US3763450A - Electric holding magnet serving as tripping device for ground leakage circuit breakers - Google Patents

Electric holding magnet serving as tripping device for ground leakage circuit breakers Download PDF

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Publication number
US3763450A
US3763450A US00198796A US3763450DA US3763450A US 3763450 A US3763450 A US 3763450A US 00198796 A US00198796 A US 00198796A US 3763450D A US3763450D A US 3763450DA US 3763450 A US3763450 A US 3763450A
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US
United States
Prior art keywords
legs
permanent magnet
plates
magnetic
holding magnet
Prior art date
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
Application number
US00198796A
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English (en)
Inventor
P Flohr
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.)
Siemens AG
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Siemens AG
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Filing date
Publication date
Priority claimed from DE19702056627 external-priority patent/DE2056627C3/de
Application filed by Siemens AG filed Critical Siemens AG
Application granted granted Critical
Publication of US3763450A publication Critical patent/US3763450A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F7/00—Magnets
    • H01F7/06—Electromagnets; Actuators including electromagnets
    • H01F7/08—Electromagnets; Actuators including electromagnets with armatures
    • H01F7/16—Rectilinearly-movable armatures
    • H01F7/1638—Armatures not entering the winding
    • H01F7/1646—Armatures or stationary parts of magnetic circuit having permanent magnet
    • 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
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F7/00—Magnets
    • H01F7/06—Electromagnets; Actuators including electromagnets
    • H01F7/08—Electromagnets; Actuators including electromagnets with armatures
    • H01F7/121—Guiding or setting position of armatures, e.g. retaining armatures in their end position
    • H01F7/122—Guiding or setting position of armatures, e.g. retaining armatures in their end position by permanent magnets

Definitions

  • ABSTRACT The two legs of a holding magnet for ground leakage circuit breakers are arranged in juxtaposition and form a magnetic shunt.
  • a permanent magnet at one end of the legs and the legs at such end are disposed between two pole pieces.
  • Each of the pole pieces contacts a corresponding one of the legs and a corresponding pole face of the permanent magnet.
  • Both pole pieces comprise a magnetic material having a higher magnetic saturation than the material of the legs.
  • the invention relates to an electric holding magnet. More particularly, the invention relates to an electric holding magnet serving as a tripping device for ground leakage circuit breakers.
  • the electric holding magnet of the invention serving as a tripping device for ground leakage circuit breakers, has two legs comprising material of high magnetic conductivity in juxtaposition.
  • An excitation winding is mounted on one end of at least one of the legs.
  • a permanent magnet is positioned at the other end of the legs.
  • a magnetic shunt is formed of portions of the legs in close mutual proximity and extends between the permanent magnet and the excitation winding.
  • a holding magnet of the aforedescribed type is disclosed in German Published Patent Application No. 1,665,851.
  • the permanent magnet is positioned in opposing recesses of the legs.
  • the legs comprise material of high magnetic conductivity.
  • the holding magnet has the advantage that the magnetic shunt provides it with increased trigger sensitivity. Furthermore, its geometric dimensions are reduced, because the magnetic shunt formed by the closely adjacent portions of the legs has only a single air gap.
  • An object of the invention is to provide an electric holding magnet having reduced geometric dimensions, particularly in width, without increasing the excitation power and reducing the trigger sensitivity.
  • Another object of the invention is to provide an electric holding magnet of simple compact structure which functions with efficiency, effectiveness and reliability.
  • the electric holding magnet of the invention which serves as a tripping device has its legs at the end with the permanent magnet, positioned with the permanent magnet between two plates.
  • the plates comprise material of a higher magnetic saturation than the material of the legs.
  • Each of the plates is in contact with an area of a corresponding one of the legs anda correponding face of the permanent magnet.
  • An electric holding magnet serving as a tripping device for ground leakage circuit breakers has two juxtaposed legs comprising material of high magnetic conductivity, an excitation winding mounted on one end of at least one of the legs, and a permanent magnet atthe other ends of the legs. Portions of the legs in close mutual proximity form a magnetic shunt extending between the permanent magnet and the excitation winding.
  • the holding magnet comprises a pair of spaced substantially parallel plates comprising material of higher magnetic saturation than the material of the legs. The permanent magnet and the legs at their other ends are positioned between the plates. Each of the plates contacts an area of a corresponding one of the legs and a corresponding pole face of the permanent magnet.
  • the plates completely cover the corresponding pole faces of the permanent magnet.
  • the plates contact over large surface areas the portions of the corresponding legs forming the magnetic shunt.
  • a layer of non-magnetic material between the portions of the legs forms the magnetic shunt.
  • the legs comprise a nickel-iron alloy having to by weight of nickel and the plates comprise soft iron.
  • FIG. I is a schematic circuit diagram of a ground leakage circuit breaker
  • FIG. 2 is a side elevation of a known electric holding magnet which may be utilized in the ground leakage circuit breaker of FIG. I;
  • FIG. 3 is a side elevation of an embodiment of an electric holding magnet of the invention.
  • FIG. 4 is a front view of the embodiment of FIG. 3 of an electric holding magnet of the invention.
  • the ground leakage circuit breaker has a summing current transformer having a closed annular magnetic core 22.
  • the transformer has two primary windings comprising two lines 23 and 24 extending through the magnetic core 22, and a secondary winding 25 wound on said magnetic core.
  • the secondary winding 25 is connected to the excitation winding of a holding magnet 27 which serves as the tripping device for a switch actuator 26.
  • the actuator 26 is mechanically coupled, via a switching rod 28, to two switch contacts 29 interposed in the two lines 23 and 24.
  • a load 31 in a grounded metal housing 30 is connected to one phase and the ground conductor of the power supply system via the lines 23 and 24. Normally, just as much current flows through the line 24 from the load 31 back to the line as flows through the line 23 to said load. Therefore, no voltage is induced in the secondary winding 25 of the summing current transformer. If, however, there is a path to the housing 30 from the load 311, part of the current supplied to said load from the system via the line 23, namely, the leakage current, returns to the system via the grounded housing 30. That is, the current returning from the load 31 to the system via the line 24 is smaller than the current flowing to the load via the line 23. The equilibrium of the currents flowing through the summing current transformer is therefore disturbed, and a voltage is induced in the secondary winding 25. The holding magnet-therefore acuates, opens or unlatches the switch actuator 26, and the switch contacts 29 are opened.
  • the known holding magnet shown in FIG. 2 has two flat .legs I and 2 facing each other at their surfaces and is under the influence of a tension spring 4.
  • the leg I carries at the end near an armature 3 a winding 5 serving as the excitation winding.
  • Each of the legs 1 and 2 has at the other end a recess 17 and 18, respectively, which face each other and in which a permanent magnet 6 is positioned in a manner whereby each leg contacts a corresponding pole face of said permanent magnet.
  • the legs I and 2 have extending portions 7 and 8, respectively, facing each other.
  • the extending portions 7 and 8 of the legs 11 and 2 form a magnetic shunt which extends between the excitation winding 5 and the other ends of the legs, at which the permanent magnet 6 is positioned.
  • a narrow air gap 9 is provided between the extending portions 7 and 8 of the legs I and 2.
  • a thin, non-magnetic layer for example, an aluminum foil, may be positioned in the air gap 9.
  • the legs 1 and 2 are held together by a bolt 10 extending through apertures formed through their extending portions 7 and 8.
  • the excitation winding When the excitation winding is energized, it produces a magnetic flux which acts upon the magnetic flux produced in the legs 1 and 2 by the permanent magnet 6. If the part of the magnetic flux which emanates from the permanent magnet 6 and flows through the armature 3 and the legs 1 and 2 at the ends near said armature is sufficiently compensated by the magnetic flux emanating from the excitation winding 5, said armature is lifted from said legs by force of the tension spring 4, whereby the switch actuator 26 (FIG. 1) of the ground leakage circuit breaker is actuated, opened and unlatched.
  • the aforedescribed compensating flux can go through the magnetic shunt and practically does not have to take the path through the permanent magnet 6, which is a poor magnetic conductor.
  • FIGS. 3 and 4 show the holding magnets of the invention.
  • the flat legs 1 and 2 face each other at their surfaces.
  • the ends of the legs 1 and 2 at which the permanent magnet 6 is positioned and said permanent magnet are positioned between two spaced plates or pole pieces.
  • the plates 11 and 12 comprise material of higher magnetic saturation, that is, higher saturation induction, than the material of legs 1 and 2.
  • An aluminum foil having a thickness of 10 microns, for example, may be positioned between portions la and 2a of the legs 1 and 2, respectively.
  • the portions la and 2a of the legs 1 and 2 are in juxtaposition and form the magnetic shunt. This has the effect that, on the one hand, the magnetic resistance of the magnetic shunt is still large enough that a magnetic flux sufficient to produce an adequate holding force goes through the armature 3 and, on the other hand, that the magnetic resistance of said magnetic shunt is still small enough that the holding magnet has a sufficiently high trigger sensitivity.
  • the surface of the plate 11 is in direct contact with the leg 1 and the South pole face S of the permanent magnet 6.
  • the surface of the plate 12 is in direct contact with the leg 2 and the North pole face N of the permanent magnet 6.
  • the legs 1 and 2 and the armature 3 comprise, for example, a nickel-iron alloy having 70 to 80 percent by weight of nickel (mu metal).
  • the plates 11 and 12 advantageously comprise soft steel, which has twice the magnetic saturation, that is, twice the saturation induction, of the nickel-iron alloy.
  • Soft steel is obtained from high carbon raw steel by decarbonizing the raw steel by heating it to a temperature above the melting point, that is, in the molten condition.
  • the magnetic tripping circuit comprising the legs 1 and 2 and the armature 3 of the holding magnet of the invention is of high magnetic conductivity and is not influenced by the plates 11 and 12.
  • the plates 11 and 12 therefore have no effect on the trigger sensitivity of the holding magnet and they need not consist of high permeability material.
  • the magnetic flux required to obtain the holding force for the armature 3 is transferred from the permanent magnet 6 to the legs 1 and 2 via the plates 11 and 12. It is therefore advantageous if the plates 11 and 12 completely cover the pole faces of the permanent magnet 6. It is also preferable that the plates 1 l and 12 contact the portions la and 2a of the legs 1 and 2 forming the magnetic shunt in a large surface area.
  • the magnetic flux transferred from the permanent magnet 6 to the legs 1 and 2 via the plates 11 and 12, of a material having higher magnetic saturation, or saturation induction, than the material of said legs, is greater than the magnetic flux transferred by plates 11 and 12 of the same geometric dimensions but comprising a material having the same magnetic saturation, or saturation induction, as said legs.
  • the holding magnet of the invention has considerably less width B than the known tripping magnet. If the plates 11 and 12 utilized comprise soft steel, the reduction of the width can be approximately 35 percent, whereby up to 50 percent by weight of the relatively expensive nickel-iron alloy, of which the legs 1 and 2 consist, can be saved.
  • An electric holding magnet serving as a tripping device for ground leakage circuit breakers and having two juxtaposed legs comprising material of low magnetic resistance, and excitation winding mounted on at least one of the legs, an armature also of a material of low magnetic resistance engageable with one end of the legs, a permanent magnet engaging the other end of the legs and formed with opposite pole faces, portions of the legs being in close proximity and forming a magnetic shunt extending between the permanent magnet and the armature, and a pair of mutually spaced plates formed of material having a higher magnetic saturation than that of the legs, said permanent magnet and part of the legs being disposed between said plates so that each of said plates abuts an area of one of the legs, respectively, and one of the pole faces, respectively, of said permanent magnet.

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  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Electromagnets (AREA)
  • Breakers (AREA)
US00198796A 1970-11-18 1971-11-15 Electric holding magnet serving as tripping device for ground leakage circuit breakers Expired - Lifetime US3763450A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE19702056627 DE2056627C3 (de) 1970-11-18 Als Auslöser dienender elektrischer Haltemagnet für Fehlerstromschutzschalter

Publications (1)

Publication Number Publication Date
US3763450A true US3763450A (en) 1973-10-02

Family

ID=5788409

Family Applications (1)

Application Number Title Priority Date Filing Date
US00198796A Expired - Lifetime US3763450A (en) 1970-11-18 1971-11-15 Electric holding magnet serving as tripping device for ground leakage circuit breakers

Country Status (13)

Country Link
US (1) US3763450A (xx)
JP (1) JPS5316513B1 (xx)
AT (1) AT311473B (xx)
BE (1) BE775434A (xx)
CA (1) CA949127A (xx)
CH (1) CH532837A (xx)
DE (1) DE7042556U (xx)
DK (1) DK137149C (xx)
ES (1) ES397091A1 (xx)
FR (1) FR2114760A5 (xx)
GB (1) GB1372425A (xx)
IT (1) IT941170B (xx)
ZA (1) ZA717573B (xx)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE19839637A1 (de) * 1998-08-31 2000-03-02 Cmc Carl Meier & Cie Ag Schaff Verfahren zur Herstellung eines Jochs eines Magnetauslösers und Vorrichtung zur Durchführung dieses Verfahrens

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2905275A1 (de) * 1979-02-12 1980-08-21 Felten & Guilleaume Carlswerk Magnetsystem fuer einen ausloeser, insbesondere in einem fehlerstrom-schutzschalter

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
AT251682B (de) * 1963-12-03 1967-01-10 Siemens Ag Haltemagnet für Selbstschalter, insbesondere Fehlerstromschutzschalter
US3302146A (en) * 1965-03-02 1967-01-31 Ite Circuit Breaker Ltd Rotary armature flux shifting device

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
AT251682B (de) * 1963-12-03 1967-01-10 Siemens Ag Haltemagnet für Selbstschalter, insbesondere Fehlerstromschutzschalter
US3302146A (en) * 1965-03-02 1967-01-31 Ite Circuit Breaker Ltd Rotary armature flux shifting device

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE19839637A1 (de) * 1998-08-31 2000-03-02 Cmc Carl Meier & Cie Ag Schaff Verfahren zur Herstellung eines Jochs eines Magnetauslösers und Vorrichtung zur Durchführung dieses Verfahrens

Also Published As

Publication number Publication date
DK137149B (da) 1978-01-23
GB1372425A (en) 1974-10-30
DE2056627B2 (de) 1976-06-10
DE7042556U (de) 1971-04-29
DK137149C (da) 1978-06-26
ZA717573B (en) 1972-08-30
AT311473B (de) 1973-11-26
FR2114760A5 (xx) 1972-06-30
JPS5316513B1 (xx) 1978-06-01
DE2056627A1 (de) 1972-05-31
CA949127A (en) 1974-06-11
IT941170B (it) 1973-03-01
CH532837A (de) 1973-01-15
BE775434A (fr) 1972-05-17
ES397091A1 (es) 1974-05-01

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