A CONTAMINATION FREE INTERNAL OIL CIRCUIT BREAKER FOR OIL FILLED
TRANSFORMERS
Field of Invention
[001] The embodiments herein generally relate to an internal circuit breaker in an oil filled transformers. More specifically the embodiments described herein relate to an internal circuit breaker for complete self-protection of oil filled transformers with a mechanism to trap the carbon and metallic particles that are generated, which are contaminating the oil in the transformer due to overload and/or fault conditions. Particularly relates to a contamination free internal oil circuit breaker, duly trapping the carbon and metallic particles in a separate chamber of suitable insulation material, integrated with mesh and filter, and allowing to freely mix with the oil in a main tank.
Background of the Invention
[002] Typically, Oil filled distribution transformers are protected by an internally built circuit breaker at LT side against overload and/or short circuit conditions. A conventional internally built circuit breaker is connected in series at the LT side of the transformer used for overload protection duly considering the temperature of the oil, overload conditions and/or short circuit conditions. It is housed on the core coil assembly filled with oil. The circuit breaker breaks the contact and isolates the LT supply automatically in the event of overload that is determined by the breaker duly considering the combination of the preset temperature and load current, and/or short circuit conditions.
[003] Mineral oil used in the distribution transformer has good dielectric strength and thermal conductive properties. Its insulation level is, however, dependent upon the level of impurities. The existing breaker housed in the transformer tank isolates the LT circuit by separating the moving contacts and the fixed contacts utilizing the existing oil in the entire transformer for arc quenching.
[004] On separation of the moving contacts from the fixed contacts with oil assisted arc interruption, a high temperature greater than 658°K is developed. A temperature more than 500°K decomposes the oil into carbon and metallic particles.

[005] The regular operation of the breaker contaminates the main tank oil with the carbon and metallic particles which affects the insulation strength of the transformer. This phenomenon affects the performance and life of the transformer. More number of operations of the breaker increases the contamination of oil proportionately thus reducing the life of the transformer.
[006] Therefore, there is a need in the art to develop an internal circuit breaker forming a part of the complete self-protection for oil filled transformers avoiding contamination of oil to overcome the problem associated with the prior arts. Further, there is a need for an internal circuit breaker to prohibit contamination of oil in the main tank due to arcing occurred by breaking of contacts in the event of overload and/or fault conditions.
Objects of the Invention
[007] Some of the objects of the present disclosure are described herein below:
[008] A main object of the present invention is to provide an internal circuit breaker for complete self-protection of oil filled transformers, avoiding contamination of an existing oil in an entire transformer during overload and/or fault conditions.
[009] Another object of the present invention is to provide an internal circuit breaker with a mechanism to trap carbon and metal particles, that are generated due to the oil assisted arc interruption
[0010] Still another object of the present invention is to provide an internal circuit breaker to trap the contamination in the chamber during arc quenching and thereby, allowing the contamination free oil in the chamber to freely mix with the existing main tank oil of the transformer.
[0011] Yet another object of the present invention is to provide a chamber, which forms as a distinct barrier between the circuit breaker moving and fixed contacts and the main tank oil.
[0012] Another object of the present invention is to provide a chamber, which is composed of mesh integrated with filter.

[0013] Another object of the present invention is to provide a chamber in which flow of contamination free oil from the chamber (202) to the main tank in and out freely, is to maintain good insulation strength and breakdown voltage of the oil that is available in the chamber (202), for effective and efficient interruption of the breaker with oil assisted arc quenching.
[0014] Another object of the present invention is to provide a chamber in which the free flow of contamination free oil from the chamber (202) to the main tank in and out is to maintain near to, or equal temperature gradient of the oil available in the separate chamber and oil in the main tank.
[0015] Another object of the present invention is to provide a chamber (202) in which the free flow of contamination free oil from the chamber to the main tank in and out is to relieve the pressure in the separate chamber that may be formed due to abnormal conditions.
[0016] The other objects and advantages of the present invention will be apparent from the following description when read in conjunction with the accompanying drawings which are incorporated for illustration of preferred embodiments of the present invention and are not intended to limit the scope thereof.
Summary of the Invention
[0017] In view of the foregoing, an embodiment herein provides a contamination free internal oil circuit breaker for complete self-protection of oil filled transformers. According to an embodiment, the contamination free oil circuit breaker comprising a tripping mechanism, a chamber integrated with mesh and filter, an oil sealed linear bearing or bush with unique diaphragm seal at least a fixed contact, at least a moving contact, a pressure release valve, and a thermal overload bimetallic-sensors and transformer fault magnetic sensors.
[0018] According to an embodiment, the contamination free internal oil circuit breaker comprising of at least a fixed contact and at least a moving contact placed in the chamber, the thermal overload bimetallic-sensors and the transformer fault magnetic sensors are mounted on an outer side of said chamber, and the oil sealed linear bearing or bush with unique diaphragm seal is associated with said at least moving contact. A tripping mechanism of the circuit breaker is mounted outside the chamber, which initiates the tripping of the breaker during overload

and/or fault conditions. The circuit breaker contacts are separated and quenched with the available oil in said chamber. A high temperature of 658K or more is developed which decomposes the available oil in said chamber into carbon and metallic particles. The mesh integrated with filter traps the contamination within the chamber and allows the contamination free oil in the chamber to freely mix with the oil of a main tank of the transformer. The chamber is composed of mesh integrated with filter.
[0019] These and other aspects of the embodiments herein will be better appreciated and understood when considered in conjunction with the following description and the accompanying drawings. It should be understood, however, that the following descriptions, while indicating preferred embodiments and numerous specific details thereof, are given by way of illustration and not of limitation. Many changes and modifications may be made within the scope of the embodiments herein without departing from the spirit thereof, and the embodiments herein include all such modifications.
Brief Description of the Drawings
[0020] The detailed description is set forth with reference to the accompanying figures. In the figures, the use of the same reference numbers in different figures indicates similar or identical items.
[0021] Figure 1 illustrates a perspective view of an internal circuit breaker for complete self-Protection of oil filled transformers with a unique mechanism to trap contamination during overload and/or fault conditions, according to an embodiment therein; and
[0022] Figure 2 illustrates a detailed side view and rear view of an internal oil circuit breaker for complete self-Protection of oil filled transformers, according to an embodiment therein.
Detailed Description of the Preferred Embodiments
[0023] The embodiments herein and the various features and advantageous details thereof are explained more fully with reference to the non-limiting embodiments and detailed in the following description. Descriptions of well-known components and processing techniques are omitted so as, to not unnecessarily obscure the embodiments herein. The examples used herein are intended merely to facilitate an understanding of ways in which the embodiments herein may

be practiced and to further enable those of skill in the art to practice the embodiments herein. Accordingly, the examples should not be construed as limiting the scope of the embodiments herein.
[0024] As mentioned above, there remains a need for a contamination free internal oil circuit breaker for the oil filled transformers. The embodiments herein achieve this by providing a circuit breaker with a tripping mechanism mounted outside the chamber that initiates tripping in the breaker during overload and/or fault conditions and thereby the circuit breaker contacts are separated and quenched with the available oil in said chamber and allows the contamination free oil in the chamber to freely mix with the oil of a main tank oil of the transformer. Referring now to drawings, and more particularly to FIGS. 1 and 2, where similar reference characters denote corresponding features consistently throughout the figures, there are shown preferred embodiments.
[0025] In accordance with an embodiment, an internal circuit breaker is mounted on a core coil assembly of the transformer. The transformer core coil assembly is immersed in oil and is provided with high voltage terminals and low voltage terminals.
[0026] Figure 1 illustrates a perspective view (100) of an internal circuit breaker for complete self-protection of oil filled transformers with a unique mechanism to trap carbon and metallic particles, that are generated during overload and/or fault conditions and let the contamination free oil into the main tank, according to an embodiment. The circuit breaker mounted on the transformer core coil assembly is placed below the oil level (101). The contacts of the circuit breaker can be operated by an operating rod (102) and a signal lamp (103) is triggered for the circuit breaker actions of tripping due to overload and/or short circuit conditions.
[0027] Figure 2 illustrates a detailed side view and rear view of an internal circuit breaker (200) for complete self-Protection of oil filled transformers, according to an embodiment. In an embodiment, a circuit breaker in an oil filled transformer includes a tripping mechanism (201), a chamber (202) integrated with mesh and filter (203), an oil sealed linear bearing or bush(204) with unique diaphragm seal (210), atleast a fixed contact (205), atleast a moving contact (206), a pressure release valve or vent (207), a bottom cover (208) and a thermal overload bi-metallic sensors and transformer fault magnetic sensors 209.

[0028] According to an embodiment, the circuit breaker includes the fixed contact (205) and the moving contact (206) placed in the chamber (202). In a preferred embodiment, the chamber of suitable insulation material (202) is made of mesh integrated with filter 203 which forms a unique barrier between the contacts (the moving contacts 206 and the fixed contacts 205) of the circuit breaker and with the oil in the transformer main tank. According to an embodiment, the tripping mechanism (201) can be linked to the moving contact (206) through the oil sealed linear bearing or bush (204) with unique diaphragm seal (210). Further, the thermal overload bi¬metallic sensor and transformer fault magnetic sensors (209) can be housed on an outer side of the chamber 202. In an embodiment, the thermal overload bi-metallic sensor (209) is temperature dependent and can sense accordingly as per the overload conditions.
[0029] In a preferred embodiment, the tripping mechanism (201) of the internal circuit breaker mounted outside the chamber (202) initiates tripping of the breaker in the chamber (202) without the influence of temperature of the oil in the breaker chamber in the event of any type of fault condition and/or overload condition duly considering preset oil temperature and load current in combination. After initiation of the tripping mechanism (201) of the breaker, the moving contacts (206) are separated from the fixed contacts (205) in the chamber (202) and an arc is quenched with the available oil in the chamber (202) during opening of the contacts. As a result, oil assisted arc interruption, a high temperature greater then 658k or more is developed and decomposes the oil in the chamber (202) into carbon and metallic particles. The unique barrier of mesh integrated with filter (203) traps the carbon and metallic particles within the chamber (202) and the contamination free oil in the chamber (202) will freely mix with the oil of a main tank of the transformer.
[0030] According to an embodiment, an internal circuit breaker in an oil filled transformer initiates tripping during conditions which, include overloading of the transformer considering the oil temperature and load current in combination and/or fault conditions.
[0031] According to an embodiment, the normal pressure developed during the opening of moving from fixed contacts of the internal breaker will be released through the mesh integrated with filer provided and any further increase in pressure developed during fault conditions opens the pressure release valve (207) to release a part of the gas to reduce the pressure.

[0032] In an example embodiment, a section of the chamber (202) filled with oil can be made of mesh integrated with filter (203) to trap the contamination during overload and/or fault condition. In another embodiment, the chamber (202) can be made of mesh integrated with filter with suitable material and gauge (203) traps the contamination which occurred during arc quenching in the course of overload and/or fault conditions.
[0033] In an example embodiment, the chamber (201) can be made of insulation material can include wood but not limited to Fiber Reinforced Plastics such as the Sheet Molding Compound(SMC), Dough Molding Compound(DMC), fiberglass, ceramic, melamine, mica nylon or a metallic enclosure reinforced with any of the suitable insulation material at required areas to which suffice the requirements to possess insulation properties. According to an example embodiment, the mesh integrated with filter with suitable material and gauge (203), the mesh can include steel but not limited to other materials of greater strength and the filter can include PE (Polyester/Polyethylene), PP (Polypropylene), Nylon, PPS (Polyphenylene sulfide), P84 (Polyimide) ,PPFE (Polypropylene needled Felt Filter), PEFE ( Polyethene/Polyester needled Felt Filter), PTFE(Polytetrafluoroethylene), Nomex/Aramid (Aromatic polyamides), Glass fiber, but not limited to other materials suitable for filtering.
[0034] It is to be understood that the above description is intended to be illustrative, and not restrictive. Many other embodiments will be apparent to those of skill in the art upon reading and understanding the above description. Although the present invention has been described with reference to specific exemplary embodiments, it will be recognized that the invention is not limited to the embodiments described, but can be practiced with modification and alteration within the spirit and scope of the appended claims. Accordingly, the specification and drawings are to be regarded in an illustrative sense rather than a restrictive sense. The scope of the invention should, therefore, be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled.

We Claim:
1. A contamination free internal oil circuit breaker comprising:
atleast one fixed contact (205) and atleast one moving contact (206) placed in a chamber (202); a thermal overload bi-metallic sensor and a transformer fault magnetic sensor(209) mounted on an outside the said chamber (202); an oil sealed linear bearing or bush (204) with unique diaphragm seal (210) associated with said fixed contact (205); a tripping mechanism (201) mounted on the outside of said chamber (202);wherein during overload and/or fault conditions said tripping mechanism (201) initiates tripping and the moving contacts (206) are separated from the fixed contacts (205); wherein during separation of contacts, a high temperature is developed due to arcing which contaminates the oil due to generation of carbon and metallic particles in said chamber (202); and wherein said chamber (202) is provided with a mesh integrated with a filter (203) for trapping the contamination of the oil in said chamber (202).
2. The circuit breaker as claimed in claim 1, wherein said chamber (202) is made of insulating material.
3. The circuit breaker as claimed in claim 1, wherein said tripping mechanism (201) of the circuit breaker initiates tripping during overload duly considering preset oil temperature and load current in combination, and/or fault conditions.
4. The circuit breaker as claimed in claim 1, wherein said circuit breaker contacts are separated and quenched with the available oil in said chamber (202) after initiation of tripping mechanism 201.
5. The circuit breaker as claimed in claim 1, wherein said mesh integrated with filter (203) traps the contamination of the oil in the chamber (202) and the contamination free oil in the chamber (202) let freely to mix with the oil in a main tank of the transformer.
6. The circuit breaker as claimed in claim 1, wherein said bimetallic sensors and fault detecting magnetic sensors (209) which represent or depict the oil temperature of the main tank and not have any influence of temperature of the oil in the chamber (202) provided to give an accurate tripping of the internal breaker, during overload duly considering preset oil temperature of the main tank and load current of the transformer in combination, and/or fault conditions.