FORM 2
The Patents Act 1970
(39 of 1970)
&
The Patent Rules 2003
COMPLETE SPECIFICATION
(See Section 10 and rule 13) TITLE OF THE INVENTION;
AN ARC EXTINGUISHING POLYMER MATERIAL FOR
SWITCHING DEVICE
APPLICANT:
LAR$EN & TOUBRO LIMITED
L&T House, Ballard Estate, P.O. Box No. 278,
Mumbai, 400 001, Maharashtra . INDIA.
PREAMBLE OF THE DESCRIPTION:
THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES THE INVENTION
AND THE MANNER IN WHICH IT IS TO BE PERFORMED

A) TECHNICAL FIELD
[0001] The present invention generally relates to switching devices such as Moulded
Circuit Breaker(MCB), change over switches, switch gear, circuit breakers etc., and particularly to arc extinguishing mechanisms. The present invention more particularly relates to arc quenching devices in circuit breakers. The present invention more particularly relates to compositions or coatings provided on the walls of the arc extinguishing chamber or the insulators in the arc extinguishing devices.
B) BACKGROUND OF THE INVENTION
[0002] In electrical switches, the flow of electrical current is maintained by providing
a contact between the moving contacts and the stationary contacts. The moving contacts are mounted on a moving bridge. The moving bridge is moved away from the stationary contact, when the switch is turned off and the flow of current is stopped by isolating the moving and stationary contacts. However, the transient arcs, caused due to the inability of the contact in dropping the value of the current to zero instantaneously, can affect the components of the switch units adversely.
[0003] The electrical switches further comprise an arc quenching system to cut off the
arcs generated between the moving and stationary contacts of a system during the switching off condition. There are several systems used in the switching devices to quench the arc. The low-voltage circuit breakers use air as a medium and de -ion plate to quench the arc. High-voltage circuit breakers use metal plates or non-metallic arc chutes which divide and cool the
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arc. The high voltage circuit breakers often use a blast of high pressure air, a special dielectric gas, or immersion in mineral oil to quench the arc when the high voltage circuit is broken.
[0004] Most of the arc extinguishing material used in various switching devices
comprises polymeric compounds, which are nitrogen based. For an instance, the compounds like melamine, guanine, urethane and allantoin coating upon the insulated parts, release gases like N2, H2 and NH3 as the byproduct gases. Out of which, the percentage of N2 is very high. Similarly polyamide and polyamide polymer blend, upon thermal decomposition releases gases such as C02, CO (Major), N20, NH3, organic compounds. In yet another type, the insulators in the arc extinguishing are coated with compositions such as urea composition, which releases CO, N20 and C02 as the byproduct gases. C02 is the major gas released from such composition. The gases especially N2 and C02 have low thermal conductivity and dielectric strength. The improvement in the performance of the switching device due to the above material is very low or often observed to be negligible at overload currents.
[0005] In any switching device, there is a need of insulation for the housing material,
walls supporting the stack of de-ion plates, adjacent walls of the arc runner etc. In the design
of high voltage current limiting fuses, circuit interrupters or the like, it would be desirable to
provide arc-quenching compositions or gas-evolving materials that rapidly evolve gases under
the action of an electric arc to quench the arc and that have minimal tracking properties, and
that also have high thermal properties, high electrical insulation properties, and self-sustaining
structural properties. It would also be desirable to provide a relatively inexpensive to
manufacture and easy to install arc-quenching composition while maintaining the desirable
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arc-quenching properties, thermal properties, insulating properties and structural properties and especially the non-tracking properties. It would be further desirable to provide an arc-quenching material with improved arc and track resistance.
[0006] Hence there is a need to provide an effective arc quenching mechanism to
reduce the overall gases especially N2 and CO2 upon thermal decomposition. Further, there exists a need for a composition for coating the various insulation products, which upon thermal decomposition releases gases with superior thermal conductivity and dielectric strength. Improvement in the de-ionization process and high dielectric strength improves the basic insulation level (BIL) of the switching device thereby avoiding the further restriking of the arc.
C) OBJECT OF THE INVENTION
[0007] The primary object of the present invention is to develop an arc quenching
system with suitable polymeric material with given composition to provide improved performance of a protective switching device by reducing the arc parameters such as arc current, time and energy and to quench the arc generated between the contacts in the switching device.
[0008] Another object of the present invention is to develop an arc quenching system
provided with suitable polymeric coating on the insulator, on the walls of the housing current

carrying parts, walls supporting the stack of the de-ionizing plates, adjacent walls of the arc runner, to improve the performance and life of the components in the switching devices.
[0009] Yet another object of the present invention is to develop an arc quenching
system provided with suitable polymeric composition to release gases of high thermal conductivity and dielectric strength to improve the BIL of the switching device.
[0010] Yet another object of the present invention is to develop an arc quenching
system with suitable polymeric composition for switching devices to reduce the electrical conductivity of the arc thereby limiting the fault current.
[0011] Yet another object of the present invention is to develop an arc quenching
system with suitable polymeric Composition for switching devices to improve the dielectric strength of the medium to overcome the transient recovery voltage thereby avoiding any re-striking of the arc.
[0012] Yet another object of the present invention is to develop an arc quenching
system with suitable polymeric composition for switching devices to avoid the release any carbonaceous material that leads to the tracking of a conductive material upon the insulator thereby avoiding a flashover between the poles.

[0013] These and other objects and advantages of the present invention will become
readily apparent from the following detailed description taken in conjunction with the accompanying drawings.
D) SUMMARY OF THE INVENTION
[0014] The above mentioned shortcomings, disadvantages and problems are addressed
herein and which will be understood by reading and studying the following specification.
[0015] The various embodiments of the present invention provide an arc-quenching
system in an electrical switching device with an arc quenching polymeric composition. The polymeric composition includes a polymeric compound of Polytetraflouroethylene (PTFE) with suitable binder, which is used in any switching device as insulation for housing material, walls supporting the stack of deioflizsing plates, adjacent walls of the arc runner etc. It is also easy to apply an arc-quenching coating composition, comprising an arc-quenching or gas-evolving material component and a relatively non-tracking and non-conductive film-forming polymer component on the insulators. The arc-quenching coating composition according to the invention provides an effective electric arc extinction property by the rapid evolution of non-conductive quenching gases. The arc-quenching coating composition exhibits a high track resistance to the surface breakdown phenomena caused by the electric arc during the fault current conditions.
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[0016] According to one embodiment of the present invention, an arc extinguishing
device in the switching devices has insulators coated with polymeric compound of polytetraflouroethylene (PTFE) wjth suitable binder material. The binder material is a solid binder. The solid binder includes colloidal particles of PTFE. The liquid binder material is also used instead of solid binder, the liquid binder is an aqueous surfactant solution selected from a group including Fluorocafbon anionic surfactant, hydrocarbon anionic surfactant, Methanol and water, water along with Flourocarbon, anionic and hydrocarbon surfactant.
[0017] The polymeric compound of polytetraflouroethylene (PTFE) with suitable
binder material are coated on the walls of housing storing the current carrying parts of the switching device, the walls of the housing supporting the stack of deionization plates used in the arc extinguishing chamber, adjacent walls of the arc runner, etc.
[0018] The novel polymeric compound revealed, is CF based. Under thermal
decomposition, it releases gases such as H2 F, CF2 and CO. Major gases released are H2, CF2,
whose thermal conductivity is alrriost 10 times higher as compared to N2 and CO2. Similarly
the di-electric strength of CF compound is 12.6 KV/mm as against 2.85 KV/mm of CO2. Due
to increased di-electric strength and thermal conductivity of the inert gas released by
polymeric compound of PTFE, the overall performance of the switching device using the
polymeric material as an arc extinguishing insulator is improved. Typically with a protective
switching device such as Molded Case Breaker, the polymeric compound of PTFE with
binder shows better result in terms of reduction in fault current and arc energy at 6 KA, 240V,
50Hz. As compared to various types of arc extinguishing insulator, by using the insulator
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coated with PTFE, the arc current is reduced by 32% as against 20% and the arc energy is reduced by 76.5% as against 25 - 30%. The novel polymeric compound of PTFE coated on an insulator releases gases with superior thermal conductivity and di-electric strength upon thermal decomposition.
E) BRIEF DESCRIPTION OF THE DRAWINGS
[0019] The other objects, features and advantages will occur to those skilled in the art
from the following description of the preferred embodiment and the accompanying drawings in which:
[0020] FIG. 1 shows a table indicating the fault current, the reduction of the fault
current in percentage, arc energy and reduction in arc energy in percentage due to the current limiting technology provided by the individual gas releasing insulators coated with ammonia based compositions and used in an arc extinguishing device provided in a switching device.
[0021] FIG. 2 illustrates a chart indicating the reduction of the fault current due to the
current limiting technology provided by the individual gas releasing insulators coated with ammonia based compositions and used in an arc extinguishing device provided in a switching device.
[0022] FIG. 3 illustrates a chart indicating the reduction of the arc energy due to the
current limiting technology provided by the individual gas releasing insulators coated with

ammonia based compositions and used in an arc extinguishing device provided in a switching device.
[0023] FIG. 4 illustrates a chart indicating the reduction of the fault current due to the
current limiting technology provided by the individual gas releasing insulators coated with polymeric compound of the present invention and used in an arc extinguishing device provided in a switching device.
[0024] FIG. 5 illustrates a chart indicating the effect on the arc time due to the current
limiting technology provided by the individual gas releasing insulators coated with polymeric compound based compositions and used in an arc extinguishing device provided in a switching device.
[0025] FIG. 6 illustrates a Chart indicating the reduction in the arc energy due to the
current limiting technology provided by the individual gas releasing insulators coated with polymeric compound based compositions and used in an arc extinguishing device provided in a switching device.
[0026] Although the specific features of the present invention are shown in some
drawings and not in others. This is done for convenience only as each feature may be combined with any or all of the other features in accordance with the present invention.
F) DETAILED DESCRIPTION OF THE INVENTION
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[0027] In the following detailed description, a reference is made to the accompanying
drawings that form a part hereof, and in which the specific embodiments that may be practiced is shown by way of illustration. These embodiments are described in sufficient detail to enable those skilled in the art to practice the embodiments and it is to be understood that the logical, mechanical and other changes may be made without departing from the scope of the embodiments. The following detailed description is therefore not to be taken in a limiting sense.
[0028] The various embodiments of the present invention provide a polymeric
compound of PTFE for insulators in an arc quenching system in an electrical switching device. The PTFE composition improves the performance of a switching device by reducing the arc parameters such as arc current, arc time and arc energy. The improvement in performance is due to the release of inert gases by the thermal decomposition of the polymeric compound. The gases released have high thermal conductivity and dielectric strength. The high Thermal conductivity of the gases leads to the improvement in the de-ionization process and the high di-electric strength of the gases improves the Basic Insulation Level (BIL) of the switching device thereby avoiding the further re-striking of the arc. The BIL is an indicator of the dielectric strength.
[0029] The various embodiments of the present invention provide an arc-quenching
system in an electrical switching device with an arc quenching polymeric composition. The polymeric composition includes a polymeric compound of Polytetraflouroethylene (PTFE)
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with suitable binder, which is used in any switching device as insulation for housing material, walls supporting the stack of deionising plates, adjacent walls of the arc runner etc. It is also easy to apply an arc-quenching Coating composition, comprising an arc-quenching or gas-evolving material component and a relatively non-tracking and non-conductive film-forming polymer component on the insulators. The arc-quenching coating composition including a polymeric compound of Polytetraflouroethylene (PTFE) with suitable binder provides an effective electric arc extinction property by the rapid evolution of non-conductive quenching gases and the arc-quenching coating composition exhibits high track resistance to surface breakdown caused by the electric arc during fault current conditions.
[0030] According to one embodiment of the present invention, an arc extinguishing
device in the switching devices has insulators coated with polymeric compound of polytetraflouroethylene (PTFE) with suitable binder material. The binder material is a solid binder. The solid binder includes colloidal particles of PTFE. The liquid binder material is also used instead of solid binder. The liquid binder is an aqueous surfactant solution selected from a group including Fluorocafbon anionic surfactant, hydrocarbon anionic surfactant, Methanol and water, water along wjth Flourocarbon, anionic and hydrocarbon surfactant.
[0031] The polymeric compound of polytetraflouroethylene (PTFE) with suitable
binder material are coated on the walls of housing storing the current carrying parts of the switching device, the walls of the housing supporting the stack of deionization plates used in the arc extinguishing chamber, adjacent walls of the arc runner, etc.
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[0032] The novel polymeric compound revealed, is CF based. Under thermal
decomposition, it releases gases such as H2, F, CF2 and CO. Major gases released are H2, CF2, whose thermal conductivity is almost 10 times higher as compared to N2 and C02. Similarly the di-electric strength of CF compound is 12.6 KV/mm as against 2.85 KV/mm of C02. Due to increased di-electric strength and thermal conductivity of the inert gas released by polymeric compound of PTFE, the overall performance of the switching device using the polymeric material as an arc extinguishing insulator is improved. Typically with a protective switching device such as Molded Case Breaker, the polymeric compound of PTFE with binder shows better result in terms of reduction in fault current and arc energy at 6 KA, 240 V, 50Hz. As compared to various types of arc extinguishing insulator, by using the insulator coated with PTFE, the arc current is reduced by 32% as against 20% and the arc energy is reduced by 76.5% as against 25 - 30%. The novel polymeric compound of PTFE coated on an insulator releases gases with superior thermal conductivity and di-electric strength upon thermal decomposition.
[0033] FIG. 1 shows a table indicating the fault current, the reduction of the fault
current in percentage, arc energy and reduction in arc energy in percentage due to the current limiting technology provided by the individual gas releasing insulators coated with ammonia based compositions and used in an ftrc extinguishing device provided in a switching device.
[0034] Most of the arc extinguishing material used in the various switching devices
comprises polymeric compounds, which are nitrogen based. For an instance, the compounds
like melamine, guanine, urethane and allantoin coating upon the insulated parts, releases N2,
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H2 and NH3 as the byproduct gases. Out of which the percentage of N2 is very high. Similarly polyamide and polyamide polymer blend, upon thermal decomposition releases gases such as C02, CO (Major), N20, NH3, organic compounds. Yet other type of arc extinguishing insulators such as urea composition, releases CO, N20, CO2 as the byproduct gases. Major gas released is of C02. These gases especially N2 and CO2 are of low thermal conductivity and dielectric strength. Especially, the release of CO2 forms carbonaceous soot material upon the insulation thereby creating a conductive track, which further leads to flashover between the live parts. The improvement in performance of the switching device due to the above material is very low or often observed to be negligible at overload currents.
[0035] Most of the ablative material that is used in the existing product is N2 based
compound such as Nylon 6/6 & Nylon 6 which are of polyamide compound. In some cases the adjacent insulated current carrying parts are of Melamine formaldehyde or phenol formaldehyde, which are of major H2 and NH3 / CO based respectively. As explained above, the gases released by all these material upon thermal decomposition has low thermal conductivity and di-electric strength.
[0036] The insulators are heated due to the exposure to the arc. The coating compositions
on the insulators release gases at very high transient pressure and velocity upon thermal decomposition. Most of the insulator releases H2 N2 NH3, N20 and CO as the byproduct gases. These gases being inflammable and inert in nature do not burn by themselves even at the arcing temperature. Out of the various insulator compositions listed above, few of them were selected for study of their behavior and characteristics under fault condition.
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[0037] A chemical composition of Urea and other compounds are mixed for preparation
of the following 5 samples. In the sample 1, urea (AQC3) and the urethane are mixed in the ratio of 1:1. The second sample is prepared by mixing the urea (AQC3) and acrylic in the ratio of 1:1. The third sample is prepared by mining the urea (AQC3), urea (AQC10) and urethane in the ratio of 1:1:2. The forth sample is prepared by mixing UREA (AQC3), UREA (AQC10) and URETHANE in the ratio of 1:4:2. The fifth sample is prepared by mixing UREA (AQC3), UREA (AQC10) and URETHANE in the ratio of 1:1:2.
[0038] The short circuit test conducted at a fault level of 10KA, 240V, 50Hz for the 5
samples with the above composition. The insulator forms the part of the side walls supporting the de-ion plate placed one above the other in the stack of a MCB. During the arcing process, the insulator placed in the vicinity of the arc releases gases which aided in reducing the fault current and the arc energy. The Table-1 shows the reduction of the fault current and the arc energy due to the current limiting technology provided by the individual gas releasing insulators. The reduction in arc current is in the range of 16 - 23 % and the reduction of arc energy is in the range of 25 - 32%.
[0039] FIG. 2 illustrates a chart indicating the reduction of the fault current due to the
current limiting technology provided by the individual gas releasing insulators coated with ammonia based compositions and used in an arc extinguishing device provided in a switching device. Every insulator is thought of an ablative material but its utility as an arc extinguishing material solely depends upon the composition of the material, which decides its thermal and
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electrical properties. A chemical composition of Urea and other compounds are mixed in different proportions to form five samples. A short circuit test is conducted at a fault level of 10KA, 240V, 50Hz for the 5 samples. The FIG 2 indicates the maximum fault current and the range of fault current due to the gases released by different ammonia and urea based samples. The test result for the reduction of fault current due to the current limiting technology provided by the individual gas releasing insulators are indicated in the chart in FIG.2.
[0040] FIG. 3 illustrates a chart indicating the reduction of the arc energy due to the
current limiting technology provided by the individual gas releasing insulators coated with ammonia based compositions and used in an arc extinguishing device provided in a switching device. A chemical composition of Urea and other compounds are mixed in different proportions to form five samples. A short circuit test is conducted at a fault level of 10KA, 240V, 50Hz for the samples. The FIG 3 indicates the maximum value for the arc energy and the range of arc energy due to the gases released by different ammonia and urea based samples. The test result for reduction of in arc energy due to the current limiting technology provided by the individual gas releasing insulators are indicated in the chart in FIG.3.
[0041] FIG. 4 illustrates a chart indicating the reduction of the fault current due to the
current limiting technology provided by the individual gas releasing insulators coated with polymeric compound of the present invention and used in an arc extinguishing device provided in a switching device. A special insulated material with a composition of polytetraflouroethylene (PTFE) and suitable binder is identified for releasing a better gas
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which limits the arc current and the arc energy by an amount greater than that by the 5 samples mentioned above.
The polytetraflouroethylene (PTFE) composition is drawn in the form of sheet with no pigment thus making it a natural Color. A test similar to the one conducted on the 5 samples is conducted for the material with polytetraflouroethylene (PTFE) composition along with Nylon 6 insulated material. Differential Scanning calorimetric (DSC) analysis is carried out by using Mettler (DSC30) thermbanalyser system. 9.599 mg of the sample is weighed and sealed in aluminum crucible under controlled Nitrogen atmosphere. Then the sample is heated from 35°C to 350°C at the rate of 10°C / min. After the melting of the PTFE composition, the difference in the mass is compared with an empty aluminum crucible. The heat absorbed by the released gas from the insulatoris is recorded for analysis purpose. The onset temperature of crucible is set at 325.8°C and the Peak elevated temperature is set at 331.26°C. The heat absorbed (8H) in the process is 20.34 J/gm.
[0042] A thermo gravimetric analysis (TGA) is also carried out by using Mettler (TG-
50) thermoanalyser system. 20.318 mg of the sample is weighed in an alumina crucible and heated at a temperature of 40° to 90O°C under controlled nitrogen atmosphere and then heated from 900°c to 990°C under oxygen atmosphere at the rate of 20°C/min. The results of TGA analysis are as given as follows. The initial decomposition temperature is 470°C and the Peak decomposition temperature is 608 J°C, while the percentage of decomposition is 99.45. The above analysis provides the transition point temperature at 608.7°C at which the material starts decomposing from melting stage(liquid phase) to gaseous state(gaseous phase). At the
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transition point temperature, 99.45% of the material gets decomposed to gaseous state with a heat extraction capacity of 20.34 J/gm.
[0043] The test conducted on Nylon 6 and a Polymeric compound of PTFE at a short
circuit fault level of 6KA, 240V, 50Hz for consecutively 5 numbers of "O" shots to simulate the breaking operation of the switching device. The arc generated during each breaking operation increased the temperature of the insulating material, thereby burning the insulated material along its inner surface. The heating of the PTFE material released inert gases such as Hydrogen, Fluorine, carbonyl fluoride (CF2), Carbon monoxide (CO) and low molecular weight fluorocarbons (FC). Out of these, H2, (F) n, CF2 and FC are inert gases having very high thermal conductivity, which helps in cooling the arc at a faster rate. Also the dielectric strength of FC is very high (12.6 KV/mm) as compared to H2 (1.75 KV/mm), C02 (2.85 KV/mm) and N2 (3.5KV/mm) gases. This effect limits the fault current and arc energy by a substantial amount. FIG. 4 illustrates the comparison graph between Nylon 6 and PTFE over an effect of current on the said insulated materials.
[0044] FIG. 5illustrates a chart indicating the effect on the arc time due to the current
limiting technology provided by the individual gas releasing insulators coated with polymeric compound based compositions and used in an arc extinguishing device provided in a switching device. The FIG. 5 indicates a comparison of an effect of arc time between Nylon 6 and PTFE based materials.
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[0045] FIG. 6 illustrates a chart indicating the reduction in the arc energy due to the
current limiting technology provided by the individual gas releasing insulators coated with polymeric compound based compositions and used in an arc extinguishing device provided in a switching device. The FIG. 6 illustrates the comparison of the effect of arc energy between Nylon 6 and PTFE based insulated materials.
[0046] The samples of insujlated materials indicated in the table shown in FIG. I, upon
getting exposed to the arc, release gases such as N2, NH3, H2 etc at very high transient pressure, which limited the fault current by 20% and reduced the arc energy by 25 - 30%. In these samples, the amount of N2 gas release is very high as compared to hydrogen and other gases. Nylon 6 when gets exposed to the arc at a very high temperature, releases inert gases such as N2, NH3, H2 etc, which did not aided much in limiting the fault current. In this material the percentage of N2 gas released is very high as compared to other gases, while PTFE coated insulator upon heating above its boiling point, released inert gases such as Hydrogen, Fluorine (HF), carbonyl fluoride (CF2), Carbon monoxide (CO) and low molecular weight fluorocarbons (FC). The released inert gases limit the fault current by 32% and drastically reduce the arc energy by 76.5%. As observed in the above test cases, the major portion of gas released is N2 in most of the other insulators. The N2 has a thermal conductivity of 0.0243w/m/k and dielectric strength of 3.45KV/mm.In the case of PTFE, the major gas released is H2 and (F) n which has a thermal conductivity of 0.1684w/m/k and (0.0279) n w/m/k respectively. Hence the cooling effect of this gas is better in comparison to others. This further leads to reduction in electrical conductivity, increase in arc voltage and reduction in
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arc energy. Also the CF4 gas released by PTFE has very high dielectric strength of 12.6 KV/mm. This avoids any further rehstriking of arc.
G) ADVANTAGES OF THE INVENTION
[0047] Thus the various embodiments of the present invention provide a PTFE based
polymeric composition to quench arc effectively in the switching devices. When exposed to the arc, the PTFE based polymeric composition releases inert gases at high transient pressure which does not burn by itself but also helps in cooling the arc faster due to enhanced thermal conductivity.
[0048] The polymeric composition includes a polymeric compound of
Polytetraflouroethylene (PTFE) with suitable binder, which is used in any switching device as insulation for housing material, Walls supporting the stack of deionizsing plates, adjacent walls of the arc runner etc. It is also easy to apply an arc-quenching coating composition, comprising an arc-quenching or gas-evolving material component and a relatively non-tracking and non-conductive filmrforming polymer component on the insulators. The arc-quenching coating composition according to the invention provides an effective electric arc extinction property by the rapid evolution of non-conductive quenching gases and the arc-quenching coating composition exhibits high track resistance to surface breakdown caused by the electric are during fault current conditions.
[0049] The gas released by the PTFE based polymeric composition reduces the
electrical conductivity of the arc thereby limiting the fault current, reducing the total energy of
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the arc and also the arc time by a significant amount. The insulator coated with PTFE based polymeric composition improves the di-electric strength of the medium to overcome the transient recovery voltage thereby preventing any re-striking of the arc. The insulator upon burning does not release any carbonaceous material which leads to the tracking of conductive material upon the insulator thereby avoiding any flashover between the poles. The PTFE based polymeric composition coated on insulator and other housing materials in the arc extinguishing device improves the de-ionization of plasma due to high electron affinity of the released gas. For the switching devices of the same rating, the PTFE based composition enhances its overall rating, improves the fault level and electrical life.
[0050] Although the invention is described with various specific embodiments, it will
be obvious for a person skilled in the art to practice the invention with modifications. However, all such modifications are deemed to be within the scope of the claims.
[0051] It is also to be understood that the following claims are intended to cover all of
the generic and specific features of the present invention described herein and all the statements of the scope of the invention which as a matter of language might be said to fall there between.


Date: September 16, 2009 Place: Bangalore.

Patent Attorney

CLAIMS
What is claimed is:
1. An arc extinguishing device in switching devices comprising:
Insulators coated with polymeric compound of polytetraflouroethylene (PTFE) with suitable binder material.
2. The device according to claim 1, wherein the binder material is a solid binder.
3. The device according to claim 2, wherein the solid binder includes colloidal particles of PTFE.
4. The device according to claim 1, wherein the binder material is a liquid binder.
5. The device according to claim 4, wherein the liquid binder is an aqueous surfactant solution selected from a group including Fluorocarbon anionic surfactant, hydrocarbon anionic surfactant, Methanol and water, water along with Flourocarbon, anionic and hydrocarbon surfactant.
6. The device according claim 1, further comprising walls of housing coated with polymeric compound of polytetraflouroethylene (PTFE) with suitable binder material.
7. The device according to claim 6, wherein the walls of housing stores the current carrying parts of the switching device.
8. The device according to claim 6, wherein the walls of the housingysupports the stacly of deionization plates used in the arc extinguishing chamber.
Date: September 16, 2009 RAKESH PRABHU
Place: Bangalore. Patent Attorney