SI9800018A

SI9800018A - The over-voltage varistor protector

Info

Publication number: SI9800018A
Application number: SI9800018A
Authority: SI
Inventors: Vladimir Murko; Bojan Trojar
Original assignee: ISKRA ZAŠČITE d.o.o.
Priority date: 1998-01-26
Filing date: 1998-01-26
Publication date: 1999-08-31

Abstract

The over-voltage varistor protector should provide effective surge protection of electric and electronic devices at extremely high currents for example 250 kA. Together with ordinary automatic fuses it should be mountable without any additional surge protection to a standard available rail (36), particularly the 35-mm DIN rail (36). On the other hand this means that its height or the height of its chassis (33) should not considerably exceed the height of the automatic fuse, while its width or the width of its chassis (33) should not exceed twice the width of an ordinary automatic fuse attached to the specified rail (36). The surge protection according to the invention includes an assembly of specifically shaped varistors (7) inside the chassis (33), which are interconnected by specifically shaped contact surfaces (59, 60). The switching mechanism (15) interacts with an alarming assembly (16) and if required also an remote alarm assembly (17).

Description

Prenapetostni zaščitni varistorski odvodnikOvervoltage protective varistor arrester

Izum se nanaša na prenapetostni zaščitni varistorski odvodnik, ki je predviden zlasti za zaščito električnih in elektronskih naprav pred električnimi preobremenitvami, do kakršnih lahko pride npr. pri udaru strele.The invention relates to an overvoltage protective varistor arrester, which is provided in particular for the protection of electrical and electronic devices against electrical overloads, which can occur e.g. when struck by lightning.

Pri tem je izum osnovan na problemu, kako zasnovati prenapetostni zaščitni varistorski odvodnik, ki naj bi omogočal učinkovito prenapetostno zaščito električnih in elektronskih naprav za ekstremno visoke tokove, npr. tudi do 250 kA, pri tem pa naj bi bil brez vsakršnih dodatnih prenapetostnih zaščitnih naprav skupaj s sicer običajnimi avtomatskimi varovalkami prigradljiv na standardno v ta namen razpoložljivo letev, zlasti npr. na 35-milimetrsko klobučno letev, s tem da naj njegova višina oz. višina njegovega ohišja ne bi bistveno presegala višine ohišja običajne avtomatske varovalke, njegova širina oz. širina njegovega ohišja pa dvakratne širine ohišja običajne avtomatske varovalke, namestljive na omenjeno letev.The invention is based on the problem of how to design an overvoltage protective varistor arrester, which is intended to provide an effective overvoltage protection of electrical and electronic devices for extremely high currents, e.g. up to 250 kA and without any additional overvoltage protection devices, together with the usual automatic fuses, could be fitted to a standard lath available for this purpose, in particular e.g. on a 35 mm hat strip, with its height or. the height of its case would not significantly exceed the height of the case of a conventional automatic fuse, its width or. the width of its casing is twice the width of the casing of a conventional automatic fuse, mounted on said lath.

Eden izmed močnostnih prenapetostnih odvodnikov, ki se za zaščito proti direktnemu udaru strele oz. prenapetosti vse pogosteje uporabljajo pri raznovrstnih električnih napravah, je znan iz DE 42 36 584 Al. Tovrstne naprave naj bi se aktivirale pri udarih strele in drugih električnih preobremenitvah, kadar tok preseže 5 kA. Pri tem pa je njihov odziv razmeroma počasen, in sicer znaša odzivni čas vsaj 100 ns. Zato je potrebna še dodatna zaščita z razmeroma hitro odzivajočimi se varistorji in vmesna filtrska stopnja z ustrezno induktivnostjo ali pa npr. s primemo večjo induktivnostjo vodnikov do ščitene naprave.One of the power surge arresters that protects against direct lightning or shock. surges are increasingly used in a wide variety of electrical devices, known from DE 42 36 584 Al. Such devices are supposed to be activated in lightning strikes and other electrical overloads when the current exceeds 5 kA. However, their response is relatively slow, with a response time of at least 100 ns. Therefore, additional protection with relatively fast-response varistors and an intermediate filter stage with adequate inductance, or e.g. with a higher inductance of conductors to the shielded device.

Nadalje so v praksi že tudi znani varistorski odvodniki proizvajalcev Obo Bettermman, Phoenix (Nemčija) in Kleinhuis (Nemčija), ki vzdržijo udare do 100 kA oblike 8/20 ps. Pri teh napravah so vgrajeni varistorji standardnih oblik in karakteristik, namreč kvadratni varistoiji, katerih izmere so med drugim omejene z izmerami ohišja, v katerem so vgrajeni. Vendar za ekstremno visoke obremenitve v smislu tokovnih udarov pri direktnem udaru strele taki varistorski odvodniki ne zadostujejo. Kot primer lahko navajedemo, daje že pri takoimenovanem razredu B zaščite na vhodih v zgradbe potrebno vgrajevati odvodnike večjih odvodnih sposobnosti ali pa že omenjene občutno dražje kombinacije zaščitnih naprav na posamezni fazi ali vodniku.Furthermore, Obo Bettermman, Phoenix (Germany) and Kleinhuis (Germany) varistor arresters, which withstand shocks up to 100 kA 8/20 ps, are already known in practice. These devices incorporate varistors of standard shapes and characteristics, namely square varistos, the dimensions of which are limited, inter alia, by the dimensions of the housing in which they are incorporated. However, such varistor arresters are not sufficient for extremely high loads in terms of electric shocks in direct lightning strikes. As an example, the so-called Class B protection at the entrances to buildings requires the installation of arresters of higher drainage capacities or the already mentioned considerably more expensive combinations of protective devices at a particular stage or conductor.

Po izumu je uvodoma navedeni problem rešljiv s prenapetostnim zaščitnim varistorskim odvodnikom, ki obsega vsaj en v ohišju odvodnika nameščen varistorski sklop, kot tudi z javljalnim sklopom za identifikacijo okvare sodelujoč odklopni mehanizem, in sicer na ta način, da je v priročnem ohišju običajne in uporabnikom znane oblike, katerega širina ustreza dvakratni širini običajne avtomatske varovalke in ki je prigradljivo na običajno letev za pritrditev avtomatskih varovalk, prednostno na 35-milimetrsko klobučno letev za namestitev običajnih avtomatskih varovalk, nameščen varistorski sklop med seboj preko kontaktnih plošč električno povezanih varistorjev, od katerih je vsak po izumu modificiran in izveden kot pravokotna plošča z zaokroženimi vogali in robovi ter opremljen z zgornjim ovalnim oz. zaokroženim dodatkom in spodnjim ovalnim oz. zaokroženim dodatkom. Pri tem nadalje po izumu z osrednjo odprtino opremljene kontaktne plošče obsegajo vsakokrat po dva kontakta, od katerih eden sega v tisto območje ohišja, ki se nahaja nad vijakom z enakim potencialom, preostali pa v zgornje območje ohišja. Kot varistorji so predvideni selekcionirani oz. med seboj glede na karakteristike usklajeni metaloksidni varistorji, ki so med izdelavo ob upoštevanju vrste drugih tehnoloških in kontrolnih zahtev tudi vsaj starani in trikrat posrebreni. Pri tem nadalje površina v plastičnem ohišju nameščenih priključnih sponk smotrno znaša vsaj 10x10 mm. Omenjeni odklopni mehanizem je osnovan na učinku popuščanja spajke zaradi segrevanja kot posledice trajne električne preobremenitve. Javljalni sklop - namreč sklop za javljanje okvare obsega s spiralnimi vzmetmi in kovinskimi premičnimi kontakti odklopnega mehanizma sodelujoče plastične nosilce, ki so vodljivi v utorih ustreznega vodila, pri čemer vsak nosilec obsega vsaj po eno označbo za regularno stanje, ki je po možnosti zelena, in vsaj eno - po možnosti rdečo - označbo za okvaro. Daljinski javljalni sklop prednostno obsega prečno ploščo, ki je navaljena na skrajšanem kontaktu mikrostikala in ob katero je v primeru okvare naslonljiva glava vsakokrat ustreznega nosilca.According to the invention, the aforementioned problem is solved by an overvoltage protective varistor arrester, comprising at least one varistor assembly installed in the arrester housing, as well as by a fault detection assembly participating a breaker mechanism, in such a way that it is in the convenient housing for ordinary users of a known shape, the width of which corresponds to twice the width of a conventional automatic fuse, and which is mounted on a conventional fuse-mounting bar, preferably a 35-mm fuse-bar for the installation of a conventional automatic fuse, with a varistor assembly interconnected via contact plates of electrically connected varistors each according to the invention is modified and constructed as a rectangular panel with rounded corners and edges, and is provided with an upper oval or a rectangular plate. rounded appendage and lower oval respectively. a rounded addition. Further, according to the invention, the contact openings provided with a central opening comprise two contacts each, one extending into the region of the housing above the screw of equal potential and the remaining to the upper region of the housing. Selected or selected varistors. metalloxide varistors, which are at least aged and silver-plated at least three times during manufacture, taking into account a variety of other technological and control requirements. Furthermore, the surface in the plastic housing of the terminals installed is preferably at least 10x10 mm. The said disconnect mechanism is based on the effect of the solder failure due to heat as a result of permanent electrical overload. Reporting assembly - namely, a failure reporting assembly comprising, by means of coil springs and metallic movable contacts, a disconnecting mechanism of cooperative plastic carriers that are guided in the grooves of the respective guide, each carrier having at least one regular state indication, preferably green, and at least one - preferably red - indication of failure. The remote signaling assembly preferably comprises a transverse panel which is flush with the shortened contact of the microswitch and in which case the head of the corresponding support is restrained in case of failure.

Primer izvedbe prenapetostne zaščitne naprave bo v nadaljevanju opisan na osnovi priložene skice, pri čemer kažejo sl. 1 shematično in v perspektivi ponazoijen primer izvedbe prenapetostnega zaščitnega varistorskega odklopnika po izumu, sl. 2 ohišje in način vgradnje naprave po sl. 1, sl. 3 shematično in v narisu ponazorjen način vgradnje varistorjev v ohišje naprave po izumu, sl. 4 v narisu ponazorjen varistor naprave po izumu, sl. 5 v narisu ponazorjen in v ohišju naprave po izumu razporejen varistorski sklop naprave po izumu, sl. 6 shematično in v perspektivi ponazorjen odklopni mehanizem naprave po izumu, sl. 7 detajl ureditve indikacije okvar po sl. 6, sl. 8 pa ureditev daljinskega javljanja pri napravi po izumu.An example of an embodiment of an overvoltage protection device will be described below on the basis of the accompanying drawing, with FIGS. 1 is a schematic and perspective view of an embodiment of an overvoltage protection varistor circuit breaker according to the invention; 2 shows the housing and method of mounting the device according to FIG. 1, FIG. 3 is a schematic and in outline illustration of a method of mounting varistors in the housing of the device according to the invention; FIG. 4 is a diagram illustrating a varistor of the device according to the invention; 5 is a diagram illustrated and arranged in the housing of the device according to the invention a varistor assembly of the device according to the invention; 6 is a schematic and perspective view of the disconnection mechanism of the device according to the invention; 7 is a detail of the arrangement of the fault indication according to FIG. 6, FIG. 8 is an arrangement for remote sensing of the device according to the invention.

Zahvaljujoč rešitvi uvodoma navedenega problema je po izumu možno računati z zelo hitro in ekstremno učinkovito zaščito, in sicer pri obravnavanem primeru pri električnih preobremenitvah oz. udarih strele do 250 kA z odzivnim časom 6 ns. Pričujoči primer po sl. 1 - 8 obravnava napravo, kije pri 250 kA (pri 8/20 ps ali pri še hujšem standardnem udaru 25 kA pri 10/350 ps) zmožna nuditi prenapetostno zaščito električnih in elektronskih naprav pri udarih strele ali drugih prenapetostih ter s tem v večini možnih aplikacij nadomestiti naprave, znane iz stanja tehnike.Thanks to the solution of the aforementioned problem, according to the invention, it is possible to count with a very fast and extremely effective protection, in the present case in case of electrical overloads or lightning strikes up to 250 kA with a response time of 6 ns. The present example of FIG. 1-8 deals with a device capable of providing overvoltage protection of electrical and electronic devices at lightning or other overvoltages at 250 kA (at 8/20 ps or at an even worse standard shock of 25 kA at 10/350 ps) and thus in most cases applications to replace devices known in the art.

Pri pričujoči napravi je problem hitrega reagiranja zaščite odpravljen z vgradnjo takoimenovanih metaloksidnih varistoijev 7, ki pa so oblikovani in obdelani na poseben način. Razen tega je zelo zaželeno, da so varistoiji 7 med seboj izjemno tudi dobro usklajeni glede na njihove karakteristike, razen tega pa tudi usklajeni s spet med seboj dobro usklajenimi zaščitnimi varistorskimi napravami na energetskem napajanju.In the present device, the problem of rapid reaction of protection is eliminated by the installation of the so-called metal oxide varistoi 7, which are, however, shaped and treated in a special way. In addition, it is highly desirable that varistoys 7 be exceptionally well matched to their characteristics, in addition to being matched to well-matched protective varistor devices on the power supply.

Pogoji v smislu visokih tokov, kakršnim so izpostavljene tovrstne naprave, so obvladljivi z uporabo ustreznih elementov, zlasti razmeroma velikih priključnih sponk 18, 19 (sl. 1), prednostno večjih kot npr. 10 x 10 mm. Pri tem, so mišljeni tako fazni vodnik 20 in njegova priključna sponka 18 ter zemeljski vodnik 21, kot tudi posebna mehanska konstrukcija 14, ustrezno konstruirane notranje nosilne kontaktne kletke 23, 24, notranji preseki vodnikov v kovinskih trakovih 25, 26 in prevodih 27 ter posebna konstrukcija odklopa v primeru uničenja, razen tega pa tudi sklop 16 za javljanje napak in sklop 17 za daljinsko signalizacijo napak. Pri tem pomembno vlogo igra kakovostna obdelava galvaniziranih, varjenih in spajkanih lokacij. Ker gre za ekstremno visoke tokove, so zahtevani posebni tehnološki in kontrolni postopki.Conditions in terms of high currents to which such devices are exposed are manageable by the use of suitable elements, in particular relatively large terminal blocks 18, 19 (Fig. 1), preferably larger than e.g. 10 x 10 mm. In this context, both the phase conductor 20 and its terminal block 18 and the earth conductor 21 are intended, as well as the special mechanical structure 14, the internal support contact cells 23, 24, the inner cross sections of the conductors in the metal bands 25, 26 and the conductors 27, and the special the design of the tripping in the event of destruction, in addition, the fault reporting unit 16 and the remote fault signaling assembly 17. High-quality machining of welded, welded and brazed locations plays an important role in this. Because these are extremely high currents, specific technological and control procedures are required.

Ohišje 33 je izvedeno iz visokoodpome plastike in je v danem primeru zgolj nekoliko, komaj opazno višje od ohišja običajne avtomatske varovalke. Vendar pa je v danem primeru ohišje 33 široko natanko toliko kot dve običajni avtomatski varovalki, tako da ga je možno brez nadaljnjega vgraditi na običajno, standardno 35-milimetrsko klobučno letev 36 (sl. 2) poleg omenjenih varovalk.The housing 33 is made of high-resistance plastic and, in the case in question, is only slightly, barely noticeably higher than that of a conventional automatic fuse. However, in the present case, the housing 33 is exactly the same width as the two conventional automatic fuses, so that it can be fitted without further extension to the conventional, standard 35 mm hat strip 36 (Fig. 2) in addition to said fuses.

Prav ta značilnost, ki je v skladu z uvodoma zastavljenim problemom, je možna zahvaljujoč presenetljivo učinkovitemu posegu v varistorski sklop. Varistorji 7 so namreč izvedeni v obliki, kakršna je prikazana na sl. 3, tako daje prostor, ki je na voljo v ohišju 33, kar najbolje izkoriščen. Sicer razpoložljive izmere 37 x 51 mm je možno preseči, če so varistorji 7 kot pri napravi po izumu izvedeni v obliki pravokotne plošče z zaokroženimi vogali in robovi, opremljene z ovalnim oz. krožnim zgornjim dodatkom 41 ter ovalnim oz. krožnim spodnjim dodatkom 143. Na ta način je možno kar najbolj učinkovito slediti ugotovitvi, da je največja odvodna moč varistorja 7 na enoto površine največja pri okroglem varistoiju.This characteristic, which is in line with the problem set out above, is possible thanks to the surprisingly effective interference with the varistor circuit. Namely, the varistors 7 are made in the form shown in FIG. 3, thus giving the space available in the housing 33 the best use. Otherwise, the available dimensions of 37 x 51 mm can be exceeded if the varistors 7, as in the device according to the invention, are made in the form of a rectangular panel with rounded corners and edges, equipped with an oval or. circular upper appendices 41 and oval respectively. 143. In this way, it is possible to follow as efficiently as possible the finding that the maximum drainage power of varistor 7 per unit area is greatest at round varisto.

Vogali in robovi varistoija 7 so zaokroženi, ker bi sicer na teh mestih prihajalo do trikratne poljske jakosti, kar bi lahko povzročilo uničenje odvodnika. Iz istih razlogov je (sl. 5) kontakt 53 pomaknjen proti fazi v prostor blizu vijaka 54, ki ima isti potencial. Pri 60 kA varistoiju 7, ki je prikazan na sl. 5, je en kontakt 55 pomaknjen v prostor pokrova 56 ohišja 33, drugi kontakt 53 pa v prostor nad vijakom 54. Na ta način je en varistor 7 zmožen odvesti 60 kA pri 8/20 ps.The corners and edges of varisto 7 are rounded because otherwise these areas would produce three times the field strength, which could lead to the destruction of the arrester. For the same reasons (Fig. 5), the contact 53 is shifted towards the phase in the space near the screw 54, which has the same potential. At 60 kA varisto 7 shown in FIG. 5, one contact 55 is moved to the cover space 56 of the housing 33 and the other contact 53 is moved to the space above the screw 54. In this way, one varistor 7 is able to discharge 60 kA at 8/20 ps.

Takemu konceptu odvoda 60 kA in 5 x 60 kA so prirejene tudi kontaktne kovinske plošče 59, 60 varistorja 7, in sicer tako v smislu izbire materiala, oblike in presekov. Ker so kontaktne plošče 59, 60 izrazito zaokrožene in v sredini opremljene z odprtino, ki omogoča prevod zgolj skozi varistorsko keramiko, se ustrezno zmanjša preostala vrhnja napetost prehodnega pojava na varistorju v času motilnega impulza. Taka rešitev v primeijavi s tistimi pri konkurenčnih izdelkih, kjer se uporabljene polne ali zgolj perforirane plošče, daje bistveno boljše rezultate. Ureditev omenjene enotne odprtine namreč daje boljše rezultate zaradi neizogibnega staranja varistoija, ki je posledica prenapetostnih tokovnih in napetostnih udarov. Pri prednostnih izvedbah je kontaktna površina same varistorske keramike trikrat srebrena. Sicer pa so varistoiji 7 izvedeni iz keramične mase posebnih lastnosti, ki je razen tega tudi obdelana na poseben način. Tako je zagotovljen odvod pri velikih udarih toka in majhen tok v povratni smeri, namreč strokovnjakom znan tkzv. lekeage current. Varistorji za 60 kA odvodne tokove so tudi starani, in sicer že v času samega proizvodnega procesa.The 60 kA and 5 x 60 kA discharge concept are also adapted to the contact metal plates 59, 60 of the varistor 7, both in terms of material selection, shape and cross sections. Since the contact plates 59, 60 are distinctly rounded and in the middle are provided with an aperture that allows conduction only through varistor ceramics, the residual peak voltage of the transient phenomenon on the varistor during the jamming pulse is correspondingly reduced. Such a solution, when compared to those of competing products, where full or only perforated panels are used, produces significantly better results. The arrangement of the aforementioned single orifice gives better results due to the inevitable aging of varistoi, which is the result of surge current and voltage shocks. In preferred embodiments, the contact surface of the varistor ceramic itself is three times silver. Otherwise, the varistoys 7 are made of a ceramic mass of special properties, which is also treated in a special way. In this way, a drainage is provided in the case of large shocks and a small flow in the reverse direction, namely known to those skilled in the art. lekeage current. Varistors for 60 kA drainage currents are also aged, during the production process itself.

Odklopni mehanizem 15 (sl. 6) s pomočjo sklopa 16 za javljanje napak (sl. 2) služi za odklapljanje v primeru okvare posamezne varistorske skupine 86, 87, 88 in obsega globoko v pokrov 56 ohišja 33 pomaknjene premične dele, in sicer v danem primeru tri spiralne vzmeti 67, tri kovinske premične kontakte 70 posebne oblike, velikosti presekov in materiala z izbrano galvansko prevleko. Razen tega so v danem primeru na voljo trije plastični nosilci 73, 74, 75, od katerih je vsak opremljen z označbama 76, 77 (sl. 7). Pri tem je označba 76 lahko npr. zelene barve in označuje regularen način delovanja, označba 77 pa npr. rdeče barve in označuje okvaro. Regularno premikanje plastičnih nosilcev 73, 74, 75 kontaktov 70 je omogočeno zahvaljujoč trojnemu vodilu 79 z utori 80, v katerih so na voljo ustrezna prozorna okenca. V primeru okvare varistorske skupine 86, 87, 88 trajen tok, ki teče skozi napravo, segreje varistor 7 in na njem prisotne kontakte na določeno temperaturo, pri kateri popusti spajka, s čimer se sproži odklopni mehanizem 15, namreč pripadajoča vzmeti 67 in premični kontakt 70, zaradi česar se ustrezen oz. vsakokrat pripadajoč plastični nosilec 73, 74, 75 premakne v položaj, ko je npr. skozi prozorno okence namesto pred tem zelene označbe 76 odtlej vidna rdeča označba 77.The tripping mechanism 15 (Fig. 6), by means of a fault reporting assembly 16 (Fig. 2), is used for tripping in the event of a failure of an individual varistor group 86, 87, 88 and extending the movable parts deep into the housing 56 of the housing 56 in the case of three spiral springs 67, three metal movable contacts 70 of special shape, cross-sectional size and material with electroplating. In addition, three plastic supports 73, 74, 75 are available in each case, each of which is provided with indications 76, 77 (Fig. 7). In this case, the designation 76 may e.g. green and indicates the regular mode of operation; is red and indicates a malfunction. The regular movement of the plastic supports 73, 74, 75 of the contacts 70 is enabled thanks to the triple guide 79 with grooves 80 in which suitable transparent windows are available. In the event of a defect in the varistor group 86, 87, 88, a continuous current flowing through the device heats the varistor 7 and contacts thereto at a certain temperature at which the solder loosens, thereby triggering the tripping mechanism 15, namely the associated springs 67 and the movable contact 70, making it appropriate or in each case, the associated plastic carrier 73, 74, 75 moves to a position when e.g. through the transparent window instead of the green marking 76, the red marking 77 has been visible since then.

Daljinsko javljanje okvare je s pomočjo sklopa 17 za javljanje napak (sl. 1) možno v danem primeru vzpostaviti na ta način, da plastični odklopni nosilci 73, 74, 75 (sl. 8) pri odklopu ob premiku z glavo 125 zadenejo ob posebno oblikovano prečno ploščo 116, kije navarjena na skrajšanem kontaktu 118 mikrostikala 122.With the help of the fault reporting assembly 17 (Fig. 1), the remote fault detection can be optionally set up in such a way that the plastic disconnecting brackets 73, 74, 75 (Fig. 8) hit the specially shaped disconnect head 125. the transverse plate 116, which is welded to the shortened contact 118 of the microswitch 122.

Claims

PATENT APPLICATIONS

A surge protective varistor arrester comprising at least one varistor (7) housed in a housing (33), as well as with a fault detection assembly (16), a cooperating tripping mechanism (15), characterized in that it comprises in the housing (33) , the width of which corresponds to twice the width of the normal fuse box body and the height at least approximately the height of the ordinary automatic fuse body and which is mounted on a conventional fuse holder (35), preferably a 35 mm hat fitting (36) for the installation of conventional automatic fuses, varistor assembly interconnected via suitable contact plates (59, 60) of electrically connected varistors (7), each of which is at least essentially a rectangular panel with rounded corners and edges, and provided with an upper oval or an oval. rounded accessory (41) and lower oval or. rounded appendix (143).

2. Overvoltage protection varistor arrester according to claim 1, characterized in that, with a single central opening, the contact plates (59, 60) each comprise two contacts (53, 55), one contact (53) extending into that region of the housing (33) above the bolt (54) with equal potential and the remaining contact (55) into the upper region (56) of the housing (33).

3. Overvoltage protective varistor arrester according to claims 1 and 2, characterized in that the varistors (7) are implemented as selected or. harmonized metal oxide varistors (7) and aged and silver-plated three times during manufacture.

4. Overvoltage protective varistor arrester according to claims 1-3, characterized in that the surface in the plastic housing (33) of the terminal blocks (18, 19) is at least 10 x 10 mm. '

5. Overvoltage protective varistor arrester according to claim 1, characterized in that the disconnect mechanism (15) is based on the solder failure due to heating as a result of a more permanent electrical overload.

6. Overvoltage protective varistor arrester according to claim 1, characterized in that the detector assembly (16) comprises cooperatively preferably plastic supports (73, 74, 75) with coil springs (67) and metal movable contacts (70) of the disconnect mechanism (15). which are guided in the grooves (80) of the guide (79).

7. Overvoltage protective varistor arrester according to claim 6, characterized in that each carrier (73, 74, 75) comprises at least one indication (76) for the regular state and at least one indication (77) for the failure.

8. Overvoltage protective varistor arrester according to claim 7, characterized in that the carrier (73, 74, 75) comprises at least one green indication (76) for the regular state and at least one red indication (77) for the failure.

9. Overvoltage protection varistor arrester according to claim 1, characterized in that a remote signaling assembly (17) is provided, comprising a transverse plate (116) which is welded to the shortened contact (118) of the microswitch (122), and in which case the leaning head (125) of the corresponding support (73, 74, 75) is defective.