HUE025641T2 - Fuse and circuit breaker comprising such a fuse - Google Patents

Description

FUSE Am CIRCUIT BREAKER CÜMPRISIMï SUCH A FUSE

This kveatioa relaies to a -fese «©inpri-skg m taskafing Bar and at least one fuse strip- wound oaks tais fear. The fcsventa further elates to a combined switch comprising at least one such Rise, The field of the invention is that of high voltage fuses provided on coeMmá switches. la particular, fee invention relates to a high voltage fuse intcuded to protect MV&Y' (medium voliage/low voltage) cables and distribution transformers.

The fuse can provide this protecta itself, or fey feeing, associated with a ootnbiaed switch. In this case, it is provided with a striker whisk causes the automatic opening of the switch following the operation of the fuse. The association of the two devices, fuse sad switch, is characterised by a transfer current, for which they exchange the cut-off function; above this value, the current is interrupted only by the fuses, under tins value it is interrupted on one phase by fee first fuse which melts, and by the switch on the two other phases.

Ad vaoiageous-l>s fee &se must have a quiek response, fey cutting off when the current: increases beyond a pro-determined value, la the event of an over-current or short-circuit* the fuse is cat. by foskm of the fuse elements, and even faster fee hágta'the over-current is. A primary component of the fuse is therefore fee fuse element, which conventionally is wound onto as insulating bar arranged in fee body of fee fuse. The fuse element is subjected to an increase is temperature proportional to fee intensi ty of the current feat is passing through it. In normal operation, fee temperature of the fuse element is less than its melting temperature and the current circulates normally. In the event of over-current, the temperature of fee fuse element exceeds fee melting temperature in one or several points of the fuse element, which melts at least partially, and fee circulation of fee current is eut off, US-A-2O07Ai 159291 describes a fuse, wife one or several fuse elenrents arranged m m insulating central fear. Each luse element Includes a main portion and a plurality of narrow sections arranged in series over ils entire length. These narrow sections oiler a resistance fent is higher than the.rests portions to the passage of the current, their temperature therefore increases until melting when fee intensity of the current reaches a sufficient value, However, the response of fee fuse is not always satisfactory at certain critical intensities, for which fee cut-off time is too slow. GB-A-2 184 301 describes a fuse comprising a fuse element On this element are delimited, on the one hand, a current portion provided wife several narrow sections of a first typ.« and, on the other hand, and end portion provided with one or several narrow' sections of a Second type. The response of fers fuse is not Tasi enough to be effective, in particular for so-called « intermediate » intensities, corresponding to a melting time between IG milliseconds and 1 second.

The purpose of this invention is to propose a fuse having: a faster response, in particular for currents feature close to the transfer current when it is associated wife a switch.

To this effect, the invention has for object a fuse comprising a tubular body, at least one insulating bar arranged in the tubular body along a longitudinal axis of the tubular body, and at least one fuse strip with constant thickness, arranged on the bar and extending between the longitudinal cads of fee fuse, wife the strip comprising segments of amimurn width and several narrow sections arranged along: its longitudinal direction. each, narrow section having a geometry defined fey its niinimum width and its length, wherein the narrow sections are at least of two different types and include at least one narrow' section of a feist type, which has a füst naniKsttm width, and at least one narrow section of a second' type, which has a second antrimum width that is diffèrent from the first minimum width. This fee is characterised in that the narrow sections are regularly spaced along the fee strip, with an alternation of narrow sections of the first type and of narrow sections: of the second type.

As such, a fee element comprising zones of narrow sections of different types, having different minimum widths, and arranged in alternation according to its longitudinal direction, makes it possible to create a fuse having .an improved response, fast regardless of the intensity for which the fee most be cut off,' The response of the fee is as. particular improved, for so-called intermediate fault intensities, for which the enfeoff time is between 10 milliseconds and 1 second.

Other advantageous characteristics of the invention, taken separately or In combination are specified is claims 2 to 14,

The invention also has for object a combined switch comprising at least one fuse such as mentioned hereinabove.

The invention shall· he heiter tindersiood whs® reading the following description provided solely as a nors-restrkted example asd snade in reference to the drawings whereon: - figure 1 is tt perspective view of a fuse in accordance with the invention; - figure 2 is a cross-section of the fuse in the plâtre II of figure ! ; - figure 3 is a cross-section of the fuse in die plane ill of figure 2, with a portion of its central bar seen from the exterior; - figure 4 is an elevations! view ci a fuse element provided os the fuse m figures 1 to 3; - figures 5 sad 6 are view on a higher scale of the details V and Vi in figure 4; - figures ?, 8,9 and 10 are eievatiotnti views and of details analogous to figures 4 to d for a second embodiment of a fee element providing a fee in accordance with the invention, and » figuoc Í1 is a graph showing the response of the fuse of figures 1 to 6.

Figures 1, 2 and 3 show a fee ! itt accordance with tite invention. Figure I is art overail view of the fee I. Figures 2 and 3 show the fuse I, respectively as a trmsverse cross-section and as a longitudinal cross-section.

The fuse 1 comprises a substantially tubular fee body 2, defining a longitudinal axis X~X', The body 2 is made of an insulating material, more preferably of porcelain.

At each of the longitudinal ends la or lb of the fuse 1 Is arranged a capsule 3a or 3b, able to conduct the electric cutveht, and made mors preferably of metal One of the capsules 3a of 3b can include a striker set 9 provided with a spring 91.

At the interior ofth« tubular body 2 is arranged a central bar 4, which extends between the two ends la sad lb of tite fuse, parallel to the axis X-X'. The bar 4 .is made of an insulating material more preferably of ceramic. As can be seen in figure 2, the bar 4a has a transverse section with star with, six branehex, When the bar 4 k positioned inside the body 2, its central and fegirndmal axis X4 coincides with the axis X-X1. The intermediate volume 8 between the bar 4 and the body 2 of the fee I k filled with stmd, not shown. ïn an alternative embodiment not shows, the fuse 1 can comprise two concentric bars arranged in the body 2.

Between each capsule 3 a and 3b and the bar 4 is positioned an eiectricaiiy eondstctive contact part, respectively 6a and 6b, snore preferably made of metal The contact parts 6a and 6b each include six tabs 61a and 61b. which extend radially in the direction of the body 2 and which make it possible to connect the fuse elements. The contact parts 6a and 6b also include elements for positioning 62a and 62b, which allow for a correct a&gsmem wish the bar 4, and electrical contact strips 6:3a. and 63b, Each contact part 6a and 6b is linked to the bar 4 by art element for fastening, respectively 'Ha and 71b.

The bar 4 comprises a central through-hole 41 of snhstautially circular shape, whereat is housed a spiralling fuse wire 22, also called striker wire. On the side oriented towards the end l a of the fuse 1, she striker wise 22 is connected to the striker set 9 by a metal tube 23 which in parslcsdar eosnprises: crimping aoues m order to snaintain the striker wire 22, On the side oriented towards the end lb of the fuse 1, the striker wire 22 is connected to one of the contact strips 63b.

Wm aa over-omrent causes the melting of the fuse 1, the mobile portion of the: striker set 9 is released and actuates she mechanism of the switch and/or snakes it possible to report on the stats of she fuse, A conductive fuse element 110 is spiralling wound onto the bar 4, between she two contact paris 6a and 6b. In practice, the fuse elesnem 110 is a fuse strip, made of silver (Ag). in figure 3, a central portion of the bar 4 is shown as an exterior view; .in.order to show the winding of she atrip 110 onto the bar 4. The ends of the strip 110 are connected to the tabs 61 a arid 61b of the contact pasts 6 a and 6b, which are themselves connected to She respective capsules 3a and 3b. The connections between the conductive parts are carried oui via welding, or any osher ksrown means,

The fuse strip has a constant thickness el 10, with -his thickness being measured perpendicularly to she plane of figures 4 to 6, Le. according to a radial direction in relation to the ax is X-X* irs wound configuration of the strip 1:10 onto the bar 4 , X I10 denotes a longitudinal axis of the strip 110, with. Shis axis besag rectilinear m the configuration, of figures 4 to 6 and spiralling in the configuration of figure 3,. The ship 110 has a mmdsnum width 1110, measured pespendiesriariy to its thickness el 10 and to the axis XI10, os several segments 111 distributed over the length of the ship 110, The segments 111 are separated by narrow sections: 112 and 113 of two different type«.. The narrow sections 112 and 113 are regularly spaced along the strip 110, sceos'ding So its longitudinal axis XI IS. More precisely, as tat in figure 4, the narrow sections Î12 and 113 are distributed in attensadon along the ship: 110 and are separated, i,e.. they do not overlap.

As can be seen in figure 5,. each section 112 of the first type has iwo recesses I12 a and 112b of which the edge is so arc of cirele, symmetrically opposite in relations to the axis X110.

As can be sees* in figure 6, each section 113 of the second type has two recesses 113a and 113b, each of a substandally recfangsiim· shape, symmetrically opposite in relation to the axis XI10.

In what follows, a length of a port ion of the fuse strip is sneasared parallel to its longitudinal axis.

The recesses 113a and 113b have a length LI 13 greater than She length L112 of the recesses 112a and 112b, The minimus» width /113 of the ship 11Ö on a narrow section 1.13 of the second -type is greaser shast the minimum width /112 on a narrow section 112 of the first type. More precisely, the ratio of thèse widths 4§ i. s t &. is between 1.1 and 1.4. in practice, the narrow sections ! 12 of the first type -sie more num«foas than the narrow sections 1 1 3 of the second type. For example, as can he seen m figure 4, the strip ï 10 comprises « succession of eight sections 112, then one section 113, and so on in alternation along the strip Π0, Between the narrow sections 152 and i 13, there are segments ΠI of a maximum width /1 10. hr art alternative embodiment not showu, the strip 1 Id can include a .succession of six, sevea or nine sections 312 between two sections 113, and so on in alternation along the strip 110. Hie strip 110 does not comprise a fast extended portion provided with sections 112 and a second extended portion provided with sections 513» without alternation between àe tmrow sections of different types, as is the case in GB-Ä.-2 Í 84301.

Figures '7, fe, 9 and 10 show a second emhodunent of a fuse strip 2.10 which can be provided oa a fuse according to the invention. 'The fuse strip 210 has a constant thickness, with this thickness being measured perpendicularly to the plane of figures ? to 10, i.e. according to » radial direction hi relation to the axis X-X? in vsmnà configuration of the strip 210 onto the fear 4, X2ÍQ denotes a. longitudm&i axis of the strip 210, with this axis being rectilinear is the configuration of Sgures 7 to 10 and spiraling in a configuration similar to that of figure 3, The strip 210 has a maximum width 1210, measured perpendicularly to its thickness and to the axis X21ti, on several segments 211 distributed over the length of the strip '210. The segments 211 are separated by narrow sections 212, 213 and 2 i4 of three différés! types, which are regularly spaced along the strip 210, according to its longitudinal axis X210. More precisely, as shown irt figure 7, the narrow sections 212, 213 and 214 are separated in alternation along: the strip 210 and are separated, ie. they do not overlap.

As can be seen in figure i, each section 212 of the first type has: two recesses 2:12a and 212b of which the edge is in an are of circle., synimenieally opposite la relation to the axis X210.

As can be seen in figure 9, each section 213 of the second type has two recesses 213 a and 213b, each of substantially recumgttiar shape, sytntnetrically opposite ih relation to the axisX2I0.

As can be seen in figure 10, each section 214 of the third type has -wo recesses 214a and 214b, each of substantially rectangular shape, symmetrically opposite in relation to the axis X.210.

The reeesses 213s and 213b have a length 1,213 greater than the length 1.212 of the recesses 232a and 212b. The minimum width /213 of the strip 210 on a narrow section 213 of the second type is greater than the maximum width /212 oh a narrow section 212 of the first type.

The recesses 214a and 214b have a length 1214 greater than the length L213 of the recesses 213 a and 213b of a nmow sec tion 213 of the second type. The minimum width /214 of the strip 210 om a narrow sect ion: 214 of the third type is greater than or equal to the mittimutn width /213 on a narrow section 2 i 3 of the second £?H ¢214. type. In particular, the ratios of the minkuum widths ^12 aa(j /212 are between 1,1 and 1.4. In additioa, the ¢214 ratio £213 is between 1 and 1.4.

In praetke, the narrow sections 212 of the first type are more numerous than the narrow sections 213 of the second type, and the narrow sections 213 of the second type are themselves more numerous than the narrow sections 214 of the: third type. For example, m can be seen in figure 7, the strip 210 comprises a succession of seven sections 212, ihen one: section 213, and so on. Moreover, one section 213 out of seven is replaced with a section 214. Between the narren» sections 212,213 and 214, ate found fee segments 211 of raaxaatsn width /110. la an. alternative embodiment sot show,. the strip 210 cap include a succession of six, eight or sechs» 212 'between two sessions 2 D or 214, ansi so onin alternation along the strip 210. fe normal operation of the fese 1, the temperámé of the fee elements focreases via fee -fettle effect, until a vaké at which it stabilises, in particular, tins Joule eiïect «estes m increase in temperature which varies at various points of she fuse strip 110 or 2 Í 0.

As such, the particular configuration of a fuse strip HO or 216 according to the invention tsakes it possible to favour certain melting zones, as the narrow sections 112,1! 3, 212, 213 and 214 do not dissipate the beat as well as segments 1 11 sad 211. Indeed, the geometry of the narrow sections influences their heat exchanges with the hear environment. The various sections of the same type, having identical heat exchanges, tnelt substantially at fee same time in different points on fee fee strip, with this time required for melting depending on the over-current which is circulating in the fuse strip and causes it to heat. For example, for a width and a length of section that: me identical, a recess in the shape of an are or circle dissipates the hoar better than a recess of teeimsgolar in shape, as fee section comprises more material. However, fer a very high Intensity, the mitnmum width of fee narrow seeiion is a predominating: parameter in Iront of the shape of fee recess, as fee section first melts in its cento, and not homogeneously.

As such, when an over-current occurs, esriaib sections are able to melt faster than others. When the strip comprises a single type of narrow section, its e cut-off time ' cut-off intensity » response curve shows a given aspect By combining different types of narrow sections, a response curt'« is obtained which is the superposition of each of the response curves corresponding So each of fee sect ions.

At the highest intensities, corresponding to a very reduced cut-off rime for the fuse, fee- sections of which the minimum width is the lowest melt first, in the embodiments described, this corresponds to fee narrow sections of the first type 112 and 212. When the over-current is less, with a cut-off time slightly higher, fee length and fee particular geometry of the sections come into play. As such, wife their rectangular recesses and their longer length, the narrow sections 113, 213 and 214 of the second and third types are able to melt before those of the first type 112 and 212. The operation of the fuse 1 -is as such mack' faster in a particular range of intensities.

In practice, a strip according to fee first etrlhodimcnt is simpler to manufacture, as it requires & reduced number of machunng author forming operations for only two types of different- narrow sections, while a strip according to fee emlxfoimeni confiasses feme different types of nattes w sections but makes It possible to obtain a different response curve.

Alternatively, fee strip can comprise more than three ripes of different narrow sections, although feat makes itmore complex to manufacture.

According to another alternative embodiment, the geometries, mMumm widths, lengths and shape of recesses of fee different types of narrow sections can vary. For example, in the second eutbodiment, the narrow sections of the third type have a minununt width and a length feat are greater than fitosé of the narrow sections of the second type, Aiternati vely , the narrow sections of the third type ctm have an identical minimum width.

Moreover, a recess can have a triangular, elliptical or toothed shape, or my other geometry.

Claims (8)

1. Figure 11 shows a graph showing the operation of the fuse i provided with the fuse strip 110. This? fuse 1 Is la accordance with the first embodiment described hereinabove ia liaison with ligures 1 to 6. The graph of figure 11 shows the cid-of tin® « t » ia seconds (s), showmen the Y axis, according to the intensity «T » of the fault current in amperes (A), shown on the X axis, according to a logarithmic· scale. The curve €1 shown as a solid line corresponds to the behaviour of a fuse provided with a strip comprising only narrow sections of the first type, similar te 112, regularly spaced, along this strip. The curve C2 shown as. a. dotted line corresponds to the behaviour of the fuse 1 provided with a strip 110, comprising ia alternation eight arrow sections of the fast type 112 and one taetro-w section of the second type 113, and so on alternation along the strip 110. In practice, the cut-off time of the fisc 1 In accordance with the Invention is reduced for the so-called « irttennesliate « intensities, corresponding to a melting lime between 10 milliseconds and 1 second, without modifying or very little the response of die fuse 1 for lew intensities:, Córrespónáhrg to a melting time greater than or close to 10 seconds. The cut-off time corresponds to the melting of the narrow sections, of a specific type, aeeordmg to the fault intensity eurreni OLYABéBÍETOSlYÉK ÉS ILYIN ÖLYAÖÖBIZTGSÍl'ÉKÖT TARTALMAZÓ ÁRAMKÖRI MEGSZAKÍTÓ SZABABÂ1.MI IGÉNYPONTOK
2. 2. Az 1. ígenypoat szefímti solvadőbíztosíték, azzal jellemezve, hogy a feiztosílékszalag (11Ö; 210} váltakozva tanakuïz több első típusú keskeny szakaszt (M2; 212) két második típusú keskeny szakasz U 13:213} között.
3. 3. Az előző igénypontok bármelyike szerinti olvadóhiztosíiék, stzzal jeMemezve, hogy a feiztosíiékszaíagbas (110; 2ÍÖ) egymást kővetően van elhelyezve 1>~Ú első típusú keskeny szakasz (112; 212), majd egy második típusú keskeny szakasz (M3; 20), ás ez a mimázat ismétlődik a bizíoslíéksstalag (110; 210} mentén.
4. 4. Az előző igénypontok bármelyike szedőd olvadébíztosíték, azzal jellemezve, hogy a oiztositekszalagban (MO; 210} egymást követően vtnr elhelyezve ? vagy & első típusú keskeny szakasz (M2; 212}, majd egy második típusú keskeny szakasz (M3; 213), ez a mintázat ismétlődik a bizíosítékszaíag (110; 210} mentés.
5. 5. Az előző igénypontok bármelyike szerinti olvadóbiztosílék. azzal jellemezve, hogy az első típusú keskeny szakasz (132: 212) minimális szelessége (Cl Í2; £212) kisebb, mint a. második típusú keskeny szakasz (M3; 213} mimmálls szélessége (O13; £213), ahol a második minimális szélesség és az első minimális szélesség aránya ~~j 1,1 és 1,4 kézé esik. ő. Az előző igénypontok hsítmelyíke szerinti olvadóbíztösíték, azzal jellemezve, hogy mindegyik első típusú keskeny szakasz (112 ; 21:2} tartalmaz legalább egy mélyedést ( 112a, 112b; 2 í 2a,. 2 Î2h}, amelynek az ele körív alakú, ?. Az előző Igénypontok bármelyike szerinti ôlvadôbiztoâïték, azzal jellemezve, hogy mindegyik második típusú keskeny szakasz (M3: 233) tartalmaz legalább egy mélyedést (M 3 a, 113b: 213&, 213b), asuely iéuyegéixm téglalap alakú, S, Az előző igénypontok bármelyike szerinti olvadóhiztositék, azzal jellemezve, hogy az első típusú keskeny szakasz (112; 212} hossza (L112; L212) kisebb, mini a második típusú keskeny szakasz (M3; 213} hossza (L113; L233).
6. 9, Az előző ígényponksk bánnelyike szerinti olvadóbiztosíték, azzal jellemezve, hogy a bíztosítékszalag (210) tartalmaz legalább egy harmadik típusú keskeny szakaszt (214}, amelynek harmadik minimális szélessége ((214) van, amely eltér az első és második ílpttsú keskeny szakaszok (212, 213) minimális szélességétől (£212, £213), továbbá ahol a harmadik minimális szélességnek m eísö mmimáíís ;sÄssdgh«2- visaeayitoi asâsya 1,1 és 1,4 közé esik. 18. A 9< Igénypont szerinti olvadóbiztositék, azzal jellemezve, hogy a h&amp;rm&amp;dik.típusú keskeny szakasz (214) legalább «gy mélyedés? (214®, 214b) fartstoaz, amely lényegében téglalap alakú, IL A 9. vagy 10, igénypeatmktiolvadóbizíosMc, ass®a! jellemezve, Imgy a urásodík: típusú keslomy szakasz (213) minimális szélessége (€213) legfeljebb akkora, mint a .harmadik típusé keskeny szakasz (214) minimális szélessége (£214), és a második típusú keskeny szakasz (213) hossza (L2I3) legfeljebb akkora, jrdnt a harmadik típusú keskeny szakasz (214) hossza (1,214), és a bosszúságok (L213, L214) sem egyenlők abban .az esetben, .amikor a szélességek (£213, £214} egyenlők, továbbá ahol a harmadik mínímálk szélességnek az első minimális szélességhez viszonyított aránya 1 és 1,4 közé esik Î2. A 9-11. igénypontok Mrmelyike szerinti olvaáőbíztosíték, azzal jellemezve, hogy a biztosítékszaiag (118; 210) nagyobb szántban tartalmaz első típusú keskeny szakaszokat (112;. 212), mint második típusú keskeny szakaszokat (11.3, 21.3), és adott, esetben nagyobb számba« tartatom: második típusú keskeny szakaszokat (213), mint harmadát típusú keskeny szakaszokat (21.4). 13. A 9-12. igénypontok 'bármelyike- szerinti olvadohirtosíték, azzal jellemezve, hogy a bklGsítékszalagbao <1 W; 218) váltakozva egymást követi hét-nyolc első típusú keskeny szakasz (112; 212), Majd egy .második, típusú keskeny szakasz (113; 213) &amp; biztosííékszalag (118; 210} mentén, továbbá ahol a hét második típusú keskeny szakasz <313; 213} közöl az egyik egy harmadik típusú keskeny szakasszal (214) van helyettesítve.
7. 14. Az előző igénypernek bármelyike szerinti olvadóbizíositék, azzal jellemezve, begy az első típusú keskeny szakaszok és a második típusú keskeny szakaszok, valamint adott esetben a harmadik típusú keskeny szakaszok egymástól elkülönülnek.
8. 15. Kombinált kapcsold, azzal jellemezve, hogy legalább egy, az előző igénypontok bármelyike szerinti olvaáóbiztosltékot (I) tartalmas.