially circular portion 120 and are formed to have a preferably circular cross-section. FIG. 3 shows an inside view of a distributor/collector header 112, 114 according to an embodiment of the present invention. As seen, the distributor/collector header 112, 114 has a plurality of spaced apart openings 122 formed on the inside surface of the distributor/collector headers 112, 114. It is through these openings 122 that the transformer oil, received within the distributor header 112, is allowed to enter within the radiator unit 100 whereas the cooled transformer oil from the radiator unit 100 is received within the collector header 114 to be further introduced within the transformer windings 110 of the

transformer housing 104. Further, as shown in FIG. 2, a plurality of radiator plates 124 are vertically disposed in spaced apart relationship with each other and arranged in a circular configuration. Preferably, as shown in FIG. 2, the plurality of radiator plates 124 is arranged in an oblong configuration. It is to be noted that various other configurations may also be possible and considered to be within the scope of the present invention. The plurality of radiator plates 124 is connected with the distributor header 112 and extends to be connected with the collector header 114 without departing from the oblong configuration of the plurality of radiator plates 124.
FIG. 4 shows a perspective view of an isolated radiator plate 126 according to an
embodiment of the present invention. The radiator plate 126 extends between a pair of opposite ends 128 and formed to have an oblong cross-section therebetween. Further, each of the radiator plates 126 has a semi-circular cut-out portion 130 at each of the opposite ends 128. Furthermore, each of the radiator plates 126 include at least one internally formed passage 132 that extends between both the opposite ends 128. Preferably, there are at least three internally formed passages 132 extending between the opposite ends 128 of each of the radiator plates 126. However, in various other embodiments of the present invention, there may be more or less than three internally formed passages 132 within each or some of the radiator plates 126 and considered to be within the scope of the present invention. As seen in FIG. 5, the internally formed passages 132 expose in the cut-out portion 130. Referring again to FIG. 2, the opposite ends 128 of each of the radiator plates 126 are connected between the distributor and the collector headers 112, 114 in such a manner that the cut-out portions 130 at both the ends are fitted to the distributor/collector headersll2, 114. The cut-out portions 130 of each of the radiator plates 126 are fitted in such a manner that the exposed passages 132 within the cut-out portions 130 are aligned with the corresponding opening of the distributor and the collector headers 112, 114. respectively. The dimensions of the cut-out portion 130 of each of the radiator

plates 126 is chosen in such manner that it easily gets fitted to the curvature of the distributor/collector headers 112, 114.
Due to the above arrangement, the transformer oil which passes through the
distributor header 112 is received within the passages 132 of each of the radiator plates 126 through the corresponding opening of the distributor/collector headers 112, 114. The transformer oil that is received within the collector header 114 is then introduced within the transformer housing 104 and subsequently into the winding by known means. Thus, proper alignment of the openings 122 within the distributor/collector headers 112. 114 and the passages 132 within the radiator plates 126 becomes very important for effective passage and cooling which will be described below in the following description.
As seen in FIGS. 1-2, an axial flow fan 134 may be positionable proximal to the
plurality of radiator plates 124 to generate air flow that passes along a length of each of the radiator plates 126. Preferably, the axial flow fan 134 is positioned below the plurality of radiator plates 124 and linearly oriented along a longitudinal axis of the radiator unit 100 so as to allow each of the radiator plates 126 to sufficiently receive the generated airflow by the axial flow fan 134. The axial flow fan 134 is firmly attached to the collector header 114 through a bracket member 136. FIG. 6 shows a bottom view of the axial flow fan 134 positioned below the plurality of radiator plates 124, The bracket member 136 is firmly connected to the collector header 114 to securely attach the axial flow fan 134 with the collector header 114, In another embodiment of the present invention, the axial flow fan 134 may also be firmly attached with the transformer housing 104 and considered to be within the scope of the present invention. It is to be understood that the diameter of the circle circumscribed by the axial flow fan 134 is equal to the diameter of the plurality of radiator plates 124. This is to ensure maximum utilization of the airflow generated by the axial flow fan 134. Due to position of the axial flow fan 134 below the plurality of radiator plates 124, it will be understood that the direction of the transformer oil flow

and the air flow are opposite to each and this allows maximum cooling effect of the transformer oil running through the internal passages 132. However, according to another embodiment of the present invention, the axial flow fan 134 may also be positioned on top of the plurality of radiators and firmly coupled to the distributor header 112 of the radiator unit 100. In this arrangement, the direction of the transformer oil flow and the air flow will be in the same direction.
FIG. 7 shows simulation of the air flow that is generated by the axial flow fan 134
as noted above. As seen, the flow profile followed by the airflow, from the point it is being generated, varies as the airflow moves upwardly and away from the axial flow fan 134. Typically, the profile of the generated airflow adapts a curvilinear path as it moves away from the point of airflow generation by the axial flow fan 134. Keeping this consideration in view, each of the radiator plates 126 are designed to have a similar curvilinear profile (See FIGS. 2 and 4). Further, one of the opposite ends 128 of each of the radiator plates 126 are connected to the collector tube in such a manner that they are streamlined with the airflow generated immediate to the axial flow fan 134. Particularly, one of the opposite ends 128 of the radiator plates 126 are oriented with respect to the axial flow fan 134 in such a manner that outlet angle of the generated airflow is linearly aligned with each of the opposite ends 128 of the corresponding radiator plates 126. Furthermore, due to the fact that the shape of the radiator plate 126 is curvilinear towards the distributor header 112 the profile followed by the generated airflow allows the airflow to move along with the radiator plates 126 towards the other opposite ends 128. Preferably, this typical movement of the generated airflow takes place for a substantial length of the radiator plates 126 towards the other of the opposite ends 128 and therefore prevents sideways escape of the generated airflow. Thus, due to the profile of the radiator plate 126, the opposite end as well as a substantial portion of the radiator plate 126 is aligned with the generated airflow.

A skilled person in the art would appreciate that due to the above mentioned
constructional features of the plurality of radiator plates 124, the airflow gets an opportunity to smoothly enter between the radiator plates 126. Thus, the airflow covers maximum possible area of radiator plates 126 for better heat dissipation and that too with increased velocity. Higher velocity and better air flow distribution of air can be achieved by providing a smoother entry of the air through the streamlined radiator plates 126, The design also reduces the air wastages and avoids the back flow (back pressure) of the airflow, accordingly reduces the pressure drop. The streamlined profile of radiator plates 126 along the length provides the guide to the air and air remains in attached with the radiator surfaces for longer time as compared to prior art. As such, the residence time of the airflow within the plurality of radiator plates 124 increases. This allows the thermal performance of the transformer 102 to improve by improving better air flow distribution and enhanced heat dissipation. Thus, this also reduces the power consumption of the transformer 102 and also reduces noise of the axial flow fan 134. This will lead to higher heat transfer coefficients and higher cooling capacity thereby increased rating of transformer 102 for same size or lower size of radiators for same rating.
FIG. 8 shows another embodiment of the radiator unit 100' according to the
present invention. In this embodiment, construction of each of the radiator plates 126' is similar to the above mentioned radiator plates 126 apart from the cross-section of the radiator plates 126. As seen in FIG. 9, instead of having a curvilinear cross-section, the radiator plates 126' of this embodiment has a linear cross-section wherein width Wl of each of the radiator plates 126' nearer to the axial flow fan 134 is shorter than the width W2 of each of the radiator plates 126' distant from the axial flow fan 134. One of the opposite ends 128' of the radiator plates 126' having a shorter width Wl is attached to the collector header 114'. In this embodiment as well, the outlet angle of the airflow is approximately aligned with the one of the opposite ends 128'of each of the radiator plates 126' to allow the above noted benefits to be taken off by the

manufacturer. However, even though the residence time of airflow between the radiator plates 126' is less than that of the above embodiments, still it is sufficient to provide efficient and effective cooling of the transformer oil.
It will be apparent to those skilled in the art that various modifications and
variations can be made to the present invention without departing from the spirit and scope of the invention. Thus it is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.

We Claim:
1. A radiator unit couplable with an inlet and an outlet of a transformer housing for cooling of
transformer oil flowing through a transformer comprising:
a distributor header and a collector header coupled with the outlet and the inlet of the transformer housing, respectively, the distributor header and the collector header including a plurality of spaced apart openings formed along a circular portion of the distributor and collector headers;
a plurality of radiator plates vertically disposed in spaced apart relationship with each other and arranged in a circular configuration, each of the radiator plates extending between a pair of opposite ends and having atleast one internally formed passage that extends to open at the opposite ends, opposite ends of each of the radiator plates connected between the distributor and the collector headers and aligned with the corresponding opening of the distributor and the collector headers; and
an axial flow fan positionable proximal to the plurality of radiator plates to generate air flow that passes along the length of each of the radiator plates, one of the opposite ends and a sufficient portion adjacent to the opposite ends of each of the radiator plates streamlined with an outlet angle of the generated air flow.
2. The radiator unit according to claim 1, wherein each of the radiator plates have an oblong cross-sectional area, and wherein each of the radiator plates are bundled together and arranged in the circular configuration.
3. The radiator unit according to claim 1, wherein each of the radiator plates have a linear cross-sectional area, and wherein width of each of the radiator plates nearer to the axial flow fan is shorter than the width of each of the radiator plates distant from the axial flow fan.

4. The radiator unit according to claim 1, wherein the distributor and collector heads are formed to have a circular cross-section, and wherein the opposite ends of each of the radiator plates has a semi-circular cut-out portion to expose the at least one passage, the semi-circular cut-out portions fitted to the distributor and collector heads, respectively, to allow the at least one passage to be aligned with the corresponding openings of the distributor and collector heads.
5. The radiator unit according to claim 1, wherein three internally formed passages is formed within each of the radiator plates that extend to open at the opposite ends.
6. The radiator unit according to claim 1, wherein the axial flow fan is positioned below the plurality of radiator plates and linearly oriented thereof to allow each of the radiator plates to sufficiently receive the generated airflow.
7. The radiator unit according to claim 6, wherein the axial flow fan is firmly attached to collector header through a bracket member.
8. The radiator unit according to claim 1, wherein the distributor and collector heads are attached to the outlet and the inlet of the transformer housing through mechanical couplings.