baber/WOPTO huggingface dataset:
Patent HU-201114-B (HU)
Title: Process for producing treponema hyodysenteriane bacterin
Inventor: PARIZEK E RICHARD
IPC: C12N1/20
Filed: 1986-05-09
Abstract: The yield of active cells of Treponema hyodysenteriae is increased by cultivating such cells in a nutrient medium which contains a cholesterol-rich bovine fraction. Cells cultivated in this way and killed can be used to produce a bacterin which is active against dysentery in pigs.
Patent HU-208445-B (HU)
Inventor: BALAZS TIBOR
IPC: F16L1/028
Filed: 1991-06-17
Abstract: A berendezések tartóváza (10), hidraulikus munkahengere, valamint a sajtolandó csőre (7) és a hidraulikus munkahengerről a sajtolóerő átadására szolgáló eszköze van. A berendezésnek az a lényege, hogy a tartóváz (10) magassági értelemben állítható elülső és hátsó kerettel (42; 19), valamint ezeket összekötő oldalgerendákkal (10b) rendelkezik, amelyeken meneszthető tolókocsi helyezkedik el. Ehhez egyrészt a hidraulikus munkahenger van az egyik végével csatlakoztatva,
másrészt a sajtolandó cső (7) oldható rögzítésére szolgáló megfogószerkezettel (6) van ellátva, a hidraulikus munkahenger pedig a másik végével ugyancsak az oldalgerendákon (10b) meneszthető reteszelő szerkezethez van kapcsolva. Ez az oldalgerendákhoz (10b) egymástól távközökkel (z) kiosztott helyeken rögzíthetően és e helyekről a rögzített állapotából oldhatóan van kialakítva.
Patent HU-184868-B (HU)
Inventor: ECSER LASZLO
IPC: F16L9/14
Filed: 1981-07-21
Abstract: A találmány csőszerkezet nagynyomású korrozív közegek, mint pl. kőolaj, földgáz, zagy stb. szállítására, amely lényegében kettősfalú csőből áll, ahol a külső cső fémből van, a belső cső műanyag és a két cső között gyűrűs tér van, amely korrózióra érzéketlen, nyomásátadó közeggel van kitöltve. A találmány eljárás is, melynek lényege, hogy a megépített, vagy újonnan létesített fémcső vezetékben nagy szakaszokban műanyag csövet húzunk be. A fémcső vezetékbe, annak belső átmérőjénél kisebb külső átmérőjű szilárd falú műanyagcsövet pl. kemény polietiléncsövet húzunk be és a kettő között gyűrűs teret hagyunk. A gyűrűs teret a továbbiakban zárószerelvénnyel lezár- 5 juk, majd a két cső közötti gyűrűs teret a fémcső vonatkozásában ínért anyaggal, pl. inhibitált vízzel vagy cementtejjel, vagy egyéb nyomástátvivő közeggel töltjük fel. A találmány előnye abban van, hogy a megépített, vagy a már meglévő csővezetékek korrózióvédelme ha- 10 tásosan megoldható a lefektetett csőhálózat cseréje nélkül.  184868 -1-
Patent HU-182370-B (HU)
Title: Arrangement for resetting carrier
Inventor: FRIGYES ISTVAN
IPC: H04L27/227
Filed: 1981-08-25
Abstract: Circuit for the suppression of the carrier for the transmission of digital signals in a communication connection with a coherent demodulation and suppressed wave carriers. The circuit comprises one or a plurality of spectral indicators detecting the shifting of the spectrum of the modulated signal and regulating the variable electronic element appropriately comprised of an adjustable oscillator. The circuit is arranged in the receiver portion of the connection, the output being connected to the reference input. In order to provide for the random process of the modulating digital signal, the circuit comprises, on the transmitter side of the connection, a bit mixer, whereas on the receiver side there is provided a bit separator. In connections with suppressed carrier, the circuit comprises a locked phase loop and/or stages carrying out non-linear operations.
Patent HU-206302-B (HU)
Inventor: BRUECKNER CHRISTIANE
IPC: C07C29/32
Filed: 1989-05-19
Abstract: <p>Herstellung von E7/Z9-Alkadien-1-olen der Formel I
<chemistry id="chema01" num="0001"></chemistry> (mit R¹ = C₁-C₈-Alkyl, R² = H oder basenstabile Hydroxyl-Schutzgruppe), indem man ein ggf. an der OH-Funktion geschütztes 7-Hydroxyheptanal II<br />
OHC-(CH₂)₆-OR²      II<br />
mit einem Phosphorylid III
<chemistry id="chema02" num="0002"></chemistry> in dem<br />
R³, R⁴      eine niedermolekulare Alkylgruppe bedeuten oder miteinander zu einem gegebenenfalls C₁-C₄-alkylsubstituierten Dioxan- oder Dioxolansystem verbunden sind und<br />
R⁵      für Alkyl, Cycloalkyl oder ggf. substituiertes Phenyl steht,<br />
im Sinne einer Wittig-Reaktion umsetzt zu Verbindungen der Formel IV
<chemistry id="chema03" num="0003"></chemistry> die man unter Einwirkung von Säure in das trans-konfigurierte 2-Nonenal V
<chemistry id="chema04" num="0004"> --> überführt, das man durch eine weitere Wittig-Reaktion mit einem Phosphorylid VI<br />
R¹-<math display="inline"><mrow><mfrac linethickness="0"><mrow><mtext>5</mtext></mrow><mrow><mtext>3</mtext></mrow></mfrac></mrow></math></maths>      VI,<br />
worin R¹ und R⁵ die obengenannte Bedeutung haben, zu den E7/Z9-Alkadien­olen I umsetzt, die man in an sich bekannte Weise aus dem Reaktionsgemisch gewinnt.  </p>
Patent HU-195660-B (HU)
Title: Process for preparing sorbinyl
Inventor: CUE BERKELEY W
IPC: C07D311/68
Filed: 1985-08-22
Abstract: Chiral sorbinil intermediates of the formulawherein R is hydrogen or benzyloxycarbonyl and Y is hydroxy or amino, processes therefor, and processes forthe conversion thereof to sorbinil.
Patent HU-188711-B (HU)
Title: Herbicide compositions containing new nicotinamide derivatives and process for producing new nicotinamide derivatives
Inventor: CRAMP MICHAEL C
IPC: C07D213/80
Filed: 1981-11-20
Abstract: Nicotinamide derivatives of the formula:-
     (wherein X represents an oxygen or sulphur atom, R 1  represents a hydrogen atom or a methyl, ethyl or allyl group, R 2  represents a hydrogen, fluorine or chlorine atom, a cyano group or a methyl or ethyl group optionally substituted by one or more fluorine atoms, R 3  represents a fluorine, chlorine or bromine atom or a cyano, trifluoromethyl, methoxy, ethoxy, trifluoromethoxy or C 1-4  alkanesulphonyl group, one of R 4  and R 5  represents a hydrogen atom and the other represents a hydrogen, fluorine, chlorine or bromine atom or a cyano, trifluoromethyl, methoxy, ethoxy, trifluoromethoxy or C 1-4  alkanesulphonyl group, R 6  represents a hydrogen, fluorine or chlorine atom or a cyano or ethynyl group, R 7  represents a fluorine or chlorine atom, R 8  represents a hydrogen, fluorine, chlorine or bromine atom or a methyl or ethyl group and m represents 0, 1 or 2, with the proviso that when R 2  and R 6  each represent a hydrogen atom; m represents 0, have been found to possess useful herbicidal properties; herbicidal compositions, methods for controlling the growth of weeds and processes for the preparation of the nicotinamide derivatives are described.
Patent HU-211427-B (HU)
Title: Composition containing destructurized starch and thermoplastic destructurized-starch solid product having substantial dimensional stability
Inventor: SILBIGER JAKOB
IPC: C08L3/02
Filed: 1990-07-11
Abstract: A composition of matter capable of being formed into articles having substantial dimensional stability comprising     a) destructurized starch, and b) at least one polymer selected from the group of polysaccharides which have been chemically modified to contain added hydroxyalkyl groups and/or contain alkyl ether groups, and/or contain ester groups; said polymer being present in an amount effective to enhance the physical properties of said articles.   The composition may contain further conventional additives as well as hydrophobic substantially water-insoluble polymers.
Patent HU-203534-B (HU)
Inventor: CARR ALBERT ANTHONY
IPC: A61K/
Filed: 1988-12-16
Abstract: A találmány tárgya eljárás gyógyhatású vegyületek szintézisében intermedierként alkalmazható (I) általános képletű vegyületek és savaddíciós sóik előállítására, olymódon, hogy (Π) és (ΙΠ) képletű kiindulási vegyületekkel Friedel-Crafts-acilezést végeznek. Az (I) általános képletben Y   CO(CH3)n CH3 csoport, n-0-3, X   =CO csoport.  (I)  203534 B A leírás terjedetme: 4 oldal (1 lap ábra) -1-
Patent HU-206723-B (HU)
Title: Process for producing pyrido/2,3-b//1,5/benzoxazepin- and thiazepin/-5/6h/-ones and pharmaceutical compositions containing them
Inventor: SCHMIDT GUENTER
IPC: C07D513/04
Filed: 1990-08-28
Abstract: "Disclosed is the use of dipenz"
Patent HU-199398-B (HU)
Title: Process for producing dl-treo-1-/p-nitrophenyl/-2-amino-1,3-propanediol-hydrochloride
Inventor: BURES MAGDOLNA
IPC: C07C215/30
Filed: 1987-12-31
Abstract: DL-threo-1-(p-nitro-phenyl)-2-amino-1,3-propane-diol-hydroc hlorid- e is prepd. by a Meerwein-Porndof redn. of p-nitro-acetamido -beta-hydroxy-propio-phenone with aluminium-iso-propoxide in an iso-propyl-alcoholic medium. The redn. complex is decomposed by water. The obtd. DL-threo-1-(p-nitro -phenyl)-2-acetemido -1,3-propane-diol is hydrolised and converted to DL-threo-1-(p-nitro-phenyl)2-amino -1,3-propane-diol-hydrochloride. The reaction is carried out in one step without isolating of DL-threo-1-(nitro-phenyl) -2-amino-1,3-propane-diol.
Patent IT-1201220-B (IT)
Title: Paper roll formation
Inventor: BIAGIOTTI GUGLIELMO
IPC: D21H/
Filed: 1985-01-29
Granted: 1989-01-27
Abstract: Polyolefin film with a mat finish comprises at least two coextruded layers; an upper mat finish layer comprising high density polyethylene, polypropylene or blends thereof and a second layer comprising low density polyethylene, linear low density polyethylene or blends thereof. The film is prepd. by coextrusion of an external layer comprising high density polyethylene, polypropylene or blends thereof and an internal layer comprising low density polyethylene, linear low density polyethylene or blends thereof. The extrusion process comprises passage of the coextruded layers from feed zone to an extruder die through temp. control zones where the external layer passing through the temp. control zones from the feed zone is heated more rapidly to a higher temp. than the corresp. internal layer in the corresp. temp. control zone
Patent LV-11593-B (LV)
Title: Use of dimeticone for treating constipation
Inventor: SCHMIDT ALFRED
IPC: A61K31/80
Filed: 1996-06-28
Abstract: The invention disclosed relates to the use of dimeticone as an agent for treating constipation.
Patent LV-12400-B (LV)
Title: Method of treating pulmonary inflammation
Inventor: STURM ROBERT JOSEPH
IPC: A61K35/74
Filed: 1999-10-21
Abstract: Invention provides a pharmaceutical composition for preventing or reversing pulmonary inflammation in a mammal comprising rapamycin prepared by processes known per se and if desired a pharmaceutically acceptable carrier, diluent or excipient. Said composition being adapted for administration orally, parenterally, nasally or intrabronchially. As such, rapamycin is useful in providing the symptomatic relief of diseases in which pulmonary inflammation is a component, such as, asthma, chronic obstructive pulmonary disease, emphysema, acute respiratory distress syndrome, bronchitis and the like.
Patent MX-163742-B (MX)
Inventor: VELASCO VICENTE SANCHEZ
IPC: F16B21/16
Filed: 1986-10-30
Abstract: The invention refers to an anchoring system on concrete, on basis of threaded bolts to be installed in holes previously made on the concrete or material to be dealt with. Such improvements are centered in the existence at the internal end of the stud (1), of a trunk-conical head, immediately inside which is located, on the stud (1), an assembly of pieces (3) which determine a cylindrical bush (5), having its internal surface striated, like the external surface of the head, and with its external surface provided with a perimetral groove, on which is located an elastic ring (4) which holds such pieces (3) adapted against the neck of the stud (1). The said groove constitutes a weakening line for such pieces (3), through which, during the tightening, these are obtusely bent outwards, creating a radial and effective overdimensioning of the head, which is going to give rise to the mooring point of the bolt in the widening established at the bottom of its corresponding housing.
Patent MX-169006-B (MX)
Inventor: MUDGE PAUL R
IPC: C09J7/02
Filed: 1986-12-05
Abstract: Permanently tacky pressure sensitive adhesives comprise terpolymers consisting essentially of 35-50% by weight of a vinyl ester of an alkanoic acid, 15-30% by weight ethylene and 35-50% by weight of di-2-ethylhexyl maleate or di-n-octyl maleate or di-n-octyl maleate or a corresponding fumerate.
Patent NO-135049-B (NO)
Inventor: MORIO M
IPC: H04N11/16
Filed: 1971-12-03
Abstract: Dekodingsanordning for en fargefjernsynsmottaker.
Patent NO-140787-B (NO)
Title: Aerosol-inhaleringsanordning.
Inventor: WETTERLIN KJELL INGVAR LEOPOLD
IPC: A61M11/02
Filed: 1976-12-06
Abstract: Aerosol-inhaleringsanordning.
Patent NO-148831-B (NO)
Inventor: JUGUE BERNARD MARIE
IPC: F41F1/06
Filed: 1981-03-25
Abstract: 1. Quick-firing mortar containing firstly a barrel (4) mobile whilst firing in relation to a support (1) and secondly an ammunition cylinder (7) integral translation-wise with the barrel, and containing at least two chambers (8, 10) that can be placed one in firing position (X) and the other in loading position (Z), characterized in that the chambers have means (11a, 11b, 11c) of ensuring their fixity in relation to the support when firing, when placed in at least one position other than firing position.
Patent NO-159758-B (NO)
Title: Anordning for kopling av en elektrisk stikkontakt.
Inventor: DECKERS WILLY
IPC: H01R43/01
Filed: 1983-09-19
Abstract: Anordning innbefattende en hovedsakelig fast ramme (10) med en stikkontaktholder (14) og to motsatt anordnede innføringsenheter forsynt med innføringsstanser (31) og som kan bli forskjøvet langs stikkontaktholderen (14) ved hjelp av en vogn (20), idet hver ende av innføringsenheten er forsynt med ledningsføringsinnretninger ved hvilke i det minste den ene ledningsføringsinnretningen er bevegelig anordnet for således å tilveiebringe en passasje eller et gap mellom føringsinnretningen som kan være tilpasset ledningens stør-relse eller art som skal bli ført inn i stikkontakten.
Patent NO-173665-B (NO)
Inventor: GREISER WOLFGANG
IPC: D04H1/46
Filed: 1985-09-27
Abstract: A multilayered fabric which when used as support material for built-up roofing and sealing membranes shows not only good fire properties but also improved mechanical properties is obtained by needling together two preconsolidated fibre webs, one of which consists of synthetic fibres and the other of mineral fibres. The needling produces a strong positive bond between the two webs, which prevents the parting of the two layers under extreme thermomechanical conditions.
Patent NO-175064-B (NO)
Inventor: SAVINO THOMAS G
IPC: C09D175/00
Filed: 1988-08-10
Abstract: This invention, therefore, relates to the field of polyurethane coatings for use in automobile basecoat/clearcoat systems. In particular, this invention relates to water-dispersible polyurethane resins having polyether sidechains which may be utilized in basecoat compositions as principal resins or grind resins. These polyurethane resins may be laterally stabilized or terminally stabilized. The terminally stabilized resins of this invention are preferably employed as principal resins in basecoat compositions.
Patent NO-176896-B (NO)
Title: Rörformet måleblende for apparat til isokinetisk prövetaking av fluid
Inventor: DYBDAHL BJOERN
IPC: G01N1/20
Filed: 1992-12-28
Abstract: En rørformet måleblende (10) for apparat til isokinetisk prøvetaking av fluid. Det er tatt sikte på å unngå dannelse av turbulens og trykkvariasjoner i området for måleblendens innløpshull (13) i forbindelse med prøvetaking av strømmende fluid. For dette formål har måleblenderøret (10) et awinklet fritt endeparti (10b) hvori innløpshullet (13) er utformet, hvilket awinklede frie endeparti (10b) er tilspisset mot den frie innløpshullmunningskant (10c) som har minimal tykkelse. Måleblenderøret (10) som har et rett tilkoplingsparti (10a), kan derved ha et ytterligere awinklet rørparti (10d) mellom tilkoplingspartiet (10a) og det av-• vinklede, frie endeparti (10b) , idet det awinklede frie endeparti (10b) av måleblenderøret (10) danner en vinkel på ca. 90° med nevnte tilkoplingsparti (10a) og en spiss vinkel med'nevnte andre awinklede rørparti (10d) .
Patent SE-329255-B (SE)
Inventor: AUTIO T
IPC: C08F2/46
Filed: 1968-02-21
Abstract: The present invention relates to a method for preparing plastic impregnated wood, in which dry wood (moisture content below 10 percent) is impregnated with liquid resin material in a manner prior known per se e.g. the wood is put into a vacuum impregnation vessel, the air is evacuated, the vessel flushed with nitrogen, the liquid resin is introduced in the vessel until the wood is immersed, an atmospheric nitrogen pressure or an overpressure of 1 to 8 atmospheres gauge is applied. The wood is transferred into bags or containers filled with nitrogen, then hermetically sealed, then the impregnated wood is cured utilizing radioactive radiation optionally in the presence of chemical catalyst addition. The resin utilized for the wood impregnation contains commercial unsaturated polyester between 35 and 95 percent and styrene and/or methyl methacrylate. The amount of radiation is between 0.5 and 1.5 Mrad in the case of gamma radiation and between 1 and 5 Mrad if high energy electron radiation is used. As chemical catalyst is used an organic peroxide and the curing is carried out at a temperature between 40 DEG  and 60 DEG  C. utilizing as additives when necessary chemical inhibitors such as pinene in an amount of less than 5 percent.
Patent SE-339260-B (SE)
Inventor: KOPPELMANN F
IPC: H02M7/527
Filed: 1965-03-09
Abstract: 1,103,753. Inverting. LICENTIA PATENTVERWALTUNGS G.m.b.H. 12 March, 1965 [13 March, 1964], No. 10586/65. Heading H2F. The output current of a driven inverter, which may supply a motor, is regulated by comparison with a reference level which varies during each half-cycle of the output.
Patent YU-45517-B (YU)
Title: Filter for separating particles of solid substance from hot gasses as well as liquids
Inventor: HERDING W
IPC: B01D29/52
Filed: 1989-06-02
Abstract: The invention relates to a filter for separating solid particles from hot, gaseous or liquid media, which comprises a heat-resistant carrier material having a large pore width and a likewise heat- resistant material of smaller pore width as a covering layer for the carrier material. 
<??>While the carrier material can, for example, consist of ceramics, the covering layer is formed by a multiplicity of grains of a material similar or related to the carrier material, so that a bond of identical or approximately identical materials or a eutectic of miscible materials can be formed between the covering layer and carrier material during a subsequent heating step. 
<IMAGE>
Patent YU-46425-B (YU)
Inventor: EGGLER J F
IPC: C07D277/34
Filed: 1987-07-14
Abstract: POSTUPAK ZA DOBIJANJE HIPOGLIKEMIJSKIH TIAZOLIDINDIONA, formule (I): ili njegove farmaceutski prihvatljive katjonske soli, u kojoj je n nula, 1 ili 2, X je 0, -S, -SO uku -SO2, R je H, kada se uzme pojedina; no R2, R3 i R4 su vodonik, R1 je (C1-C6) alkil, (C5- C7)cikloalkil, (C5-C7) cikloalkil/metil, benzil, fenil, benzil ili fenil supstituisani na aromatičnom prstenu sa CH3, CH3O, OH ili F, kada su R1 i R2 vodonik, R3 i R4 uzeti zajedno obrazuju (C4-C6) alkilen, kada su R3 i R4 vodonik, R1 i R2 uzeti zajedno obrazuju (C4-C6) alkilen, u kome ekvimolarne količine jedinjenja formula (IV) i (VI); u kojoj su n, R, R1-R4 i X kao što je gore definisano, reaguju u prisustvu slabe baze, kao što je natrijum acetat, na tempeaturi u opsegu od 100 do 250 stepeni C, najpoželjnjije na temperaturi od 140 stepeni C, tako da se dobija jedinjenje formule (III): u kojoj su n, R, R1-R4 i X kao što je prethodno definisano i što se tako dobijeno jedinjenje formule (III) redukuje u reakciono intertnom rastvaraču, kao što je glacijalno sirĆetna kiselina, u prisustvu sredstva za redukciju kao što je vodonik i katalizatora na bazi plemenitog metala, kao što je paladiju, na temperaturi od 0 do 60 stepeni C, najpogodnije od 25 do 50 stepeni C i što se, kada se želi dobiti jedinjenje formule (II), gde X predstavlja - SO- ili -SO2-, vrši oksidacija jedinjenja formule (II), gde X predstavlja -S-, sa vodonik-peroksidom u rastvaraču kao što je sirĆetna kiselina, prema osnovnom patentu br. 44573, naznačen time, što X u formulama (I) i (III) i (IV) predstavlja -CH2-,-C=O, -CHOH- ili NR5 ili gde R5-, gde R5 predstavlja H, formil grupu, (C2-C5) alkanoil, benziloksikarbonil, CO(CH2)xC6H5 gde x predstavlja ceo broj od 1 do 3, ili (C1-C6) alkil koji je proizvoljno supstituisan sa OH, Cl, Br, OCH3 ili fenil grupa.
Patent ZA-795147-B (ZA)
Title: N-diazolylalkyl-halogenoacetanilides,process for their preparation and their use as herbicides
Inventor: DITGENS K
IPC: C07D285/08
Filed: 1979-09-27
Abstract: Novel N-Diazolylalkyl-haloacetanilides of the formula    <IMAGE>  (I) wherein A is oxygen, sulphur or the grouping <NR,  wherein R is hydrogen or alkyl, R1 is hydrogen, alkyl or alkoxy, R2 is hydrogen, alkyl, alkoxy or halogen, R3 is hydrogen, alkyl, alkoxy or halogen, R4 is hydrogen or alkyl, X is hydrogen, alkyl, halogen, alkoxy, alkylthio, haloalkyl, alkenyl, alkynyl, alkoxycarbonyl, dialkylamino, cyano, phenyl, substituted phenyl, phenoxy, substituted phenoxy, phenylthio or substituted phenylthio, and Z is halogen, and in which the diazolyl radical is bonded via a carbon atom, and acid addition salts and metal salt complexes thereof.
Patent ZA-825493-B (ZA)
Title: Mounting clasp
Inventor: KRAUSER MICHAEL
IPC: B62J9/00
Filed: 1982-07-30
Abstract: 1. Retaining tongue, for the fastening and securing of a motor cycle bag at a retaining frame attached laterally at a motor cycle, with a cut-out, characterised thereby, that in the prolonged tongue (10) at its free end (12) projecting from the retaining frame, a second equally large cut-out (5) is still formed in front of the cut-out (2), wherein both the cut-outs (2, 5) are each separated from the other by a narrow weg (7).
Patent ZA-843826-B (ZA)
Title: Deodorisation process for triglyceride oil
Inventor: MERK WERNER
IPC: C11B1/14
Filed: 1984-05-21
Abstract: Process and apparatus for deodorising triglyceride oil comprises passing dry steam through the oil, the oil being at a temperature between 160 and 280 DEG C and under a pressure of between 0.1 to 8.0 mbar and condensing by indirect condenser means a vapour phase having a Reynolds number less than 2300 and comprising steam, volatile materials from the oil and less than 100 mg neutral oil per m<3> of steam when measured under the conditions prevailing in the headspace above the oil. The condensate can be solid or liquid form. In either case the condensate can be readily drained from the condenser.
Patent ZA-863230-B (ZA)
Title: Symmetrical fault current detector
Inventor: AUBREY DAVID RICHARD
IPC: H02H3/08
Filed: 1986-04-30
Abstract: @ Excess currents due to faults in an electrical power system are generally larger than excess currents due to the magnetisation of distribution transformers: discrimination has hitherto relied on a threshold detector. Magnetising currents are however, asymmetrical whereas fault currents are symmetrical. This specification discloses a detector which can detect symmetrical current waveforms on a conductor 1 and thus discriminate between a fault and a magnetising excess current. A resistor 4, placed across the output terminals of a bridge rectifier 3 has a resistance selected so that the voltage across it exceeds the breakdown voltage of trigger diodes 7 and 8 when the current in conductor 1, in any half cycle, exceeds a desired maximum. Capacitors 13 and 14 will thus only both charge up in response to a large symmetrical current: a logic control 23 is connected via lines 21 and 22 to detect such a condition.