JPS6047325A - Circuit breaker - Google Patents

Abstract

(57)【要約】本公報は電子出願前の出願データであるた
め要約のデータは記録されません。(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

【発明の詳細な説明】 〔技術分野〕 本発明は短絡電流等の大電流が流れた際、回路をしヤ断
する回路しゃ断器に関する。DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a circuit breaker that breaks a circuit when a large current such as a short circuit current flows.

〔背景技術〕[Background technology]

この種、回路しゃ断器に於てはそのリンク機構の均整の
崩れによって閉極状態全開極状態にしている。In this type of circuit breaker, the link mechanism is out of balance, causing the circuit breaker to go from a closed state to a fully open state.

而して、そのリンク機構の応答性が遅く、接触子の高速
開極、ひいては高速限流しゃ断が行えなかった。Therefore, the response of the link mechanism was slow, and the contactor could not be opened at high speed, and furthermore, the current limiter could not be cut off at high speed.

特に、高定格容量の大型しゃ断器に於てはその傾向が顕
著である。This tendency is particularly noticeable in large circuit breakers with high rated capacities.

また、接触子部に平行電路を形成して接触子Ｖこ電磁反
発力を作用せしめて高速開極せしＶるものにあっては接
点の開閉による接点の表面状１ｍｌの違いによってその
動作点が著しく変化する欠点があった。In addition, in the case of a device that forms a parallel electric path in the contactor part and applies electromagnetic repulsion to the contactor to open the contact at high speed, the operating point may be affected by a 1ml difference in the surface condition of the contact due to the opening and closing of the contact. It had the disadvantage that it changed significantly.

更に、高定格容量の大型しゃ断器に於−Ｃは定格通電時
の発熱防止Ｊ：太きｆＬ接点圧力を要し、そのためその
接点圧力に抗して反発するためには大きな反発力、ひい
ては犬蹴流を要し、従って動作点全かなり大きく設定し
なければならない欠点があった。Furthermore, in a large circuit breaker with a high rated capacity, -C requires a thick fL contact pressure to prevent heat generation when rated current is applied, and therefore a large repulsive force is required to resist the contact pressure and repel. There was a drawback that a kick flow was required, and therefore the operating point had to be set quite large.

〔発明の１コ的〕 本発明（は上記の点鑑みてなしたものであつ′Ｃ１即ち
ｏＪ動接点板金大電流の磁束下に瞠くヨークに支持シ、
更にこのヨークによって吸引動作するアマチュアを配置
し、このアマチュアの動作によって接圧用と開極用とを
兼ねる１個の引張バネにて可動接点板を瞬時に１聞極動
作することを目的としたものである。[One aspect of the invention] The present invention has been made in view of the above-mentioned points.
Furthermore, an armature is arranged to perform a suction operation by this yoke, and the purpose of this armature is to instantaneously operate the movable contact plate one pole using one tension spring that serves both for contact pressure and for opening. It is.

〔発明の開示〕[Disclosure of the invention]

（実施例） 以下本発明を一実施例として掲げた図面に基すいて説明
すると、１は器台、２はカバーである。(Example) The present invention will be explained below based on the drawings which are shown as an example. Reference numeral 1 indicates a table, and 2 indicates a cover.

３は電源側端子装置、４は固定接点板でこの電源側端子
装置ｉ：Ｈｃ−４を接続し、他端をＵ字型に折り返して
そのＵ字型部５の上片５ａに固定接点６を設けている。3 is a power supply side terminal device, 4 is a fixed contact plate to which this power supply side terminal device i:Hc-4 is connected, the other end is folded back into a U shape, and a fixed contact 6 is attached to the upper piece 5a of the U shape portion 5. has been established.

更にこの上片５１１は電磁反発力により下方に反らない
よう器台１の支柱７１Ｃ受けられている。８は可動接点
、９Ｃ［この可動接点８を自由端の下面に設けた可動接
点で、更に基端９ａ金軸１０＾にて左右側片ｌｉｄ及び
こｆ′Ｌを連らねる上片１１Ｃとの下向の断面コ字型の
磁性アーム１１の中間（Ｃ支持されている。更てこの基
端９ａは過電流動作素子ＷＫ＠ｌ路部１２を介して接続
されている。この電路部１２は具体的ＶＣは編組線を用
いている。而して、この電路部１２が前記アーム１１の
コ字形の上片１１ｃと左右片１１ｄｌ川に囲まれて位置
する。１３はアーム１１の基端１３ｂｆ支持する軸、１
４は下向（ｂコ字型アマチェアで一方が磁性で、他方が
非磁性の左右側片１４ｄ１４ｅ及びこｎ４一連らねる磁
性の下片１４Ｃよりなって身り、前記下向のコ字型磁性
アーム１１の左右１１１１１片１１ｄとアマチュア１４
の左右側片１４’５１４ｅとが対面１１、且つ摺動する
。更にこのコ字型アマチュア１４の左右側片１４ｄ、１
４ｅの基端１４ｈ？コ字型アーム１１の自由端１ｘａｆ
）　左右＋ｔｌ１片ｌｉｄにビン１０ｋ）にて枢支され
、自由端１４３はアーム１１の基端１１ｂと対峙し、且
゛りその下片１４Ｃとアーム１１の）ｉｌｔｃ左右片ｌ
ｉｄとで第３図の矢印に示す磁束の閉回路紮構成する。Furthermore, this upper piece 511 is supported by the support column 71C of the table 1 so as not to warp downward due to electromagnetic repulsion. 8 is a movable contact, 9C [This movable contact 8 is a movable contact provided on the lower surface of the free end, and an upper piece 11C that connects the left and right side pieces lid and f'L at the base end 9a and gold shaft 10^. The middle of the magnetic arm 11, which has a U-shaped downward cross section (C is supported).Furthermore, its base end 9a is connected via the overcurrent operating element WK@l path section 12. Specifically, the VC uses a braided wire.The electric circuit section 12 is located surrounded by the U-shaped upper part 11c of the arm 11 and the left and right parts 11dl.13 is the base end of the arm 11. 13bf supporting shaft, 1
4 is a downward U-shaped amateur chair, one of which is magnetic and the other non-magnetic, consisting of left and right side pieces 14d14e, and a series of magnetic lower pieces 14C; Left and right 1111 pieces 11d of arm 11 and armature 14
The left and right side pieces 14'514e face each other 11 and slide. Furthermore, the left and right side pieces 14d, 1 of this U-shaped armature 14
Base end 14h of 4e? Free end 1xaf of U-shaped arm 11
) The free end 143 faces the base end 11b of the arm 11, and its lower piece 14C and the left and right sides of the arm 11)
id constitutes a closed circuit of magnetic flux as shown by the arrow in FIG.

１６は引張バネＣ１一端士前記可動接点板９の自由端９
ａＶこ他端金アマチュア１４の自由端ｔｅ＠に夫々懸架
し、且つその間を結ぶ線Ｘ−ｘがオン時はｕ１動接点板
９０基端軸１０１１より閉極側に位置し、且つオフ時は
開砒１１１１に位置するようアマチュア１４の自由１ｆ
ｆｆｌ　１４　ａが回転する。16 is the free end 9 of the movable contact plate 9 of the tension spring C1;
aV is suspended from the free end te@ of the metal armature 14, and when the line X-x connecting them is on, it is located on the closing side of the u1 moving contact plate 90 base shaft 1011, and when it is off, Amateur 14 Freedom 1F to be located at Open Arbor 1111
ffl 14 a rotates.

Ｙはアーノ・１１を反転させる／・ノドル幅勅部でアー
ム１１の中央をＩｉｌにて吊動するし套１のリンク片１
８と、仁の第１のリンク片１８と１輛１９に゛Ｃ結合さ
ｎた第２のリンク２０と、この第２のリンク片２０の上
端’１ＩｉＩ＋２１に−Ｃ枢支する引外し板２２と、Ｆ
端ビン２３ｖｃて第１のリンク１８を押し動かす起＠型
ハンドル２４とでなしている。Y is to invert Arno 11/・Hang the center of arm 11 with Iil at the noddle width part and link piece 1 of mantle 1
8, a second link 20 which is connected by C to the first link pieces 18 and 19, and a tripping plate 22 which is pivoted by -C to the upper end '1IiI+21 of this second link piece 20. and F
The end bottle 23vc is made up of a raised @-shaped handle 24 that pushes and moves the first link 18.

また前記過電流動作素子〜Ｖは過′屈流時ンツチ金具２
５．２６が動作して引外し板２２との係合が外ｎ、該引
例外）Ｊｙ、２２が軸２７忙中心に反転し、ハンドルｔ
ｔ２Ｋ　Ｗｈ　ｉｉＢ　Ｙの均整１ｒ崩して゛ｒアーム
■が軸１３倉中心に反転する。２８ンよ固接、へ６，８
に対峙した；′１ｊ弧ｊ）％　Ｑｉである。２９はイ１
荷（、’ｉＱ端子嬰１道で電、ｒ、６部１２金介し″Ｃ
口丁動接点版９に接続さ！シーこいる。：Ｊ　（ｌ　ｉ
ま引張バネで、アマ介ニア１４０目由端］、　４　ａの
軸３１とアーム１１の１Ｉｔ３２ＩＩＡｌｃ懸架されて
おり、アマチュア１４の吸引動作時その吸引動作時その
吸引力に重畳して上ｎ１１１のアーム１１側に回転力を
付与する。３３は圧縮バネで、アーム１１のｔ］由Ｖ晶
１１１の腕片：３５と可動接点板９の自由端９ｎとなる
枠板３４との間に介在【７、常にアーム１１′ｆ：開極
側に弾圧１．でいろっ〔動　作〕 次に本発明の詳細な説明すると、第１図はオン状態であ
って　過電流が流れていない状態である。In addition, the overcurrent operating element ~V is the overcurrent switching fitting 2.
5.26 is operated and the engagement with the tripping plate 22 is outward n, the tripping exception) Jy, 22 is reversed to the center of the shaft 27, and the handle t
t2K Wh iiB Y's symmetry 1r is broken and the ゛r arm ■ is reversed to the center of the shaft 13. 28, fixed, 6,8
′1j arc j)% Qi. 29 is i1
Charge (, 'iQ terminal 1 way electric, r, 6 parts 12 gold via'C
Connected to the mouth moving contact version 9! There's a sea car. :J (l i
It is suspended by a tension spring between the shaft 31 of 4a and the arm 11, and when the armature 14 performs a suction operation, the suction force is superimposed on the suction force of the upper arm n111. Apply rotational force to the 11 side. 33 is a compression spring, which is interposed between the arm piece 35 of the arm 11 (t) of the crystal 111 and the frame plate 34 which becomes the free end 9n of the movable contact plate 9. Oppression on the side 1. [Operation] Next, to explain the present invention in detail, FIG. 1 shows a state in which the device is in an on state and no overcurrent is flowing.

而１−で、第２図の（イ）は過’ｔ４１Ａεが流れた初
期の状態Ｃ１５つて、第３図に示す如くコ字型アマチュ
ア１４の自由端１４１にの磁性側片１４ｄ１下片１４Ｃ
及びコ字型アーム１１の左右１０１１片１１ｄ、上片１
１ｃ、）旧）ニーこｌ４路部１２で作る磁束により該ア
ーム１１の一４端１１１）に吸引され、基端１４ｂを中
心にバネｌ６ＶＣ抗して反時６ｆ方向に回転する。この
時電磁１生側片ｌｉｅがエヤーギヤシブとなって吸引力
が作用する。In 1-, (A) in FIG. 2 shows the initial state C15 in which excess t41Aε flows, and the magnetic side piece 14d1 lower piece 14C on the free end 141 of the U-shaped armature 14 as shown in FIG.
and the left and right 1011 pieces 11d of the U-shaped arm 11, and the upper piece 1
1c,) Old) The knee is attracted to one end 111) of the arm 11 by the magnetic flux generated by the 4-way portion 12, and rotates counterclockwise in the 6f direction around the base end 14b against the spring 16VC. At this time, the electromagnetic first side piece lie becomes an air gear and an attractive force is applied.

この回転によってそのバネ１６の両端の線Ｘ−Ｘが可（
ｄ＋接点板９の支軸１０より開極側（−ヒ側）まで回転
し、アマチュア１４の自由端１４ａはアーム１１の基端
１１１）に当ること（Ｃよって、その自由端１４１１を
中心に町＠γ点板９の自由端９亀が時計方向（・こ反転
し、同図の（ハ）の如く開極する。This rotation allows the line X-X at both ends of the spring 16 to change (
d+ The contact plate 9 rotates from the support shaft 10 to the opening side (-H side), and the free end 14a of the armature 14 hits the base end 111 of the arm 11. @The free end 9 of the γ point plate 9 is reversed clockwise and opened as shown in (c) in the same figure.

〔光明の効宋〕[Effect of Light Song Dynasty]

本発明は上記の如く、可動゛接点８を自由端に有し、且
つ基端ケ軸１０ａにて支持した可動接点板９と、この可
動接点板９の基端と過電流動作老子Ｗとを接恍する厄：
塔部１２と、このｔＪＬ路部１２に流れた大゛ｄイ流（
（よる磁束のヨークとなると共に、前記可動接点−仮９
０基端輛１０を支持し、而もハンドル２４にて基端ヤ支
浦１３を中心に反転する磁性ノアーム１１と、Ｗｂてこ
のアーム１１の自由端に基端を枢支し、且つ自由端を該
アーム１１の基端と対峙したアマチュア１４と、前記可
動接点板９の自由端９ａとアマチュア１４の自由端１４
ｂとの間に懸架された引張バネ１６とでなり、而も該引
張バネ１６はオン時に於てその両懸架点を結ぶ線Ｘ−Ｘ
が可動接点板９の基端の軸１０１点より閉極側に位置し
、オフ時は開極側に位置するようアマチュア１４の自由
端１４ｂがアーム１１に吸引されようにしたから、１個
の引張バネ１６にて接圧と開極と全兼用でき、且つ該バ
ネ１６は開極時ある時点からそのアマチュア１４の吸引
方向と同方向に作用し、従って比較的小さな設定動作電
流によりアマチュア１４は動作し、もってリンク機構開
放の遅れの問題を解決でき、高定格しゃ断器に対応でき
る。As described above, the present invention includes a movable contact plate 9 having a movable contact 8 at the free end and supported by the proximal end shaft 10a, and a movable contact plate 9 having the movable contact 8 at the free end and the overcurrent operation terminal W connected to the proximal end of the movable contact plate 9. The evil that comes into contact:
A large flow (
(Becomes a yoke of magnetic flux due to
A magnetic arm 11 that supports the base end vehicle 10 and rotates around the base end shaft 13 using the handle 24; the armature 14 facing the base end of the arm 11, the free end 9a of the movable contact plate 9, and the free end 14 of the armature 14.
A tension spring 16 is suspended between the tension spring 16 and the tension spring 16.
Since the free end 14b of the armature 14 is attracted to the arm 11 so that it is located on the closing side from the shaft 101 point at the base end of the movable contact plate 9, and on the opening side when turned off, one The tension spring 16 can be used for both contact pressure and opening, and the spring 16 acts in the same direction as the attracting direction of the armature 14 from a certain point when opening the armature. This solves the problem of delay in opening the link mechanism, and can support high-rated circuit breakers.

（に本発明はＩｊＴ動接動板点板９補ｒろアームｌｌを
下向のコ字苓形成し、且つアマチュア１４金上同のコ字
状に形成して両者１１、ｌ　４　（１）左右側片１１ｆ
＋、１４（入　１４ｅ金対而させると４辷に、そのアマ
チュア１４の一方側片１４ｃを非磁性とじたから、アー
ム１１とアマチュアとで作る磁束がそのコ字型に涜って
強力に作用し、もってアマチュア１４の吸引力が向上し
、より優れたしゃ断時性が得られる効果がある、(In the present invention, the IJT movable contact plate point plate 9 supplementary arm 11 is formed into a downward U-shape, and the amateur 14-karat gold upper part is formed into the same U-shape, so that both 11 and 14 (1) Left and right side piece 11f
+, 14 (Enter 14e) Since one side piece 14c of the armature 14 is non-magnetic bound on all four sides when the armature 14e is held against gold, the magnetic flux created by the arm 11 and the armature acts strongly against the U-shape. , which has the effect of improving the suction power of the amateur 14 and providing better shutoff performance.

【図面の簡単な説明】 図面は本発明Ｆφ１路しゃ断器の一実焔例を示し、第１
図は断面正面図、第２図は動作［Ａ％Ｆｇ３図目、拡大
要部図である。 ５・・・固定接点板、６・・・固尼接屯、８・・・可動
接点９・・・可動接点板、１０・・・軸、１１・・・コ
字ｔｌＬアーム１２・・・電路ご１１１３・・・軸・・
・　１４・・・コ字型アマヌユア、１６・・・バネ、２
５・・・）１ンドル特許出ぶ人 松下屯工株式会社 代理人弁理士　竹　元　敏　丸 （ほか２名） 第２図 （イ） 讃 第３図 第４図 １ｃ 手続補正書（方力 ■、事件の表示 １１１卦１１５８年特許願第１４０１７７号２　発明の
名称 回路しゃ断器 ３、補正をする者 事件との関係　特許出願人 住　所　大阪府門真市大字門真１０４８番地名　称（５
８３）松下電工株式会社 代表者　小　林　郁 ４、代理人 住　所　大阪府門真市大字門真１０４８番地６、補正の
対象 手続ネｔｌｊ正１： 昭和５９年　９月２１日 特許庁長官　殿 １、事件の表示 回路しゃ断器 ３、補正をする者 事件との関係　特許出願人 住　所　大阪府門真市大字門真１０４８番地名　称（５
８３）松下電工株式会社 代表者　小　林　郁 ４、代理人 住　所　人１初イ）門真用大字門真１０４８番地明細書 補正の内容 （１）特許請求の範囲を別紙の通りに補正する。 （２）　明細書第３頁７行目の「上記の点」の次に［に
ｊを１車入する。 （３）明細Ｗ第４頁８行目に１−過電流動作素子Ｗに電
路部１２」とあるを［負荷側端子装置２９に電路部１２
及び過電流動作素子Ｗ」に補正する。 （４）　明細書箱５頁１０行目に「するよう」とあるを
「するものであり、従ってオフ時にはこの引張ハネ１６
により」に補正する。 （５）明細書箱５頁１９行目の［過電流動作素子Ｗは過
電流時」の次に１周知の引き外しリンク機構を作動せし
める。ずなわら、実施例では−１を挿入する。 （６）明細書第６頁４行目乃至６行目の１−２９は−−
る。」を削除する。 （７）明細書第６頁８行目の「吸引動作時その」を削除
する。 （８）明細書第７ｗ１５乃至１６６行目［過電流動作歯
−７Ｗ」とあるを［負荷側端子装置２９」に？＋ｌｉ正
する。 （９）明細書第８頁９行目に「吸引されように」とある
を「吸引されるように」にネ＋ｔｉ正する。 ２、特許請求の範囲 （１）固定接点を有する固定接点板と、この固定接点と
瓢１合する可動接点を自由端に有し、且つ基部１を軸に
て支持した可動接点板と、この可動接点板の基端と電源
側又は負荷側端子装置とを接続する電路部と、この電路
部に流れた入電流による磁束のり−クとなると共に、前
記可動接続板の基端軸を支持し、而もハンドルにて基☆
１ｊｌｌの支軸を中心に反転する下向のコ字型磁性アー
ムと、更にこのコ字型磁性アームの左右側片に対面する
と共に枢支される一方が磁性で、他方が非磁性の左右側
片及びこれを連らねる磁性の下片とでなる上向のコ字型
アマチュアと前記可動接点板の自由端とアマチュアの自
由端との間に懸架されると共に、オン時に於てその両懸
架点を結ふ線が可動接点板の乱端の軸点より閉極側に位
置し、オフ時は開極側に位置するようアマチュアの自由
端が了−ムに吸引される引張ハネとでなしたことを特徴
とした回路しゃ断器。 代理人弁理士　竹元　敏丸[BRIEF DESCRIPTION OF THE DRAWINGS] The drawing shows an example of an Fφ1 road breaker according to the present invention.
The figure is a cross-sectional front view, and Figure 2 is an operation [A%Fg Figure 3 is an enlarged view of the main parts. 5... Fixed contact plate, 6... Fixed contact plate, 8... Movable contact 9... Movable contact plate, 10... Shaft, 11... U-shaped tlL arm 12... Electrical circuit Go1113... Axis...
・ 14... U-shaped Amanuyua, 16... Spring, 2
5...) Person who issued a $1 patent Patent attorney for Matsushita Tunko Co., Ltd. Toshimaru Takemoto (and 2 others) Figure 2 (a) San Figure 3 Figure 4 Figure 1c Procedural amendment (Houli ■ , Indication of the case 111 Hexagram 1158 Patent Application No. 140177 2 Name of the invention Circuit breaker 3, Person making the amendment Relationship to the case Patent applicant address 1048 Kadoma, Kadoma City, Osaka Prefecture Name (5)
83) Matsushita Electric Works Co., Ltd. Representative Iku Kobayashi 4, Agent address 1048-6 Kadoma, Kadoma City, Osaka Prefecture, Procedures subject to amendment 1: September 21, 1980 Commissioner of the Patent Office Tono 1, Incident Display circuit breaker 3, relationship with the amended case Patent applicant address 1048 Kadoma, Kadoma City, Osaka Name (5)
83) Matsushita Electric Works Co., Ltd. Representative: Iku Kobayashi 4, Agent address: 1048 Oaza Kadoma Contents of amendment to the specification (1) The scope of the claims will be amended as shown in the attached sheet. (2) Insert one j into the box next to "the above point" on page 3, line 7 of the specification. (3) In the 8th line of page 4 of the specification W, change the line 1--Cable circuit section 12 to overcurrent operating element W to [Circuit circuit section 12 to load-side terminal device 29].
and overcurrent operating element W. (4) On page 5, line 10 of the statement box, the phrase ``to do'' has been replaced with ``to do'', so when off, this tension spring 16
Corrected to "by". (5) Next to "Overcurrent operating element W is activated during overcurrent" on page 5, line 19 of the statement box, a well-known tripping link mechanism is activated. However, in the embodiment, -1 is inserted. (6) Lines 1-29 of page 6 of the specification, lines 4 to 6, are --
Ru. ” to be deleted. (7) Delete "when suction operation occurs" on page 6, line 8 of the specification. (8) Lines 7w15 to 166 of the specification, "Overcurrent operation tooth -7W" should be replaced with "Load side terminal device 29"? +li Correct. (9) In the 9th line of page 8 of the specification, the phrase ``as if sucked in'' was corrected to ``so as to be sucked''. 2. Claims (1) A fixed contact plate having a fixed contact, a movable contact plate having a movable contact mating with the fixed contact at the free end, and supporting the base 1 by an axis; An electric circuit section that connects the base end of the movable contact plate and the power supply side or load side terminal device, and serves as a magnetic flux flux due to the incoming current flowing through this electric circuit section, and supports the base end shaft of the movable connection plate. , and also based on the handle ☆
A downward U-shaped magnetic arm that rotates around the support axis of 1jll, and furthermore, one side that faces and is pivoted to the left and right pieces of this U-shaped magnetic arm is magnetic and the other is non-magnetic. An upward U-shaped arm consisting of a magnetic lower piece and a magnetic lower piece connected thereto is suspended between the free end of the movable contact plate and the free end of the armature, and both suspensions are suspended when turned on. The free end of the armature is drawn by a tension spring to the end so that the line connecting the points is located on the closed side from the axis point of the random end of the movable contact plate, and on the open side when turned off. A circuit breaker characterized by: Representative Patent Attorney Toshimaru Takemoto

Claims (1)

【特許請求の範囲】[Claims] （１）固定接点を有する固定接点板と、この固定接点と
離合する可動接点を自由端に有し、且つ基端を軸にて支
持した可動接点板と、このｆｉＪ動接動板点板端と過電
流動作素子とを接続するＩに路部と、この電路部に流れ
た大電流による磁束のヨークとなると共に、前記可動接
点板の基端軸を支持］７、而もハンドルにて基端の支軸
を中心に反転するＦ向のコ字型磁性アームと、更にこの
コ字型磁性アームの左右側片に対面すると共に枢支され
る一方が磁性で、他方が電磁の左右側片及びこれを連ら
れる磁性の下片とでなる上向のコ字型アマナユアと前記
可動接点板の自由端とアマチュアの自由端との間に懸架
されると共に、オン時に於てその；１ｊ懸架点を結ぶ線
が可動接点板の基端の軸点より閉極側に位置し、オフ時
は開極側に位置するようアマチュアの自由端がアームに
吸引される引張バネとでなした特徴とした回路しゃ断器
。(1) A fixed contact plate having a fixed contact, a movable contact plate having a free end that has a movable contact that separates from the fixed contact and whose base end is supported by a shaft, and an end of this fiJ movable contact plate. and the overcurrent operation element, and a path section that serves as a yoke for the magnetic flux due to the large current flowing through this circuit section, and also supports the base end shaft of the movable contact plate. A U-shaped magnetic arm that rotates in the F direction around a support shaft at the end, and one side that faces and is pivoted to the left and right pieces of this U-shaped magnetic arm is magnetic, and the other is electromagnetic. and a magnetic lower piece connected thereto, the upper U-shaped armature is suspended between the free end of the movable contact plate and the free end of the armature, and when turned on, the suspension point 1j The free end of the arm is drawn into the arm by a tension spring so that the line connecting the movable contact plate is located on the closing side from the axis point at the base end of the movable contact plate, and on the opening side when off. circuit breaker.