Title of Invention	COMPOSITE FOR IMPROVING PERFOMANCE OF CIRCUIT BREAKER
Abstract	A composite for improving performance of circuit breaker during arcing, said composite comprising resin material; and fillers adapted to release water molecules increasing the arc resistance thereby quenching the arc thus removing and absorbing heat generated during arcing. The present invention also relates to a method for removing and absorbing the heat generated during arcing, said method comprising heating the composite comprising a resin material and fillers between 200ºC and 570ºC; decomposing the composition so as to not to support combustion and/or provide dilution of any combustible medium thereby suppressing arc.

Title of Invention

COMPOSITE FOR IMPROVING PERFOMANCE OF CIRCUIT BREAKER

Abstract

A composite for improving performance of circuit breaker during arcing, said composite comprising resin material; and fillers adapted to release water molecules increasing the arc resistance thereby quenching the arc thus removing and absorbing heat generated during arcing. The present invention also relates to a method for removing and absorbing the heat generated during arcing, said method comprising heating the composite comprising a resin material and fillers between 200ºC and 570ºC; decomposing the composition so as to not to support combustion and/or provide dilution of any combustible medium thereby suppressing arc.

Full Text	COMPLETE AFTER PROVISIONAL LEFT ON 4/9/2006 FORM 2 THE PATENTS ACT, 1970 (39 of 1970) & The Patents Rules, 2003 COMPLETE SPECIFICATION (See section 10; rule 13) 1. -Title of the invention. - COMPOSITE FOR IMPROVING PERFORMANCE OF CIRCUIT BREAKER 2. Applicant (a) NAME : LARSEN & TOUBRO LIMITED (b) NATIONALITY : Indian (c) ADDRESS : L7 T House, Ballard Estate, Mumbai 400 001, State of Maharashtra, India 3. PREAMBLE TO THE DESCRIPTION The following specification particularly describes the invention and the manner in which it is to be performed : >' .C35 FIELD OF INVENTION The present .invention relates to a composite for arcing chamber for improving the performance of circuit breaker. More,- particularly,- the invention relates to a composite which ameliorates' reduction of the let through energy produced during short circuit condition in a circuit breaker thereby suppressing the arc thus improving performance of circuit breaker. The 'present invention also relates to a method for removing and absorbing the heat generated during arcing. The composite finds its application in the arcing chambers of the circuit breakers and the like. BACKGROUND AND PRIOR ART Electric devices such as switches, contactors and circuit breakers day in and day out switches on and off electrical current at .' supplied voltage level depending on user requirements:. The circuit breaker is a switching device that, responds to fault conditions such as overload, and short circuit . by tripping circuit breaker. The other devices .such as . contactor, switches, fuses have to withstand the overload for short time depending on their requirements •'. Circuit breaker interrupts an electric current of excessive in magnitudes. When a current magnitude is enough to operate and 'trip .the circuit breaker, a pair of contacts referred' as' .fixed and moving contact conducting the current are separated by preloaded springs. 2- Molded case circuit breaker uses air to extinguish the arc struck between pair of contacts when clearing fault in downstream equipment. It is usual for an electric arc to form between the pair, of contacts when a circuit breaker opens, this causes rapid erosion of the contacts in addition heat is generated during breaking of current that is absorbed by' adjacent components thereby causing damage to these components. . In order to extinguish the arc e.f iectiveiy cooling, splitting or lengthen the arc is generally practiced. The longer arc has a larger cooling surface, thus cooling increases and deionization of the gap between the contacts improves. The increased length "of the arc also increases its resistance and therefore decreases the current flow and the amount of 'heat that is created. In circuit breakers, the short circuit interruption time required is approximately one or two half cycles of an AC sine wave at maximum. When the. contacts open, the resulting arc continues to burn until the .current level passes through zero. The arc may re-ignite because of the insufficient width of the contact gap. The current that flows until the arc is extinguished produces. a heating effect, proportional to the I2t value (let-through-energy), of the' fault current. These devices are designed to . reduce the amount of let-^through-current otherwise' resulting let-through-energy that can damage protected components'. They have the ability to interrupt short circuit current within the first . half cycle of the fault. Limiting let-through-energy will protect against the harmful effects of. over-current -Excessive Heat, Mechanical Damage 3 It is ^therefore necessary to develop material that will further reduce let through energy during short circuit In addition, this will reduce heat generated and mechanical damage caused due. to heat. In addition to this developed material should. generate mainly carbon dioxide gas such that this gas will .generate pressure to blow out. arc and to extinguish--'are formed, due to effect of contact opening. The material should exhibits water molecules during short circuit-^such. that, it cools, the arc in addition this should form the endothermic reaction thereby reducing damage to contact system and contact erosion. US4006114 discloses a filled polypropylene composition having excellent flame retardance which is prepared by blending polypropylene resin with chlorinated paraffin hydrocarbon, chlorinated polyethylene, antimony oxide and alumina trihydrate. Thus :there;-is a .need . to provide for a composite to reduce the let through .energy produced during short circuit condition • in :a circuit breaker thereby suppress the arc thus improving , performance of circuit breaker. There is also a need 'For . a method for removing and absorbing the heat generated during arcing. The :.present. inventors have now found that improved suppression, of. .the.-heat produced during arcing can be achieved • by reducing the let through energy adopting a composite without hologenated material, which comprises a resin material and' performance improvement fillers, being selected so 'as to provide improved performance of the circuit breaker. 4 OBJECTS OF INVENTION Thus one. -object of the present invention is to provide composite', for. removing and absorbing heat generated during arcing thereby improving performance of circuit breaker during arcing. Another object of the present invention is to provide flame retardancy ;and smoke suppression during arcing phenomenon. Yet another object of the present invention is to provide a method" for' removing and absorbing the heat generated during arcing. SUMMARY OF INVENTION Thus .according. -to-, one aspect of the present invention there is • provided•- a composite for improving performance of circuit breaker during arcing, said composite comprising : resin material; and fillers adapted to release water molecules increasing the arc resistance thereby quenching the arc thus removing. and absorbing heat generated during arcing. According to. another aspect of the present invention there is 'provided a method for removing and absorbing the heat generated during arcing, said method comprising : heating the composite as described above comprising a resin material and. fillers' between 210°C and 400°C; 5 decomposing the composition so as to not to support combustion and/or provide dilution of. any combustible medium. thereby suppressing arc. DETAIL DESCRIPTION OF INVENTION In the present . invention the composite comprises polyurethane. (PU) (hereinafter referred to as XPU' ) resin material and: fillers ' for performance improvement. Halogenated material are not used. The fillers are selected * from alumina Tri hydrate (hereinafter referred to as ATH),, Alumina, Mineral filled / unfilled Thermoplastics (TP) ,'.' glass and Silicon Nitride or mixtures thereof. The addition' of individual- fillers or in mixtures are adapted to ' 'release . the ; -water molecules increasing the arc resistance ;thereby quenching the arc and act as a flame retardant and ' ' also prevent the flame propagation by cutting off the contact of flame with atmospheric oxygen by releasing the gases. The fillers comprises inorganic substances in the polymer chain which prevents formation of conductive path due to carbonization of the material on burning:.'/' increase _'in 'temperature. The said temperature ranges from 200°C to 570°C, preferably from 210°C to 400°C, more preferably from 210°C to 375 °C and most preferably from 210°C to 300°C. The loading of fillers in base PU is governed. by the viscosity of PU resin, wet ability of composite particles and its effective homogeneous composition.- , The , viscosity ranges from ford cup B8 60 seconds to 10 min preferably from 2 min to 10 min, more preferably from \90 to 120 seconds and most preferably from 6 60 to 70 seconds. This composite being thixotropic mass it is not possible to be in the limit of 100 seconds in ford cup B8. Viscosity in Ford 'B' Cup clearly indicates the time required to flow and filling of composite in mould to form a good component. With higher viscosity of composite formed mixing of fillers is a problem leading to molding issues, and in worst condition failure to mould, the component. Homogeneous composition formation itself indicates wet ability of fillers without which particle separation will take place leading to difficulties in molding the component. Mechanism of flame retardancy and smoke suppression includes stages of i) heating, ii) decomposition, iii) ignition, combustion and iv) propagation. The ATH, Alumina and polypropylene operates during heating and decomposition stages. The combination acts in first two stages of flame retardancy; this retards or prevents further stages. In addition the PP material on decomposition exhibits carbon dioxide that hinders 'oxygen. The fillers alumina and/or silicon nitride gives thermal and structural stability. The decomposition of ATH is strongly endothermic, thereby reducing heating of base polymer and in turn cooling of contact system. When ATH decomposes it. generates water molecules which extinguishes the flame, quenches the arc 7 and prevents further decomposition of insulating material. It also dilutes any combustible gases and hinders oxygen. The time this process starts, one more additive polypropylene (PP) in base polymer decomposes thereby generating carbon dioxide that further hinders oxygen and thereby partly' eliminating causes of high1 let thorough energy. The composite serves purpose insulator between fixed and moving contact thereby fulfilling electrical properties.. In closed position of circuit breakers, rated current flows through the main circuit of the pole being input via one of the terminals, flowing through the stationary contact and moving contact. During current breaking arc is formed between fixed and moving contact. The heat generated during short circuit is governed 'by peak current seen by the circuit breaker during' fault clearing. In order to limit the let through energy, effective way is to remove and/or absorb energy from arcing ' area. The composite of the present invention helps in removing and absorbing heat generated during arcing thereby improving performance of circuit breaker during arcing. In case of arc quencning mechanism generally used' in case of LV protection system polymer is supposed to. be protected for retaining insulating properties. This is possible only than the flame retardants partly deactivate due to heat generation in arcing zone, this phenomenon should be repeated after each interval through out the. life of protection device. Also, if temperature goes . ^beyond, the 8 degradation temperature of polymer some ' part of flame retardant should be made available in composite for deactivation so that the insulating material doesn't catch fire protecting the system. It should be done, in such a manner that the temperature of the insulating material should be at lower' operating range & the gases evolved during burning of material should facilitate during arc quenching. Also fillers should impart the desired insulating properties and structural stability even at elevated operating temperatures. In absence of this insulating material may deform which can cause malfunction of protection device. There is no point in using different types flame retardants and/or quantities which deactivates after the polymer chain ceases. 9 WE CLAIM 1. A composite for improving performance of circuit breaker during arcing, said composite, comprising : resin material; and fillers adapted' to release water molecules increasing the arc resistance thereby quenching the are thus removing and absorbing heat generated during arcing. 2. A composite as claimed in claim 1, wherein the resin material comprises polyurethane resins. 3. A composite as claimed in claims 1 and 2, wherein the polyurethane resin has viscosity ranging from 20 to 100 seconds, more preferably from 40 to 90 seconds and most preferably from. 60 to 70 seconds, in ford cup B8 4. A composite as claimed in claims 1 to 3, wherein the fillers are selected from alumina tri hydrate (ATH), alumina, mineral filled and/or unfilled thermoplastics (TP), glass and silicon nitride or mixtures thereof. 5. A composite as claimed in claims 1 to 4, . whiter-sin the fillers comprises inorganic substances in the polymer chain adapted to prevent formation of conductive path due to carbonization of the material on burning and/or increase in temperature. 6. A method for removing and absorbing the heat generated during arcing, said method comprising : 10 heating the composite comprising a resin material and fillers between 200°C and 570 °.C; decomposing the composition so as to not to support combustion and/or provide dilution of any combustible medium thereby suppressing arc. 7. A method as claimed in claim 6, wherein the heating temperature ranges preferably from 210°C to 400°C, more preferably from 210°C to 375 °C and most preferably from 210°C to 300°C. 8. A method as claimed in claims 6 and 7, wherein the decomposition of the composition is endothermic. Dated this 4th day of September 2006 11 ABSTRACT COMPOSITE FOR IMPROVING PERFORMANCE OF CIRCUIT BREAKER A composite .for improving performance of circuit breaker during arcing, said composite comprising resin material; and fillers adapted to release water molecules increasing the arc resistance thereby quenching the arc thus removing and absorbing heat generated during arcing the present invention also relates to a method for removing and absorbing the heat generated during arcing, said method comprising heating the composite comprising a resin material and fillers between 200°C and 570°C; decomposing the composition so as to not to support combustion and/or provide dilution of any combustible medium thereby suppressing arc. 4 SEP 2006

Full Text

COMPLETE AFTER PROVISIONAL LEFT ON 4/9/2006
FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
The Patents Rules, 2003
COMPLETE SPECIFICATION
(See section 10; rule 13)

1. -Title of the invention. -

COMPOSITE FOR IMPROVING PERFORMANCE OF CIRCUIT BREAKER

2. Applicant
(a) NAME : LARSEN & TOUBRO LIMITED
(b) NATIONALITY : Indian
(c) ADDRESS : L7 T House, Ballard Estate, Mumbai 400 001,
State of Maharashtra, India
3. PREAMBLE TO THE DESCRIPTION
The following specification particularly describes the invention and the manner in which it is to be performed :

*>'

.C35

FIELD OF INVENTION
The present .invention relates to a composite for arcing chamber for improving the performance of circuit breaker. More,- particularly,- the invention relates to a composite which ameliorates' reduction of the let through energy produced during short circuit condition in a circuit breaker thereby suppressing the arc thus improving performance of circuit breaker.
The 'present invention also relates to a method for removing and absorbing the heat generated during arcing.
The composite finds its application in the arcing chambers of the circuit breakers and the like.
BACKGROUND AND PRIOR ART
Electric devices such as switches, contactors and circuit breakers day in and day out switches on and off electrical current at .' supplied voltage level depending on user requirements:. The circuit breaker is a switching device that, responds to fault conditions such as overload, and short circuit . by tripping circuit breaker. The other devices .such as . contactor, switches, fuses have to withstand the overload for short time depending on their requirements •'.
Circuit breaker interrupts an electric current of excessive in magnitudes. When a current magnitude is enough to operate and 'trip .the circuit breaker, a pair of contacts referred' as' .fixed and moving contact conducting the current are separated by preloaded springs.
2-

Molded case circuit breaker uses air to extinguish the arc struck between pair of contacts when clearing fault in downstream equipment. It is usual for an electric arc to form between the pair, of contacts when a circuit breaker opens, this causes rapid erosion of the contacts in addition heat is generated during breaking of current that is absorbed by' adjacent components thereby causing damage to these components. . In order to extinguish the arc e.f iectiveiy cooling, splitting or lengthen the arc is generally practiced. The longer arc has a larger cooling surface, thus cooling increases and deionization of the gap between the contacts improves.
The increased length "of the arc also increases its resistance and therefore decreases the current flow and the amount of 'heat that is created. In circuit breakers, the short circuit interruption time required is approximately one or two half cycles of an AC sine wave at maximum. When the. contacts open, the resulting arc continues to burn until the .current level passes through zero. The arc may re-ignite because of the insufficient width of the contact gap. The current that flows until the arc is extinguished produces. a heating effect, proportional to the I2t value (let-through-energy), of the' fault current. These devices are designed to . reduce the amount of let-^through-current otherwise' resulting let-through-energy that can damage protected components'. They have the ability to interrupt short circuit current within the first . half cycle of the fault. Limiting let-through-energy will protect against the harmful effects of. over-current -Excessive Heat, Mechanical Damage
3

It is ^therefore necessary to develop material that will further reduce let through energy during short circuit In addition, this will reduce heat generated and mechanical damage caused due. to heat. In addition to this developed material should. generate mainly carbon dioxide gas such that this gas will .generate pressure to blow out. arc and to extinguish--'are formed, due to effect of contact opening. The material should exhibits water molecules during short circuit-^such. that, it cools, the arc in addition this should form the endothermic reaction thereby reducing damage to contact system and contact erosion.
US4006114 discloses a filled polypropylene composition having excellent flame retardance which is prepared by blending polypropylene resin with chlorinated paraffin hydrocarbon, chlorinated polyethylene, antimony oxide and alumina trihydrate.
Thus :there;-is a .need . to provide for a composite to reduce the let through .energy produced during short circuit condition • in :a circuit breaker thereby suppress the arc thus improving , performance of circuit breaker. There is also a need 'For . a method for removing and absorbing the heat generated during arcing.
The :.present. inventors have now found that improved suppression, of. .the.-heat produced during arcing can be achieved • by reducing the let through energy adopting a composite without hologenated material, which comprises a resin material and' performance improvement fillers, being selected so 'as to provide improved performance of the circuit breaker.
4

OBJECTS OF INVENTION
Thus one. -object of the present invention is to provide composite', for. removing and absorbing heat generated during arcing thereby improving performance of circuit breaker during arcing.
Another object of the present invention is to provide flame retardancy ;and smoke suppression during arcing phenomenon.
Yet another object of the present invention is to provide a method" for' removing and absorbing the heat generated during arcing.
SUMMARY OF INVENTION
Thus .according. -to-, one aspect of the present invention there is • provided•- a composite for improving performance of circuit breaker during arcing, said composite comprising : resin material; and
fillers adapted to release water molecules increasing the arc resistance thereby quenching the arc thus
removing. and absorbing heat generated during arcing.
According to. another* aspect of the present invention there is 'provided a method for removing and absorbing the heat generated during arcing, said method comprising :
heating the composite as described above comprising a resin material and. fillers' between 210°C and 400°C;
5

decomposing the composition so as to not to support combustion and/or provide dilution of. any combustible medium.
thereby suppressing arc.
DETAIL DESCRIPTION OF INVENTION
In the present . invention the composite comprises polyurethane. (PU) (hereinafter referred to as XPU' ) resin material and: fillers ' for performance improvement. Halogenated material are not used. The fillers are selected * from alumina Tri hydrate (hereinafter referred to as ATH),, Alumina, Mineral filled / unfilled Thermoplastics (TP) ,'.' glass and Silicon Nitride or mixtures thereof. The addition' of individual- fillers or in mixtures are adapted to ' 'release . the ; -water molecules increasing the arc resistance ;thereby quenching the arc and act as a flame retardant and ' ' also prevent the flame propagation by cutting off the contact of flame with atmospheric oxygen by releasing the gases. The fillers comprises inorganic substances in the polymer chain which prevents formation of conductive path due to carbonization of the material on burning:.'/' increase _'in 'temperature. The said temperature ranges from 200°C to 570°C, preferably from 210°C to 400°C, more preferably from 210°C to 375 °C and most preferably from 210°C to 300°C. The loading of fillers in base PU is governed. by the viscosity of PU resin, wet ability of composite particles and its effective homogeneous composition.- , The , viscosity ranges from ford cup B8 60 seconds to 10 min preferably from 2 min to 10 min, more preferably from \90 to 120 seconds and most preferably from
6

60 to 70 seconds. This composite being thixotropic mass it is not possible to be in the limit of 100 seconds in ford cup B8. Viscosity in Ford 'B' Cup clearly indicates the time required to flow and filling of composite in mould to form a good component. With higher viscosity of composite formed mixing of fillers is a problem leading to molding issues, and in worst condition failure to mould, the component. Homogeneous composition formation itself indicates wet ability of fillers without which particle separation will take place leading to difficulties in molding the component.
Mechanism of flame retardancy and smoke suppression includes stages of
i) heating,
ii) decomposition,
iii) ignition, combustion and
iv) propagation.
The ATH, Alumina and polypropylene operates during heating and decomposition stages. The combination acts in first two stages of flame retardancy; this retards or prevents further stages. In addition the PP material on decomposition exhibits carbon dioxide that hinders 'oxygen. The fillers alumina and/or silicon nitride gives thermal and structural stability.
The decomposition of ATH is strongly endothermic, thereby reducing heating of base polymer and in turn cooling of contact system. When ATH decomposes it. generates water molecules which extinguishes the flame, quenches the arc
7

and prevents further decomposition of insulating material. It also dilutes any combustible gases and hinders oxygen.
The time this process starts, one more additive polypropylene (PP) in base polymer decomposes thereby generating carbon dioxide that further hinders oxygen and thereby partly' eliminating causes of high1 let thorough energy.
The composite serves purpose insulator between fixed and moving contact thereby fulfilling electrical properties..
In closed position of circuit breakers, rated current flows through the main circuit of the pole being input via one of the terminals, flowing through the stationary contact and moving contact. During current breaking arc is formed between fixed and moving contact.
The heat generated during short circuit is governed 'by peak current seen by the circuit breaker during' fault clearing. In order to limit the let through energy, effective way is to remove and/or absorb energy from arcing ' area. The composite of the present invention helps in removing and absorbing heat generated during arcing thereby improving performance of circuit breaker during arcing.
In case of arc quencning mechanism generally used' in case of LV protection system polymer is supposed to. be protected for retaining insulating properties. This is possible only than the flame retardants partly deactivate due to heat generation in arcing zone, this phenomenon should be repeated after each interval through out the. life of protection device. Also, if temperature goes . ^beyond, the
8

degradation temperature of polymer some ' part of flame retardant should be made available in composite for deactivation so that the insulating material doesn't catch fire protecting the system. It should be done, in such a manner that the temperature of the insulating material should be at lower' operating range & the gases evolved during burning of material should facilitate during arc quenching. Also fillers should impart the desired insulating properties and structural stability even at elevated operating temperatures. In absence of this insulating material may deform which can cause malfunction of protection device. There is no point in using different types flame retardants and/or quantities which deactivates after the polymer chain ceases.
9

WE CLAIM
1. A composite for improving performance of circuit
breaker during arcing, said composite, comprising :
resin material; and
fillers adapted' to release water molecules increasing the arc resistance thereby quenching the are thus
removing and absorbing heat generated during arcing.
2. A composite as claimed in claim 1, wherein the resin material comprises polyurethane resins.
3. A composite as claimed in claims 1 and 2, wherein the polyurethane resin has viscosity ranging from 20 to 100 seconds, more preferably from 40 to 90 seconds and most preferably from. 60 to 70 seconds, in ford cup B8
4. A composite as claimed in claims 1 to 3, wherein the fillers are selected from alumina tri hydrate (ATH), alumina, mineral filled and/or unfilled thermoplastics (TP), glass and silicon nitride or mixtures thereof.
5. A composite as claimed in claims 1 to 4, . whiter-sin the fillers comprises inorganic substances in the polymer chain adapted to prevent formation of conductive path due to carbonization of the material on burning and/or increase in temperature.
6. A method for removing and absorbing the heat generated
during arcing, said method comprising :
10

heating the composite comprising a resin material and fillers between 200°C and 570 °.C;
decomposing the composition so as to not to support combustion and/or provide dilution of any combustible medium thereby suppressing arc.
7. A method as claimed in claim 6, wherein the heating temperature ranges preferably from 210°C to 400°C, more preferably from 210°C to 375 °C and most preferably from 210°C to 300°C.
8. A method as claimed in claims 6 and 7, wherein the decomposition of the composition is endothermic.
Dated this 4th day of September 2006

11

ABSTRACT
COMPOSITE FOR IMPROVING PERFORMANCE OF CIRCUIT BREAKER
A composite .for improving performance of circuit breaker during arcing, said composite comprising resin material; and fillers adapted to release water molecules increasing the arc resistance thereby quenching the arc thus removing and absorbing heat generated during arcing the present invention also relates to a method for removing and absorbing the heat generated during arcing, said method comprising heating the composite comprising a resin material and fillers between 200°C and 570°C; decomposing the composition so as to not to support combustion and/or provide dilution of any combustible medium thereby suppressing arc.
4 SEP 2006

Documents:

http://ipindiaonline.gov.in/patentsearch/GrantedSearch/viewdoc.aspx?id=956KLWfVkfKAw84SEOQXZQ==&loc=vsnutRQWHdTHa1EUofPtPQ==

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Patent Number

277256

Indian Patent Application Number

1081/MUM/2005

PG Journal Number

48/2016

Publication Date

18-Nov-2016

Grant Date

16-Nov-2016

Date of Filing

06-Sep-2005

Name of Patentee

LARSEN & TOUBRO LIMITED

Applicant Address

L & T HOUSE, BALLARD ESTATE, MUMBAI 400 001,

Inventors:

#	Inventor's Name	Inventor's Address
1	MHASKAR, PRAVIN PRAKASH	SWITCHGER DESIGN & DEVLOPMENT CENTER, LARSEN & TOUBRO LIMITED, ELECTRICAL SECTOR-(EBG), PAWAI WORKS (E) GATE NO.7 SAKI VIHAR ROAD MUMBAI 400 072
2	VAIRAGI, PRASHANT BHASKAR	SWITCHGER DESIGN & DEVLOPMENT CENTER, LARSEN & TOUBRO LIMITED, ELECTRICAL SECTOR-(EBG), PAWAI WORKS (E) GATE NO.7 SAKI VIHAR ROAD MUMBAI 400 072

PCT International Classification Number

C08L75/00

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1			NA