CN104680030A - Method for determining cross section of intelligent element of fire circuit breaker - Google Patents
Method for determining cross section of intelligent element of fire circuit breaker Download PDFInfo
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- CN104680030A CN104680030A CN201510115394.XA CN201510115394A CN104680030A CN 104680030 A CN104680030 A CN 104680030A CN 201510115394 A CN201510115394 A CN 201510115394A CN 104680030 A CN104680030 A CN 104680030A
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- intelligent element
- sectional area
- density
- circuit
- intelligent
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Abstract
The invention discloses a method for determining a cross section of an intelligent element of a fire circuit breaker. The method comprises the following steps of deducing a relation of the mass and a sectional area of the intelligent element according to a density formula; deducing a relation of specific heat and mass of a material used by the intelligent element, a rated current intensity of a circuit and a time parameter for disconnecting the circuit when the overcurrent occurs in the circuit according to the sectional area, heat absorption amount, temperature different and Joule-Lenz's law of a resistor and the intelligent element; calculating a sectional area expression of the intelligent element, establishing a sectional model of the intelligent element of the fire circuit breaker, and determining the sectional area of the intelligent element. According to the method, the condition that the sectional area of the intelligent element depends on the square of the rated current under the situation that the type of the material of the intelligent element is determined can be deduced, i.e. the sectional area of the intelligent element is determined by the square of the rated current, and the required sectional area is larger when the rated current is greater.
Description
Technical field
The present invention relates to a kind of defining method of fire isolating switch intelligent element cross section.
Background technology
About when 2015 on January 2, afternoon 13, warehouse, location one is surrounded nearly 25 hours on fire in Jie Yunanxun in romote antiquity street, its influencing factors on Daowai district, Heilungkiang, the warehouse that overdoes caves in, cause firefighters 5 people wrecked, 13 people are injured, separately to have in 1 building security personnel injured, 549 families resident more than 2000 and the overlooking trade company of part disaster-stricken, burnt area 11000 square meter, cave in area 3000 square meter.In current fire, set out 152 fire trucks, 642 fire fighters participate in rescue.The big fire that gold river, Genhe City, the Inner Mongol on the 31st January in 2015 plate industry workshop occurs, burn again nearly 51 hours, cause 6 people dead, 3 people are injured.Big fire occurs again for store, Yiwu, Huidong, Guangdong on the 5th February in 2015, dead 17 people, and 5 fire fighters are injured.Big fire occurs again and again, and as the big fire of warehouse, Harbin, its reason is that the circuit caused because of electric heater overload is on fire.If be equipped with so a kind of isolating switch in the circuit of storehouse, circuit can disconnect when circuit overload by its intelligent element, or also circuit can be disconnected when breaking out of fire, is beneficial to water spray rescue.If so, big fire just can not be burnt the so long time, also would not cause so large life and property loss.The sectional area of intelligent element is how many times, could accurate perception circuit overload.As can be seen here, the cross section of isolating switch intelligent element is modeled in the size design of intelligent element and has just become the key of problem to be solved.
Summary of the invention
The present invention is in order to solve the problem, propose a kind of defining method of fire isolating switch intelligent element cross section, when this method can solve the design of conducting transmission line fire isolating switch intelligent element, when known materials kind and rated power, the problem of the sectional area of intelligent element during circuit overload can not be determined rapidly.
To achieve these goals, the present invention adopts following technical scheme:
The defining method in fire isolating switch intelligent element cross section, comprises the following steps:
(1) quality and the sectional area relation of intelligent element is derived according to density formula;
(2) in conjunction with resistance and intelligent element sectional area, recept the caloric and the temperature difference and joule lenzs law, the relation between the time parameter deriving the disconnecting circuit allowed when overcurrent appears in the specific heat of intelligent element material therefor, quality, the rated current intensity of circuit and circuit;
(3) integrating step (1), (2), calculate the sectional area expression formula of intelligent element, build fire isolating switch intelligent element cross section model, determine the cross-sectional sizes of intelligent element.
The concrete grammar of described step (1) is: the equation (1) of being derived quality and intelligent element sectional area by density formula,
ρ
density=m/v=m/sL
M=sL ρ
density(1)
In formula, s is the sectional area of intelligent element, ρ
densityfor the density of intelligent element material therefor, L is the length of intelligent element, and v is the volume of intelligent element.
The concrete grammar of described step (2) is: the relational expression (2) listing resistance and intelligent element sectional area,
R=ρ
resistivityl/s (2)
List the relational expression (3) of caloric receptivity and the temperature difference (being exactly phase transition temperature) here,
Q＝cm△T (3)
List the relational expression (4) of joule lenzs law,
Q＝0.24I
2Rt (4)
By (3), (4) simultaneous, obtain relational expression (5),
cm△T＝0.24I
2Rt (5)
In formula, s is the sectional area of intelligent element, and I is the rated current intensity by circuit, the time of disconnecting circuit of t for allowing when overcurrent appears in circuit, ρ
resistivityfor the resistivity of intelligent element material therefor, c is the specific heat of intelligent element material therefor, ρ
densityfor the density of intelligent element material therefor, △ T is the starting temperature of transformation As of intelligent element material therefor and 1/2nd of phase transformation end temp Af sum.
In described step (3), concrete grammar is, quality and the sectional area relational expression of the intelligent element relational expression of resistance and intelligent element sectional area and step (1) obtained bring the relational expression derived in step (2) into, can obtain:
S
2=0.24I
2t ρ
resistivity/ c ρ
density△ T (8),
According to Area Model, the size of design intelligent element,
In formula, s is the sectional area of intelligent element, and I is the rated current intensity by circuit, the time of disconnecting circuit of t for allowing when overcurrent appears in circuit, ρ
resistivityfor the resistivity of intelligent element material therefor, c is the specific heat of intelligent element material therefor, ρ
densityfor the density of intelligent element material therefor, △ T is the starting temperature of transformation As of intelligent element material therefor and 1/2nd of phase transformation end temp Af sum.
Beneficial effect of the present invention is:
(1) easy the deriving of the present invention, when the material category of intelligent element is determined, the sectional area of intelligent element depend on rated current square, i.e. sectional area square to determine by rated current of intelligent element, that is the larger required sectional area of rated current is larger;
(2) length in intelligent element bar portion and rated current have nothing to do, and its length is only decided according to the actual requirements, and obtain shorter, cost is lower;
(3) according to Area Model of the present invention, intelligent element Design seriation can be made in conjunction with rated power.
Embodiment:
Below in conjunction with embodiment, the invention will be further described.
The defining method in circuit fire isolating switch intelligent element cross section, comprises the following steps:
The first step derives the equation (1) of quality and intelligent element sectional area by density formula,
∵ ρ
density(unit is=m/v=m/sL: kg/m
3=kg/m
3=kg/m
2m)
∴ m=sL ρ
density(1)
Second step lists the relational expression (2) of resistance and intelligent element sectional area,
R=ρ
resistivity(unit is L/s (2): Ω=Ω m × m/m
2)
3rd step lists the relational expression (3) of caloric receptivity and the temperature difference (being exactly phase transition temperature) here,
Q=cm △ T (3) (unit is: J=J/kg DEG C × kg × DEG C)
4th step lists the relational expression (4) of joule lenzs law,
Q=0.24I
2(unit is Rt (4): J=A
2× Ω × s)
5th step, by (3) (4) simultaneous, obtains (5),
(3) (4) simultaneous:
cm△T＝0.24I
2Rt (5)
(1) (2) formula is substituted into (5) formula by the 6th step, obtains (8):
CsL ρ
density△ T=0.24I
2t ρ
resistivityl/s (6), arranges:
Cs
2ρ
density△ T=0.24I
2t ρ
resistivity(7), arrange:
S
2=0.24I
2t ρ
resistivity/ c ρ
density△ T (8)
Physical quantity explanation in Area Model representated by letter
In formula, s is the sectional area of intelligent element, and I is the rated current intensity by circuit, the time of disconnecting circuit of t for allowing when overcurrent appears in circuit, ρ
resistivityfor the resistivity of intelligent element material therefor, c is the specific heat of intelligent element material therefor, ρ
densityfor the density of intelligent element material therefor, △ T is 1/2nd of the As+Af phase transition temperature of intelligent element material therefor.
The physical unit explanation that in Area Model, each physical quantity uses
In formula (8), the unit of s is a square metre (m
2), the unit of I is peace (A), and the unit of t is second (s), ρ
resistivityunit to be the unit of ohm meter (Ω m), c be joule/kilogram to open (J/kg DEG C), ρ
densityunit be kilograms per cubic meter (kg/m
3), the unit of △ T is DEG C.
Embodiment 1:
Known: resistivity mean value ρ
resistivity=0.8 × 10
-6Ω m, specific heat mean value c=545J/kg DEG C, density average ρ
density=6450kg/m
3, by martensite, (peak temperature equals 1/2nd of As+Af phase transition temperature to peak temperature △ T=80 DEG C that parent phase changes; These data all can check in from the table 1-5 of " marmem and analytical test Comprehensive Experiment " book).
Rated current I=5 is made to pacify (A), power-off time t=2 second (s),
Then s
2=0.24 × 5
2× 2 × 0.8 × 10
-6/ 545 × 6450 × 80=3.4136975 × 10
-14(m
2)
2
s＝3.4136975
1/2×10
-7(m
2)
s＝1.8476194×10
-7×10
6(mm
2)＝0.18476194(mm
2)
If the radius of silk is r, then have:
3.14r
2＝0.18476194
r
2＝0.0588413
R=0.2425724 (millimeter), when namely rated current is 5A, its radius r=0.2425724 of intelligent element (millimeter) is just passable.
The specific embodiment of the present invention is described although above-mentioned in conjunction with the embodiments; but not limiting the scope of the invention; one of ordinary skill in the art should be understood that; on the basis of technical scheme of the present invention, those skilled in the art do not need to pay various amendment or distortion that creative work can make still within protection scope of the present invention.
Claims (4)
1. the defining method in fire isolating switch intelligent element cross section, is characterized in that: comprise the following steps:
(1) quality and the sectional area relation of intelligent element is derived according to density formula;
(2) in conjunction with resistance and intelligent element sectional area, recept the caloric and the temperature difference and joule lenzs law, the relation between the time parameter deriving the disconnecting circuit allowed when overcurrent appears in the specific heat of intelligent element material therefor, quality, the rated current intensity of circuit and circuit;
(3) integrating step (1), (2), calculate the sectional area expression formula of intelligent element, build fire isolating switch intelligent element cross section model, determine the cross-sectional sizes of intelligent element.
2. the defining method in a kind of fire isolating switch intelligent element cross section as claimed in claim 1, is characterized in that: the concrete grammar of described step (1) is: the equation (1) of being derived quality and intelligent element sectional area by density formula,
ρ
density=m/v=m/sL
M=sL ρ
density(1)
In formula, s is the sectional area of intelligent element, ρ
densityfor the density of intelligent element material therefor, L is the length of intelligent element, and v is the volume of intelligent element.
3. the defining method in a kind of fire isolating switch intelligent element cross section as claimed in claim 1, is characterized in that: the concrete grammar of described step (2) is: the relational expression (2) listing resistance and intelligent element sectional area,
R=ρ
resistivityl/s (2)
List the relational expression (3) of caloric receptivity and the temperature difference (being exactly phase transition temperature) here,
Q＝cm△T (3)
List the relational expression (4) of joule lenzs law,
Q＝0.24I
2Rt (4)
By (3), (4) simultaneous, obtain relational expression (5),
cm△T＝0.24I
2Rt (5)
In formula, s is the sectional area of intelligent element, and I is the rated current intensity by circuit, the time of disconnecting circuit of t for allowing when overcurrent appears in circuit, ρ
resistivityfor the resistivity of intelligent element material therefor, c is the specific heat of intelligent element material therefor, ρ
densityfor the density of intelligent element material therefor, △ T is 1/2nd of intelligent element material therefor starting temperature of transformation As and phase transformation end temp Af sum.
4. the defining method in a kind of fire isolating switch intelligent element cross section as claimed in claim 1, it is characterized in that: in described step (3), concrete grammar is, quality and the sectional area relational expression of the intelligent element relational expression of resistance and intelligent element sectional area and step (1) obtained bring the relational expression derived in step (2) into, can obtain:
S
2=0.24I
2t ρ
resistivity/ c ρ
density△ T (8),
According to Area Model, the size of design intelligent element,
In formula, s is the sectional area of intelligent element, and I is the rated current intensity by circuit, the time of disconnecting circuit of t for allowing when overcurrent appears in circuit, ρ
resistivityfor the resistivity of intelligent element material therefor, c is the specific heat of intelligent element material therefor, ρ
densityfor the density of intelligent element material therefor, △ T is the starting temperature of transformation As of intelligent element material therefor and 1/2nd of phase transformation end temp Af sum.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201510115394.XA CN104680030A (en) | 2015-03-17 | 2015-03-17 | Method for determining cross section of intelligent element of fire circuit breaker |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201510115394.XA CN104680030A (en) | 2015-03-17 | 2015-03-17 | Method for determining cross section of intelligent element of fire circuit breaker |
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| Publication Number | Publication Date |
|---|---|
| CN104680030A true CN104680030A (en) | 2015-06-03 |
Family
ID=53315063
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|---|---|---|---|
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109612422A (en) * | 2018-12-18 | 2019-04-12 | 吴江变压器有限公司 | A kind of the actual average area of section and measurement of length method of transformer conducting wire |
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| CN1829035A (en) * | 2006-04-10 | 2006-09-06 | 贵阳铝镁设计研究院 | Building electric fire hidden trouble alarm power distribution method and its circuit |
| US20110320169A1 (en) * | 2010-06-28 | 2011-12-29 | General Electric Company | Method and system for detection of collector flashover |
| CN102426632A (en) * | 2011-11-07 | 2012-04-25 | 上海市特种设备监督检验技术研究院 | Heat flux density improved method for safety tongs of explosion-proof elevator |
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2015
- 2015-03-17 CN CN201510115394.XA patent/CN104680030A/en active Pending
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1829035A (en) * | 2006-04-10 | 2006-09-06 | 贵阳铝镁设计研究院 | Building electric fire hidden trouble alarm power distribution method and its circuit |
| US20110320169A1 (en) * | 2010-06-28 | 2011-12-29 | General Electric Company | Method and system for detection of collector flashover |
| CN102426632A (en) * | 2011-11-07 | 2012-04-25 | 上海市特种设备监督检验技术研究院 | Heat flux density improved method for safety tongs of explosion-proof elevator |
Non-Patent Citations (2)
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| "PTC热敏电阻防过流性能浅析";兰石发;《电力系统通信》;19990430(第4期);第43-46页 * |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109612422A (en) * | 2018-12-18 | 2019-04-12 | 吴江变压器有限公司 | A kind of the actual average area of section and measurement of length method of transformer conducting wire |
| CN109612422B (en) * | 2018-12-18 | 2020-11-24 | 吴江变压器有限公司 | Method for measuring actual average cross-sectional area and length of transformer wire |
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Application publication date: 20150603 |