US3668577A - Leakage circuit breakers - Google Patents

Leakage circuit breakers Download PDF

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Publication number
US3668577A
US3668577A US98875A US3668577DA US3668577A US 3668577 A US3668577 A US 3668577A US 98875 A US98875 A US 98875A US 3668577D A US3668577D A US 3668577DA US 3668577 A US3668577 A US 3668577A
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United States
Prior art keywords
armature
arrangement
magnetic
magnet
support structure
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Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
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US98875A
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English (en)
Inventor
Horst Harings
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Felten & Guilleaume Schaltanl
Felten & Guilleaume Schaltanlagen GmbH
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Felten & Guilleaume Schaltanl
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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H71/00—Details of the protective switches or relays covered by groups H01H73/00 - H01H83/00
    • H01H71/10—Operating or release mechanisms
    • H01H71/12—Automatic release mechanisms with or without manual release
    • H01H71/24—Electromagnetic mechanisms
    • H01H71/32—Electromagnetic mechanisms having permanently magnetised part
    • H01H71/321—Electromagnetic mechanisms having permanently magnetised part characterised by the magnetic circuit or active magnetic elements
    • H01H71/323—Electromagnetic mechanisms having permanently magnetised part characterised by the magnetic circuit or active magnetic elements with rotatable armature

Definitions

  • Movement of the armature is coupled to the tri ing PP Jan 2 1970 German P 20 0O 38 I catch that operates the circuit breaker by a lever connected by y an axle to the armature.
  • One spring biases the armature open [52] U s 335/192 335/229 and closed when the latter is respectively closed and open. 51 ln t. Cl. ..H 0lh 3/32 Sprig biases armature
  • the invention relates to a magnetic tripper for an earth leakage circuit breaker.
  • Earth leakage circuit breakers are used to protect life and property in power plants, during unusual occurrences, such as ground leaks or the touching of a live part.
  • the operation and construction are described, for example, in Giinter G. Seip's article Stammer Uberblick iiber die proceedings fil'r das Eronne von Starkstromanlagen mit Nennschreiben bis 1,000 V, VDE 0100/1265 (General Survey of the. Requirements for Constructing Power Plants Having Nominal Voltages of Up to 1,000 Volts, VDE 0100/1265), printed in the German journal VDI-Zeitung 111 (1969), issue No. 15, pages 1,081-1087.
  • the effectiveness of the circuit breaker is largely determined by a magnetic tripper that is used in conjunction with the breaker.
  • the magnetic tripper has a magnetic circuit of which a winding is connected to the secondary circuit of the totalizing current transformer, a determined fault current causing the tripper to release the breaker, which opens.
  • the tripper should be as sensitive as possible, so that it releases the breaker at small fault currents. Since the circuit breakers are robust units that should be mountable anywhere in the power plant, the magnetic tripper must be vibration and shock proof as possible.
  • the two pole pieces are stamped out of the same base, each pole piece carrying a coil of insulated wire, which is connected to the secondary winding of the totalizing current transformer of the earth leakage circuit breaker.
  • a permanent magnet is located on the base between the two pole pieces. This part of the piece acts as a magnetic shunt to the main magnetic circuit closed by these pole pieces. By suitably dimensioning the magnetically effective cross-section of this shunt, the flux caused by the permanent magnet can be so adjusted that it is sufficiently large to ensure a satisfactory attractive force to hold the armature against the pole pieces and yet sufficiently small to obtain a satisfactory sensitivity.
  • a magnetic tripper of thiskind is described in the French Patent of Addition 78880 and in the parent thereof 1265883.
  • the French Pat. 1242875 describes a similar magnetic tripper, the north-south axis of the permanent magnet being rotatable with respect to the axis of the main magnetic circuit so as to enable further adjustment of the sensitivity of the tripper.
  • German Patent 1 197695 describes a concentric arrangement having a single trip coil and a plunger type magnet. Even in this arrangement the armature has a relatively large mass, because the entire armature must be moved. Moreover, the sensitivity is reduced by an unavoidably large amount of friction, which the armature must overcome when moving in its concentric air gap.
  • An object of the invention is a magnetic tripper for earth leakage circuit breakers that better fulfills the requirements of high sensitivity to fault currents and low sensitivity to vibration and shock than do the magnetic trippers of the prior art.
  • Another object of the invention is a magnetic tripper of the previous object, whose sensitivity to fault currents can be coarsely and finely adjusted.
  • the magnetic tripper of the invention consists essentially of a magnetic circuit including first and second spaced pole pieces and an armature movable between a first position in which the circuit breaker is closed and a second position in which the circuit breaker is open, the position of the armature determining whether the magnetic circuit is open or closed, a trip coil wound on the first pole piece, resilient means for biasing the armature towards the second position at least when the armature is in the first position and towards the first position at least when the armature is in the second position, the resistance of the magnetic circuit, size of wire and turns of the trip coil, and the force of the resilient means coarsely determining the size of the fault current at which the armature moves from the first to the second position, a permanent magnet mounted on the second pole piece free to move so as to change the direction of the north-south pole axis of the magnet with respect to the second pole piece and thereby vary the amount of magnetic flux, due to the magnet, in the magnetic circuit, the position of the permanent magnet finely determining the size of the
  • FIG. 1 is a top view of the magnetic tripper of the invention, with the armature closed;
  • FIG. 2 is a side view of the tripper, with the armature closed;
  • FIG. 3 is a side view showing part of the tripper, with the armature open;
  • FIG. 4 is an end view of the tripper
  • FIG. 5 is a perspective view of the tripper
  • FIG. 6 is an exploded view of the magnetic circuit of the tripper.
  • the reference numeral 1 denotes the base or support structure of the magnetic tripper.
  • the base 1 comprises rail-like extensions that each carry respective electrically insulating mounting members 19 and 20, which latter will be referred to later.
  • the base can consist of a U-shaped piece, which, by injection molding, is embedded in a housing, not shown, preferably made of a thermoplastic material.
  • the base 1 is made of soft iron having a high permeability and low retentivity and coercive force.
  • the two pole pieces 2 and 3 are stamped out of the base 1.
  • a permanent magnet 5 is mounted free to rotate in a hole, not shown, incorporated in the rear pole piece 3.
  • a lever 6 of nonmagnetic material is fixed to the permanent magnet.
  • the permanent magnet 5 is made of a material having high coercive force and retentivity, the material preferably being sintered.
  • the magnet is so magnetized that its north and south poles define a diametrical axis that is coincident with, or an extension of, the longitudinal axis of the lever 6.
  • the magnetic circuit is closed by an armature 7, which is also made of an easily magnetized material. When the armature 7 is in its first, at-
  • the tracted, position, the front, or left, end 8 of the armature has a contact surface which is in contact with the opposed abutment face of the pole piece 2.
  • the rear, broad, end of the armature 7 incorporates an opening 9.
  • the entire armature is bowed along a line A-A (see FIG. 6), this line being coincident with the front lower edge of the opening 9.
  • the edge formed along the line A-A contacts the pole piece 3 along the line B--B. Since the opening 9 is wider than the pole piece 3, the armature is free to pivot on this line in the manner of a balance.
  • the plate spring 10 is fixed to the underside of the rear end of the armature.
  • the other end of the plate spring is fixed to the trip coil 4. In this way, the armature is fixed against lateral movement with respect to the pivot line AA.
  • Two V-shaped recesses define between the apices a bridge 1 1 over which is caught one end of a tension coil ring 12.
  • the other end of the coil spring 12 is fixed to a cross tie 13, which is mounted on the rear end of the base 1.
  • the coil spring 12 pulls'on the armature to pivot the latter and to break the magnetic circuit at the pole piece 2.
  • the position at which the spring 12 is hooked to the bridge 11 is advantageously a determined distance higher than the pivot line AA.
  • the position at which the spring is hooked to the bridge describes an arc.
  • the lever arm through which the spring 12 acts is the horizontal projection of this arc.
  • the reduced tension of the spring as the latter contracts can be compensated, or overcompensated, by so choosing the hooked position of the upper end of the spring 12, in the first position of the armature, that the equivalent lever arm through which the spring acts increases as the armature pivots to the second position.
  • the position of the upper end of the spring 12, in the first position of the armature 7, is thus made somewhat above that of the line AA; in other words, the position of the upper end of the spring is angularly displaced in a plane normal to the line AA.
  • the armature 7 incorporates a slot 14, which is covered with non-magnetic material and is approximately centered between the ends of the armature.
  • a trip lever 15 is free to move with play in this slot.
  • An axle that bridges this slot is fixed to the underside of the armature. The axle passes freely through an opening in the tripping lever, so that the latter is moved whenever the armature pivots.
  • An opening 17 in the base 1 so guides the movement of the tripping lever 15 that the trip catch 18, located at the lower end of the lever 15, moves in a direction substantially parallel to the longitudinal axis of the lever 15.
  • the front and rear rails of the base I carry electrically insulating mounting members 19 and 20, each incorporating respective holes 21 and 22 for fixing the magnetic tripper to the circuit breaker.
  • the plate spring l0 in the position of the armature 7 shown in FIG. 2, reinforces the pull of the spring 12. In the armature position shown in FIG. 3, it opposes the pull of the spring 12 and acts to urge the armature towards its closed position, shown in FIG. 2.
  • the force acting to hold it there is multiplied by the ratio between a first lever arm and a third lever arm, the first lever being that arm extending from the left end 8 of the armature to the line A- A, the third lever arm, which is necessarily shorter than the first, being from the axle 16 to the line AA.
  • the restoring force of the plate spring 10 is multiplied by the ratio between a'second lever arm and said third lever arm, the second lever, which is necessarily longer than said third, being that arm extending from the right end of the armature, as seen in FIG. 3, to the line AA.
  • the permanent magnet 5 has a coercive force l-I. If the efiective length of the magnet is 1 and if its north-south axis makes an angle (b with the vertical, it has, in the direction of the axis of the pole piece 3, an effective internal magnetic circulation@, H cos (I) 1. This magnetic circulation has the same effect as though the magnet were replaced by a corresponding soft iron body that carried a coil through which there flowed a current producing the same magnetic circulation.
  • the lever 6 is so attached to the magnet 5 that when the lever is in'its end position, the north-south axis of the magnet coincides with the vertical axis of the pole piece 3. When the lever 6 is moved, the angle 4) is chan ed, and thereby the effective internal magnetic circulation -of thepermanent magnet is varied. The effect is exactly the same as though the magnitude of the current flowing through the imaginary coil were changed.
  • the pole piece 2 carries the coil 4, which is connected to the secondary winding of the totalizing current transformer of the earth leakage circuit breaker.
  • the fault current flows through the coil 4.
  • the two magnetic circulations VI and 2 cause in the entire magnetic circuit a flux I the magnitude of which depends on the magnetic resistances (1 .q) of the different parts of the n ti s w t hsrs ssya sths sn l w Permeability,
  • This flux I corresponds to the force with which the armature 7 is held in its first position, shown in FIG. 2. At some defined strength and direction of the current in the coil 4 this attractive force is so weakened that the plate spring 10 and the coil spring 12 cause the armature to pivot upward and thereby to raise the tripping lever 15. The tripping catch 18 consequently disengages the circuit breaker, which latter opens the circuit.
  • the value of the current through the coil 4 at which the magnetic tripper acts is coarsely dependent on the shape and cross-section of the magnetic circuit composed of the base 1, pole pieces 2 and 3, support surface A-A, and the contact between 8 and the pole piece 2 as well as on the force of the springs 10 and 12.
  • the sensitivity of the magnetic trigger is finely determined by moving the lever 6 to turn the permanent magnet 5.
  • the attractive force between 8 and 2 acts through such a leverage against the opposed force of the springs 10 and 12 that it can be relatively small. It is consequently possible to obtain the required magnetic circulation for the necessary flux with a single coil 4 and a correspondingly small permanent magnet 5. Another consequence is to render the magnetic tripper more vibration insensitive. This latter feature is also made possible by the very secure manner in which the broad, rear, part of the plate spring 10 holds the armature 7. Since the permanent magnet 5 is made from sintered material having a particularly high coercive force and retentivity it is not weakened by the frequent release of the magnet tripper, caused by the opposing force produced by the fault currents. The sensitivity of the tripper is further improved by the following constructive details of the armature 7.
  • the armature is designed so that the mass of that part of the armature to one side of the line A-A is as nearly equal as possible to that on the other side of the line A-A. This means that the weight of the forepart of the armature, which is attracted to the pole piece 2, is balanced by the weight of the rear part of the armature. Consequently, the amount of attractive force required to act on the part 8 is reduced.
  • the armature front end 8 By keeping the armature front end 8 very small, it is possible to ensure that it lies plane parallel on the face of the pole piece 2.
  • the so-called end mass effect acts to keep the end 8 in contact with the pole piece 2 even when the tripper is vibrated.
  • the forepart of the armature which is that part most accelerated when the armature moves from its one position to the other, has a very small inertia.
  • the design of the armature also ensures that the air resistance is kept very low during movement of the armature.
  • the magnetic resistance in the rear part of the armature is kept very low, because the armature contacts the pole piece 3 for a major part of the long line A-A.
  • the resulting magnetic flux which is the resultant of the magnetic circulation caused by the permanent magnet 5 and the magnetic circulation caused by the fault current in the trip coil 4, is inversely proportional to the resistance of the magnetic circuit.
  • the surface area of the armature in contact with the pole piece 3 is large compared to the surface area of 8 in contact with the pole piece 2.
  • the force acting on the armature is dependent on the mag nitude of this resultant magnetic flux; and, of course, it is also inversely proportional to the resistance of the magnetic circuit.
  • the magnetic resistance is greatly dependent on the precision with which the contact surfaces between 8 and 2, on the one hand, andbetween 3 and 7, on the other, are machined and finished. The smaller is the contribution of these contact surfaces to the total resistance of the magnetic circuit, the less is the effect of the unavoidable variations in the contribution, caused by the limitations of machining and finishing, on the attractive force between 8 and 2.
  • armature 7 is coupled to the tripping catch 18 by a two-arm step-up lever arrangement that multiplies the force of the springs 10 and 12 that cause the armature to pivot upwards when the magnetically attractive force becomes too weak.
  • a one-arm step-up lever arrangement holds the armature to the pole piece 2.
  • a further advantage of the invention is that the leverage through which the attractive force and the holding force (of the forepart of the armature) act on the tripping catch 18 enables the forepart, which undergoes the greatest acceleration when the armature moves, to be made with so little mass that it is insensitive to vibration.
  • the lever arrangement as previously explained, nevertheless ensures that the tripper releases with sufficient force to operate the catch 18.
  • the weight of the forepart of the armature 7 is balanced, or at least very nearly balanced, by the weight of the rear part, a
  • the contact face of the end 8 is small to ensure that it lies plane parallel on the opposed face of the pole piece 2, thereby obtaining the maximum attractive force between 8 and 2 for a given flux.
  • the shock proof, or vibration proof, characteristics of the tripper imply that the armature, once attracted to the position shown in FIG. 2, must be securely held. When two plane steel surfaces are pressed together, the air between them is largely squeezed out, and the pressure between the surfaces is less than the atmospheric. Assuming that there is a perfect vacuum between these two surfaces, this holding force, aside from the resultant holding force of the magnetic attraction and the opposing force of the springs 10 and I2, is equal to the product of the contact area and the atmospheric pressure.
  • the holding force due to the end mass effect should not be too great, since the opposed force of the springs 10 and 12 must be correspondingly increased.
  • the sensitivity is increased by keeping the contact area between 2 and 8 small. In this wise, there is obtained, in accordance with the invention, both very high sensitivity and great resistance to shock and vibration.
  • the base 1 can be contained in a housing, not shown, preferably injection molded of thermoplastic material, the pole pieces 2 and 3 being embedded in the housing.
  • Magnetic tripper arrangement for a circuit breaker comprising, in combination, a support structure; an elongated armature at least partly of ferromagnetic material having opposite end portions and mounted on said support structure on a pivot axis spaced from said opposite end portions so as to form between said pivot axis and said opposite end portions first and second lever arms, said armature being tiltable about said pivot axis between two tilting positions; magnetic means cooperating with one of said portions of said armature and tending when actuated to move the same and thereby tilt the armature from one to the other of said tilted positions thereof; spring means cooperating with the other of said end portions of said armature and tending to move the same from said other to said one position thereof when said magnet means is not actuated; and trip means engaged by said armature at a point between one of said end portions and said pivot axis of said armature so that the portion of said armature located between said trip means and said pivot axis forms a third lever arm shorter than either of said first or
  • said support structure including a first and a second pole piece, said armature being mounted on said second pole piece, said armature and said pole pieces forming part of a magnetic circuit which is opened or closed depending on the position of said armature, and said magnetic means producing flux through said magnetic circuit.
  • said magnetic means including at least a first magnet and a second magnet, said first magnet being a trip coil electromagnet.
  • said second magnet producing flux through said magnetic circuit in one direction, whereby to exert on said armature a force tending to maintain it in its position closing said magnetic circuit
  • said first magnet producing flux through said magnetic circuit in opposite direction, whereby to counteract the flux of said second magnet the force of said second magnet tending to maintain said armature in its position closing said magnetic circuit.
  • said second magnet is a permanent magnet movably mounted on said support structure, whereby to permit adjustable varying of the force exerted by said permanent magnet for tilting said armature to said other of its positions by moving said permanent magnet.
  • said second pole piece having along said pivot axis a width which is at least substantially equal to the width of said first pole piece along said pivot axis of said armature.
  • said spring means is a compound spring means and includes an expansion spring connected to said support structure and one of said end portions, and a plate spring connected to said support structure and to said armature, said plate spring cooperating with said expansion spring when said armature is in one of its positions and opposing said expansion spring when the armature is in the other of its positions effect of the compound spring means will be to provide a non-linear spring characteristic.
  • said latter armature portion including at least one mass-reducing cut-out.
  • said support structure includes guide means
  • said trip means comprises an elongated member having one end pivotably coupled with said armature, said member cooperating with said guide means to be guided by the same when said armature is tilted between its positions.
  • trip coil electromagnet being connected to the secondary winding of a circuit breaker totalizing transformer.
  • said support structure comprises a one-piece U-shaped body, the legs of said U including said first and second pole pieces, and said one of said armature end portions being in contact with said first pole piece when said armature is in one of its positions.

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  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Breakers (AREA)
  • Electromagnets (AREA)
US98875A 1970-01-02 1970-12-29 Leakage circuit breakers Expired - Lifetime US3668577A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE19702000138 DE2000138B2 (de) 1970-01-02 1970-01-02 Ausloeser fuer fehlerstrom schutzschalter

Publications (1)

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US3668577A true US3668577A (en) 1972-06-06

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ID=5758997

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Application Number Title Priority Date Filing Date
US98875A Expired - Lifetime US3668577A (en) 1970-01-02 1970-12-29 Leakage circuit breakers

Country Status (13)

Country Link
US (1) US3668577A (enrdf_load_stackoverflow)
JP (1) JPS5137433B1 (enrdf_load_stackoverflow)
AT (1) AT314645B (enrdf_load_stackoverflow)
BE (1) BE759996A (enrdf_load_stackoverflow)
CA (1) CA925550A (enrdf_load_stackoverflow)
CH (1) CH528815A (enrdf_load_stackoverflow)
DE (1) DE2000138B2 (enrdf_load_stackoverflow)
ES (1) ES383950A1 (enrdf_load_stackoverflow)
FR (1) FR2075891B1 (enrdf_load_stackoverflow)
GB (1) GB1295150A (enrdf_load_stackoverflow)
LU (1) LU61823A1 (enrdf_load_stackoverflow)
NL (1) NL156536B (enrdf_load_stackoverflow)
ZA (1) ZA708651B (enrdf_load_stackoverflow)

Families Citing this family (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2529221C2 (de) * 1975-07-01 1983-12-15 Schupa-Elektro-GmbH + Co KG, 5885 Schalksmühle Hochempfindlicher, permanentmagnetischer Auslöser für Fehlerstromschutzschalter u.dgl.
EP0002748A1 (de) * 1977-12-23 1979-07-11 CMC Carl Maier + Cie AG Magnetauslöser für Fehlerstromschutzschalter
JPS58119577U (ja) * 1982-02-04 1983-08-15 大日本印刷株式会社 収納箱
DE3643510A1 (de) * 1986-12-19 1988-06-30 Felten & Guilleaume Energie Magnetsystem fuer schnellabschaltung
DE3838444A1 (de) * 1988-11-12 1990-05-17 Felten & Guilleaume Energie Magnetsystem fuer schnellabschaltung
DE4111092A1 (de) * 1991-04-07 1992-10-08 Schiele Gmbh & Co Kg Fehlerstromrelais
NL1004438C2 (nl) * 1996-11-05 1998-05-08 Holec Holland Nv Stuurinrichting voor een elektrische schakelaar en een werkwijze voor het vervaardigen daarvan.
FR2877137B1 (fr) * 2004-10-21 2006-12-22 Schneider Electric Ind Sas Declencheur electromagnetique et appareil de protection electrique le comportant

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2914632A (en) * 1958-11-14 1959-11-24 Frank Scoby Relay
US3123742A (en) * 1959-06-08 1964-03-03 Moser
US3543203A (en) * 1967-08-11 1970-11-24 L Ind Electr De La Seine Electro-magnetic ultra-sensitive tripping devices

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR1288165A (fr) * 1961-02-08 1962-03-24 Comp Generale Electricite Perfectionnements aux relais électromagnétiques rapides
FR1427462A (fr) * 1964-03-20 1966-02-04 Schrack Elek Zitats Ag E Déclencheur magnétique pour disjoncteurs de protection

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2914632A (en) * 1958-11-14 1959-11-24 Frank Scoby Relay
US3123742A (en) * 1959-06-08 1964-03-03 Moser
US3543203A (en) * 1967-08-11 1970-11-24 L Ind Electr De La Seine Electro-magnetic ultra-sensitive tripping devices

Also Published As

Publication number Publication date
CA925550A (en) 1973-05-01
NL7018552A (enrdf_load_stackoverflow) 1971-07-06
BE759996A (fr) 1971-05-17
FR2075891B1 (enrdf_load_stackoverflow) 1974-12-06
FR2075891A1 (enrdf_load_stackoverflow) 1971-10-15
LU61823A1 (enrdf_load_stackoverflow) 1971-04-29
DE2000138A1 (de) 1971-07-15
ES383950A1 (es) 1973-05-01
ZA708651B (en) 1971-10-27
GB1295150A (enrdf_load_stackoverflow) 1972-11-01
JPS5137433B1 (enrdf_load_stackoverflow) 1976-10-15
AT314645B (de) 1974-04-10
CH528815A (de) 1972-09-30
DE2000138B2 (de) 1972-03-23
NL156536B (nl) 1978-04-17

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