GB2295275A

GB2295275A - Circuit breaker

Info

Publication number: GB2295275A
Application number: GB9509096A
Authority: GB
Inventors: Takashi Kitamura; Yoichi Tokoyama; Yoichi Kunimoto; Tomoyuki Sawada; Hirofumi Konishi
Original assignee: Matsushita Electric Works Ltd
Current assignee: Panasonic Holdings Corp
Priority date: 1994-11-15
Filing date: 1995-05-04
Publication date: 1996-05-22
Anticipated expiration: 2015-05-04
Also published as: GB9509096D0; MY113997A; HK1012125A1; GB2295275B; CN1068703C; CN1147140A

Abstract

A circuit breaker comprises first and second spring biased movable contacts 33x, (33y, Fig 1) engageable with respective fixed contacts 31x, (31y) and a link 48 connecting the movable contacts together for ganged movement. The link 48 has two legs, one of which 48a is coupled to an operating handle 41 and the other of which 48b is coupled to the first movable contact 33x and to the lower end of a pivotable member (121) carrying the second movable contact (33y). The upper end of the contact carrier (121) is pivotable about an axis parallel to the other leg 48b of the link 48. In response to a leakage current detected by a current transformer (92), an electromagnetic actuator (100) is operated to trip the circuit breaker and to move an indicator (133) against the bias of a spring (134) to an actuation indicating position in which it is held by a latch (131). <IMAGE>

Description

CIRCUIT BREAKER The invention concerns a circuit breaker that is inserted in a single-phase distribution circuit equipped with a voltage line and a ground line.

In order to protect circuits, including single-phase distribution circuits, triple-phase distribution circuits and other such distribution circuits, circuit breakers are ordinarily inserted at a variety of locations in distribution circuits. Hence, there is a need for a variety of circuit breakers having different numbers of poles, such as single-pole, di-pole, tri-pole, quad-pole, and so forth. But with separate manufacturing of the various circuit breakers having different numbers of poles, there is an increase in manufacturing cost. In order to hold down the increase in manufacturing cost through incorporation of common parts, the concept of manufacturing a single-pole circuit breaker and coupling together as many as needed for the required number of poles has evolved, as, for example, in the invention described in Japanese Patent Publication (KOKOKU) No. 1-33019.

Single-phase distribution circuits possess voltage lines and ground lines, and the voltage lines and ground lines respectively have contacts inserted from circuit breakers used in single-phase distribution circuits. Moreover, when a release mechanism senses an abnormality in the current flowing through a main current path wherein the contacts are inserted, the circuit breaker actuates a drive mechanism and causes contacts inserted in the voltage line and ground line to open. Since the ground line is grounded to earth, no current will flow to ground despite there being a short to ground, and when load-side current consumption increases above rated current, an abnormal current can be sensed at the voltage-line side.Accordingly, it is sufficient that the release mechanism be able to sense a current abnormality at the voltage-line side only, and that the drive mechanism be constituted so as to allow ganged opening of voltage-line-side and ground-line-side contacts.

Adoption of this constitution makes a release mechanism at the ground-line side unnecessary, and permits shared use of the drive mechanism by the voltage-line-side and ground-line-side contacts, thereby reducing the parts count. The invention described in Japanese Patent Publication (KOKOKU) No. 2-31454 adopts a constitution wherein a drive mechanism is arranged in the region between the voltage-line-side and ground-line-side contacts, and sensing of a voltage-line-side current abnormality by the release mechanism results in the simultaneous opening/closing of the voltage-line-side and ground-line-side contacts. This constitution permits stabilization of voltage-line-side and ground-line-side contact open/close timing, and also permits an increase in contacting state reliability at the contacts.

The former constitution possesses the advantage of permitting incorporation of common parts in circuit breakers having different numbers of poles. The latter constitution possesses the advantage of permitting reduction of the parts count in circuit breakers used in single-phase distribution circuits. Yet, while the former circuit breaker's coupling of single-pole circuit breakers allows incorporation of common parts in circuit breakers having different numbers of poles, application of the latter circuit breaker's art to reduce the parts count is difficult.

In effect, if single-pole circuit breakers are to be joined and used in a single-phase distribution circuit possessing a voltage line and a ground line, we can conceive of a constitution employing the same type of circuit breaker at the voltage-line side and the ground-line side, and we can conceive of a constitution employing different types of circuit breakers at the voltage-line side and the ground-line side. Yet, if the same type of circuit breaker is employed, the parts count cannot be reduced. To reduce the parts count, we must adopt a constitution wherein a voltage-line-side circuit breaker equipped with both a release mechanism and a drive mechanism is joined to a ground-side circuit breaker equipped with neither a release mechanism nor a drive mechanism.It will in this case be necessary to gang the ground-lineside circuit breaker contacts to the voltage-line-side circuit breaker contacts, but merely joining them will result in occurrence of the problems of voltage-line-side and ground-line-side contact open/close timing destabilization, and loss of ability to ensure reliability of the contacting state at the contacts.

The invention was conceived in light of the above reasons, with the purpose of providing a circuit breaker whereby installing a drive mechanism and a release mechanism only at the voltage line is sufficient even though contacts are respectively inserted in a voltage line and a ground line, and wherein voltage-line-side and ground-lineside contact open/close timing is stable and a highly reliable contacting state is afforded.

In the invention, in the context of a circuit breaker equipped at one end with a pair of fixed contacts with movable contacts respectively opposed thereto, wherein contact-opening springs are respectively elastically mounted at the other end, and which is equipped with first and second movable contactors that open and close the spaces between the fixed contacts and the movable contacts as a result of actuation of the regions between the movable contacts and the contactopening springs, an actuation handle capable of open/close actuation of the first and second movable contactors, a drive mechanism that enables open/close actuation by the actuation handle as a result of linkage between the actuation handle and the first and second movable contactors and that opens the spaces between the fixed contacts and the movable contacts as a result of removal of linkage, and a release mechanism that removes the linkage between the actuation handle and the first and second movable contactors by the drive mechanism when an abnormality is sensed in the current flowing through main current path passing through the fixed contacts and the movable contacts when the fixed contacts and the movable contacts are in a closed state, a pinshaped contactor link provided at the drive mechanism is inserted through the region between the contact-opening spring and the movable contact of the first movable contactor to join the drive mechanism and the first movable contactor, a swiveling movable member is provided whose center of rotation is an axis parallel to the contactor link, the aforesaid contactor link is joined at a region other than the center of rotation of the movable member, and the region between the contact opening spring and the movable contact on the second movable contactor is retained by the movable member such that the movable contact provided at the second movable contactor disengages from the fixed contact in accompaniment to swiveling of the movable member accompanying movement of the contactor link when the movable contact provided at the first movable contactor disengages from the fixed contact. By virtue of the fact that the first movable contactor is directly coupled to the contactor link of the drive mechanism, the space between the movable contact and the fixed contact can be opened and closed with certainty.With respect to the second movable contactor, since it is retained by a swiveling movable member around a prescribed axis as its center of rotation, the center of rotation of the movable member remains stable despite any play that might exist in the movement of the contactor link, such that stable opening and closing of the second movable contactor is allowed. In short, the first movable contactor is provided at the voltage-line side, the second movable contactor is provided at the ground-line side, and the drive mechanism and the release mechanism are provided at the first movable contactor only, thus permitting reduction of the parts count. Yet because a movable member with a stable center of rotation is used to gang opening/closing of the second movable contactor to the first movable contactor, open/close timing is stabilized and contacting state reliability is improved.

The aforesaid contactor link is formed from metal, and the movable member is formed from an insulating synthetic resin. Thus, by making the contactor link out of metal, the coupling strength between the first movable contactor and the second movable contactor is increased, and open/close timing is made all the more stable; furthermore, by making the movable member out of an insulating synthetic resin, insulation between thefirst movable contactor and the second movable contactor can be maintained.

The invention is equipped with a zero-phase current transformer, which senses the current flowing through both fixed contacts and both movable contacts, and is equipped with an electromagnet mechanism, which removes the linkage caused by the drive mechanism between the first and second movable contactors and the actuation handle when an abnormality in the current flowing through a main current path is sensed by the zero-phase current transformer. The housing is provided with two compartments separated by an insulator partition. The first movable contactor, the actuation handle and the drive mechanism are arranged within one compartment, while the second movable contactor, the zero-phase current transformer, and the electromagnet mechanism are arranged within the other compartment.Because the members that sense abnormalities due to electrical leakage are provided within a compartment that is separate from the drive mechanism and the release mechanism, by providing a drive mechanism and a release mechanism at only the voltage-line side in a device equipped with contacts at the voltage-line side and the ground-line side, the excess space at the compartment formed at the ground-line side can be utilized to provide interrupter function for electrical leakage. Hence, a small, highperformance circuit breaker can be provided.

In addition, in the invention an indicator capable of movement between an indicating position and a non-indicating position in order to indicate operation of the electromagnet mechanism is energized by a push spring toward the non-indicating position. Since no restoring force is stored in the spring at the non-indicating position, definitive prevention of indicator error is enabled with no movement of the indicator to the indicating position under action of vibration, shock, or other such external forces. In particular, in a circuit breaker equipped with the combined functions of sensing of overload or short and subsequent interruption of a main current path, actuation of the drive mechanism at the time of overload or short produces vibration and shock.Notwithstanding a circuit breaker being of such design, adoption of the above constitution permits interruption under electrical leakage to be clearly distinguished from interruption due to overload or short. Since the indicator is engaged, with the push spring in a state wherein restoring force is stored, during interruption of a main current path under electrical leakage the indicator can be made to return to the non-indicating position merely by removal of the engagement, with the result that reduction of the parts count as compared to the conventional constitution is made possible.

Employment of a plunger at the electromagnet mechanism permits a large suction force to be obtained despite small size.

Although rotation-operated the effect of friction at the ganging lever is small, so it is possible for the electromagnet mechanism to exert a large force at the indicator while still employing an electromagnet mechanism that is relatively small in size, thereby enabling definitive interruption of the main current path and indication of electrical leakage upon sensing of electrical leakage.

In a preferred embodiment of the invention, the primary side of a zero-phase current transformer is equipped with a test switch that can be actuated so as to simulate flow of an unbalanced current. The test switch is equipped with a flexible movable member that receives pressure from a push button, and with a contactor plate which opposes a part of the movable member and which comprises a contact. The electrical leakage interruption means are equipped with a positioning projection that presses so as to direct the movable member to disengage from the contactor plate during contact-opening driving of the movable contactor. The position on the movable member contacted by the contactor plate is located nearer to the tip of the movable member than the position acted upon by the pressure from the push button.The point acted upon by the pressure from the positioning projection is located between the position on the movable member contacted by the contactor plate and the position acted upon by the pressure from the push button. Since the position on the movable member contacted by the contactor plate is located nearer to the tip of the movable member than the position acted upon by the pressure from the push button, and the point acted upon by the pressure from the positioning projection is located between the position on the movable member contacted by the contactor plate and the position acted upon by the pressure from the push button, when sensing of electrical leakage results in interruption of a main current path and the positioning projection causes pressure to be exerted that is directed at the movable member so as to draw it away from the contactor plate, a region opposing the contactor plate at a position on the movable member that is nearer to the tip than the region receiving the pressure from the positioning projection can be definitively drawn away from the contactor plate. Moreover, because in this constitution the distance of the movable member from the contactor plate will be as large as the pressure from the push button is strong, continuation of the ON state at the test switch following interruption of the main current path can be definitively prevented.

An fsubodinmt of the invention will now be described, by way of exawle only, with reference to the accanpanying drawls in Aiich: Fig. 1 is an oblique exploded view showing the ground-electrode side of the circuit breaker in one embodiment of the invention.

Fig. 2 is an oblique view of the above circuit breaker with the ground electrode-side cover removed.

Fig. 3 is an oblique exploded view of the voltage-electrode side of the above circuit breaker.

Fig. 4 is an oblique view of the above circuit breaker with the voltageelectrode-side cover removed.

Fig. 5 is an oblique exterior view showing the above circuit breaker.

Fig. 6 is a lateral cross-sectional view showing the above circuit breaker.

Fig. 7 is a circuit diagram of the above circuit breaker.

Fig. 8 is a side view of the above circuit breaker with the voltage electrode-side cover removed, showing the closed-contacts state.

Fig. 9 is a side view of the above circuit breaker with the ground electrode-side cover removed, showing the closed-contacts state.

Fig. 10 is a side view of the above circuit breaker with the voltage electrode-side cover removed, showing the open-contacts state.

Fig. 11 is a side view of the above circuit breaker with the groundelectrode-side cover removed, showing the open-contacts state.

Fig. 12 is a side view of the above circuit breaker with the voltageelectrode-side cover removed, showing the tripped state.

Fig. 13 is a side view of the above circuit breaker with the groundelectrode-side cover removed, showing the tripped state.

Fig. 14 is a cross-sectional plan view of the principal parts of the above circuit breaker.

Fig. 15 is a side view of the principal parts of the above circuit breaker with the ground-electrode-side cover removed, showing the closedcontacts state.

As shown in Fig. 1 through Fig. 6, the circuit breaker of the invention is equipped with housing 10 composed of an insulating synthetic resin, and housing 10 is formed by joining, using rivets 11 (see Fig. 5), body l0a and a pair of covers lObx and lOby that respectively cover both sides of body 10a. In other words, assembly through-holes 12a, 1 2box, and 12by are provided at four peripheral locations on body 1 ova and on each of covers 1 Obx and lOby, and by respectively passing rivets 11 through assembly through-holes 12a, 12bx, and 12by, joining of body l0a and both covers lObx and lOby is accomplished.Compartments are respectively formed between body l0a and each of covers lObx and lOby. Contacts 30x, which are inserted in the voltage line, are housed within the compartment between body l0a and cover lObx, while contacts 30y, which are inserted in the ground line, are housed within the compartment between body lOasand cover lOby. Below, we refer to the cover lObx side with respect to body 10a as the "voltage-electrode side," and we refer to the cover lOby side with respect to body 10a as the "ground-electrode side." Housing 10 is provided at both its front and its back end with one pair each of movable-side terminals 20ax and 20ay, and fixed-side terminals 20bx and 20by.Terminal plates 21ax and 21ay, which are equipped with fixed contacts 31x and 31y (see Fig. 1 and Fig. 3), are connected electrically to movable-side terminals 20ax and 20ay. Here, we will first describe the constitution of the voltage-electrode side.

Terminal plate 21bx, which is fastened to one end of bimetallic element 61 making up thermal release mechanism 60, is connected electrically to fixed-side terminal 20bx of voltage-electrode side. Fixed contact 31x, together with movable contact 32x provided on movable contactor 33x, makes up contacts 30x. Movable contactor 33x disengages from fixed contact 31 x in correspondence to operation of drive mechanism 40, to be described below. Movable contactor 33x is connected electrically, through jumper line 37x, which is made of braided wire, to one end of coil 51 of electromagnetic release mechanism 50, to be described below, and the other end of coil 51 is connected, through jumper line 38x, which is made of braided wire, to the mid-region of bimetallic element 61.Accordingly, when contacts 30x close, current will flow in the main current path formed by the following route: movable-side terminal 20ax contacts 30x - coil 51 - bimetallic element 61 -- fixed-side terminal 20bx. An intermediate region of jumper line 38x passes through passage-hole 19a provided in body 1 Oa and enters the ground-pole-side compartment. This constitution will be described below. Bimetallic element 61 may employ either the directly heated design, which is of the sort that bends due to self-heating, or the indirectly heated design, wherein a flat heater is laminated, and heating from the heater causes bending.

Handle through-hole 13 with rectangular opening is formed at the top surface of housing 10 when body 10a and cover 1 Obx are butted together. As shown in Fig. 3, cylindrical bearing 14 protrudes in the vicinity of handle through-hole 13, at the interior surface of body 1 0a and cover 1 Obx. The respective ends of handle shaft 42, on which actuation handle 41 pivots, are inserted into the bearing holes 14a in the centers of bearings 14. Operation member 41a provided on actuation handle 41 is inserted through handle insertion hole 13 such that it protrudes from the upper surface of housing 10. In other words, actucation handle 41 rotates freely around handle shaft 42 over the range of motion of operation member 41 a in handle insertion hole 13.

Arc-shaped cover piece 41 b is formed at the base of operation member 41 a of actuation handle 41 with handle shaft 42 as its center, and housing 10 is bulged outward in the area around handle insertion hole 13 to conform to cover piece 4 lib. Cover piece 41b slidably contacts the inside surface of housing 10 and shuts out the inside of housing 10 to be invisible even when actuation handle 41 is rotated. Lettering is provided on cover piece 14b to indicate the open/closed state of the breaker contacts 30x with the operation of actuation handle 41.Link support member 41 c is mounted on the lower surface of cover piece 4lib, with shaft tabs 41d mounted on both sides of the bottom of link support 41c. Operation member 41a and link support member 41c protrude from cover piece 41b such that they are angled with one another rather than being aligned. Additionally, actuation handle 41 is energized to the counter-clockwise as viewed in Fig. 3, by a handle return spring 43 installed around the periphery of bearing 14. One end of handle return spring 43 is secured at the right edge of cover piece 41b as seen in Fig. 4, and the other end at trip plate 44 of the drive mechanism 40 described below.

The drive mechanism 40 is made up of trip plate 44, generally U-shaped handle link 45, latch plate 46, and contact link 48. Shaft tabs 41d on actuation handle 41 are inserted through the bearing holes 45a formed at the end of each leg of handle link 45. Latch plate 46 is made up of flat-plate-type stop plate 46a and a pair of guide members 46b that extend parallel to each other from the ends thereof. Handle shaft 42 is inserted through shaft openings 46c formed at the leading ends of guide members 46b. Trip plate 44 is pivotally supported in housing 10 by shaft pin 47, with both ends of shaft pin 47 being inserted in bearing hole 1 spa formed in bearings 15 formed on the inner surfaces of body 10a and cover lob. Contact link 48 is formed in a general U-shape, and has one leg member 48a inserted through link holes 45b, which are formed in the base portions of the two legs of handle link 45, and through guide holes 46d, which are formed in the two guide members 46b of latch plate 46. The other leg 48b of contact link 48 is inserted through shaft openings 33a provided in movable contact 33x. A guide channel 16 curved to form a convex arc is formed below (as seen in Fig.

3), on the inside surface of body 10a. Inserting the end of leg 48b of contact link 48 into this guide channel 16 results in the range of motion of contact link 48 being regulated by guide channel 16.

Movable contact 33x is furnished with movable contact point 32x on one end and spring receiver member 33bx on the other end, and has a pair of lib 33c with shaft openings 33a, which shaft leg 48b of contact link 48 is inserted into and located between movable contact point 32x and spring receiver member 33bx. Movable contact point 32x is formed at the angle created by bending one end of movable contact 33x into a general L-shape, with arc runner member 33d extending out past movable contact point 32x to the end. Mounted on spring receiver member 33bx is a spring seat that is inserted into one end of contact pressure spring 34x, a coil spring. The other end of contact pressure spring 34x is received in spring receiver recess 35x, formed on the inner surface of body 10a. Stopper 36 is mounted on the inner surface of body 1 Oa, facing the opening surface of spring receiver recess 35x.Contact pressure spring 34x and spring receiver member 33bx are inserted into the space between the inner surface of body 10a, in which spring receiver recess 35x is formed, and stopper 36. Spring receiver member 33bx is energized toward stopper 36 by the spring force of contact pressure spring 34x.

Trip plate 44 is formed into a shape wherein a first push pressure member 44b is mounted extending from the top end of base member 44a to one side, while a second push pressure member 44c extends downward from base member 44a, and in addition, arm 44d is provided extending from the edge on one side of base member 44a midway between the top and bottom in a direction generally perpendicular to base member 44a. Shaft pin 47 is inserted in the base portion of arm 44d such that trip plate 44 rotates freely around shaft pin 47. Moreover, hook notch 44e is formed in the upper edge of the leading end of arm 44d, while farther out toward the end of arm 44d than hook notch 44e, the top edge of arm 44d slopes so as to approach the bottom edge. Also, retainer notch 44f is formed on the side edge of base member 44a as an upward-cut, opening toward the side.Trip plate 44 is energized counter-clockwise (as seen in ) by retaining one end of handle return spring 43 in this retainer Fig. 3 notch 44f.

Latch plate 46 can be rotated freely with respect to housing 10 by handle shaft 42 and actuation handle 41, but the range of movement of latch plate 46 with respect to actuation handle 41 is regulated by the fact that leg 48a of contact link 48, which is inserted in handle link 45, is inserted in guide holes 46d of latch plate 46, and handle link 45 is pivotally supported on shaaft tabs 41d of actuation handle 41.

Moreover, the lower edge of stop plate 46a of latch plate 46 can be engaged with hook notch 44e provided in trip plate 44. In the engaged state, latch plate 46 is prevented from being moved.

As described above, drive mechanism 40, made up of actuation handle 41, handle shaft 42, handle return spring 43, trip plate 44, handle link 45, latch link 46, shaft pin 47, and contact link 48, functions through the action of electromagnetic release apparatus 50 or thermal release apparatus 60 to cause the breaker contacts 30x to open when excessive current passes through the main electrical path with the breaker terminals in the closed state.

Electromagnetic release apparatus 50 is furnished with yoke 52 which is made of magnetic material formed in an upward-opening general U shape, with coil 5 1 disposed within the space inside yoke 52.

Yoke 52 is furnished with a pair of side members 52a and 52b facing the two axial end surfaces of coil 51, and base member 52c, which passes below coil 51 and joins the interval between the two side members 52a and 52b. Retainer grooves 52d and 52e are formed in side members 52a and 52b, respectively. Coil 51 is disposed around cylinder-shaped coil tube 53, which is made of electrically insulating material. Flange 53a is formed in one piece at one axial end of coil tube 53, and a narrowed section 53b in which both the inside and outside diameters are smaller than those of an intermediate section in the axial direction is formed at the other axial end of coil tube 53.

Plunger 54, having a section where the diameter is larger than the inside diameter of narrowed section 53b, is disposed within the inside space of coil tube 53 such that it can move freely in the axial direction of coil tube 53. Fixed core 55 is mounted in coil tube 53 opposite plunger 54 at the flange 53a end of coil tube 53 such that a portion of it protrudes from coil tube 53. One-piece catch pin 54a is provided at one of the end surfaces in the direction of travel of plunger 54 such that it protrudes from the end surface of the narrowed section 53b of coil tube 53. Opposed to the other end is push pressure pin 57, which passes through fixed core 55 and protrudes from the end surface of coil tube 53 at its flange 53a end. Formed at the leading end of catch pin 54a is catch pin head 54b, the diameter of which is larger than at other locations on the pin.Return spring 56, made from a coil spring, is installed between plunger 54 and fixed core 55, plunger 54 being energized toward the narrowed section 53a end of coil tube 53 by the spring force of return spring 54.

The ends in the direction of travel of plunger 54 are formed with a smaller diameter than the intermediate section, one end being spring receiver 54c which is inserted into return spring 56, and the other end formed to be inserted into the narrowed section 53b of coil tube 53, the intermediate section being formed with a diameter that is larger than that of the narrowed section. In other words, pull-out stopper step 54d is formed on plunger 54, between the large diameter section and the small diameter section with catch pin 54a on it, and plunger 54 is prevented from falling out by the fact that pull-out stopper 54d is retained by a step formed on the inner circumference of coil tube 53 between the intermediate section and narrowed section 53b.

Fixed core 55 is formed such that its end near the axial end of coil tube 53 near plunger 53, which has a smaller diameter than other locations, becomes spring receiver 55a, which is inserted into return spring 56, and outer collar member 55b, which has a larger diameter than other locations, is formed on the other end. Coupler 55c is mounted at the center of said other end. When fixed core 55 is inserted into the flange 53a end of coil tube 53, outer collar member 55b contacts the end surface of coil tube 53, and coupler 55c protrudes from the end of coil tube 53. Also, push pressure pin 57 protrudes from coil tube 53 due to its being inserted through insert opening 55d, which passes through fixed core 55 in the axial direction.

The core formed by installing plunger 54, fixed core 55, and return spring 56 in coil tube 53 is installed in yoke 52 by inserting narrowed section 53b of coil tube 53 into retainer groove 52d provided in side member 52a of yoke 52, and by inserting coupler 55c of fixed core 55 into retainer groove 52e of side member 52b. Here, with the flange 53a of coil tube 53 being disposed between coil 51 and side member 52b of yoke 52, insulation between coil 51 and side member 52b of yoke 52 is assured. Moreover, because coupler 55c is inserted in retainer groove 52e provided in side member 52b of yoke 52, and outer collar 55b is sandwiched between flange 53a of coil tube 53 and side member 52b, fixed core 55 is magnetically coupled to yoke 52.

Electromagnetic release apparatus 50 is secured in position on body 10 by inserting retainer tabs 1 7a and 1 7b mounted on the inner surface of body 1 0a into retainer grooves 52d and 52e provided in yoke 52. In addition, yoke 52 is secured to body 10a by fitting side prtions of yoke 52 into yoke 52 installation grooves 18 formed on the inner surface of body 10a. With yoke secured to body 10a, narrowed section 53b of coil tube 53 and coupler 55c of fixed core 55 are supported between the inner peripheries of retainer grooves 52d and 52e, and the outer edges of retainer tabs 1 7a and 17b, and coil tube 53 is fixed in position with respect to yoke 52.

In an electromagnetic release apparatus 50 constituted as described above, if current flows through coil 5 1, a pulling force will be created between fixed core 55 and plunger 54 so as to reduce the reluctance of the magnetic path through fixed core 55, yoke 52, and plunger 54, and if the current flowing in coil 51 is excessive in the event of a shorted load and the like plunger 54 will move toward fixed core 55 against the spring force of return spring 56. Accordingly, during such operation, the closed breaker contacts 30x can be forcibly opened by operating drive mechanism 40, drive mechanism 40 being connected as described below.

The leading end of catch pin 54a provided on plunger 54 is inserted through catch opening 33e formed at a location between shaft openings 33a of movable contact 33 and movable contact point 32.

When plunger 54 is drawn toward fixed core 55 as a result of magnetic excitation of coil 51, catch pin head 54b on the leading end of catch pin 54a catches on the rim of catch opening 33e, pulling movable contact 33 away from fixed contact 31. Catch opening 33e is formed as an oblong hole connecting a stop hole having a diameter smaller than that of catch pin head 54b, and a guide hole having a diameter larger than that of catch pin head 54b. This configuration allows electromagnetic release apparatus 50 to easily be linked to movable contact 33 during assembly by guiding catch pin 54a into the stop hole after catch pin head 54b has been passed through the guide hole.Moreover, the tip of push pressure pin 57 (left end as shown in Fig. 3), which is attached to plunger 54, is positioned facing second push pressure member 44c of trip plate 44 such that trip plate 44 will be rotated around shaft pin 47 in the clockwise direction (as viewed in Fig. 3) when plunger 54 is drawn into motion by fixed core 55.

On the other hand, thermal release apparatus 60 is furnished with bimetal [bar] 61. One end of bimetal [bar] 61 is attached to terminal bar 21 box, and the other end has adjustment screw 62.

Adjustment screw 62 is in threaded engagement with bimetal and faces first push pressure member 44b of trip plate 44, positioned such that when bimetal [bar] 61 bends due to excessive current flowing in the main electrical path, the tip of adjustment screw 62 pressing against trip plate 44 causes trip plate 44 to rotate around shaft pin 47 in the clockwise direction (as seen in Fig. 3).

Adjustment window 63 is provided in an outer periphery wall of voltage-electrode side of housing 10 near adjustment screw 62 on bimetal [bar] 61. Adjustment window 63 is furnished at the upper end with insertion section 63a formed with a width greater than that of the other parts. The upper edge of adjustment window 63 forms guide surface 63b, which slants downward toward the inside of housing 10.

Installation channels 63c are formed on both side surfaces of adjustment window 63, connected to insertion section 63a at their top ends, and extending to the bottom of adjustment window 63 at their lower ends. In other words, guide ribs 63d extending to the lower end of adjustment window 63, except for insertion section 63a, are formed on both sides of adjustment window 63 at the outside surface of housing 10, and guide ribs 63e extending the full length of adjustment window 63 from top to bottom are formed on the inside surface of housing 10, thus forming installation channels 63c between guide ribs 63d and 63e.

The degree to which bimetal [bar] 61 bends from the electrical current passing through it (its operating sensitivity) depends on variations in the composition of the material used and the location at which connecting wire 38x is connected. Therefore, in order to eliminate variations in the operating sensitivity of drive mechanism 40 (i.e., the current flowing in the main electrical path when drive mechanism 40 operates), it is necessary to adjust the amount adjustment screw 62, which is threaded into bimetal [bar] 61, protrudes from bimetal [bar] 61 on the trip plate 44 side. Accordingly, after assembly, adjustment screw 62 is operated with adjustment window 63 open.On the other hand, since once adjustment screw 62 has been adjusted, there is no need to make any further adjustments to adjustment screw 62, closure plate 64, which is flexible, is dropped into installation channel 63c through insertion section 63a, so that adjustment window 63 will be closed by closure plate 64 to prevent adjustment screw 62's being inadvertently operated, and to prevent foreign matter from entering housing 10. Closure plate 64 is set to be generally equal to the width of adjustment window 63 (the distance between the bottoms of installation channels 63c), and generally equal to the height dimension from top to bottom of adjustment window 63.

When such a closure plate 64 is inserted into adjustment window 63, the upper edge of closure plate 64 hits the upper edge of adjustment window 63, and closure plate 64 cannot be removed.

Terminal plate 21ax, which is part of line terminal 20ax, has a fixed contact plate 39x which is bent downward at a point inside of housing 10. Fixed contact 3 lox is attached at the lower end of fixed contact plate 39x. Facing fixed contact point 31x is movable contact point 32x, which is on movable contact 33x. A portion of arc runner 71, which is made of conductive sheet material, is lapped on the surface to which fixed contact point 31x is mounted, below fixed contact point 31x on fixed terminal plate 39x. Arc runner 71 is furnished with vertically oriented guide member 7 lea which overlaps a portion of fixed contact plate 39x.The lower end of guide member 7 lea continues through inclined member 71b, which slants downward at an angle, to arc suppresser member 71 c, which extends along the bottom wall of housing 10 to a point below base member 52c of yoke 52. Here, arc suppresser grid 72 is disposed between locations on base member 52c of yoke 52 and arc suppresser member 71 c that face each other. Arc suppresser grid 72 has a configuration wherein a plurality of arc suppresser plates 74, made of electrically conductive sheets, are supported generally parallel to each other on the inside of support bracket 73, which is made of an insulating material, generally U-shaped.

Formed in each arc suppresser plate 74 is a cutout 74a into which the lower end of movable contact 33 is received. This arc suppresser grid 72 is disposed such than arc suppresser plates 74 are generally parallel to base member 52b of yoke 52 and arc suppresser member 71 c of arc runner 71. The shape of arc suppresser member 71 c of arc runner 71 is formed such that its width increases in steps as the distance away from inclined member 71b increases.

If movable contact 32 separates from fixed contact 31 and an arc is created, then due to the surrounding magnetic field created as a result of the current flowing through terminal plate 21 ax and movable contact 33x, and due to the magnetic force generated by the arc current, the arc will travel downward in Fig. 3, one end of the arc running along arc runner 71 toward arc suppresser grid 72. In other words, since fixed contact plate 39x on terminal plate 21a faces movable contact 33x, and since the currents flowing in fixed contact plate 39x and movable contact 33x are flowing in opposite directions, an electromagnetic force will act upon the arc in a direction so as to pull it away from fixed contact plate 39x and movable contact 33x.As a result, the fixed contact plate 39x end of the arc will run along arc runner 71 and be guided to arc suppresser grid 72. Since arc runner 33d is formed on movable contact 33x, the other end of the arc will run toward the tip of arc runner 33d. In this manner, the arc is gradually guided to arc suppresser grid 72 while being stretched out in the process.

However, a portion of connecting wire 37x, which connects movable contact 33x to one end of coil 51, is welded to side member 52a of yoke 52 closer to the breaker contacts 30x. Therefore, when one end of the arc runs along arc runner 71, being guided to arc suppresser grid 72, the other end of the arc moves from arc runner member 33d of movable contact 33x to base member 52c of yoke causing a current to flow in a path going through base member 52c of yoke 52, side member 52a of yoke 52, connecting wire 37x, and coil 51. Because the direction of the current flowing in this path is opposite to that in arc runner 71, the magnetic field generated by the currents flowing in base member 52c of yoke 52 and in arc runner 71 is such that the arc receives an electromagnetic force guiding it into arc suppresser grid 72.

In other words, intermediate member 52b of yoke 52 is capable of dual functions: it forms a magnetic path in electromagnetic release apparatus 50, and it also functions with arc runner 71 to suppress arcs. Thus the parts count is reduced in comparison to configurations where a pair of arc runners is provided, thereby simplifying structure and reducing cost.

As shown in Fig. 1 and Fig. 2, movable contactor 33y is connected electrically, through jumper line 38y, which is made of braided wire, to terminal plate 21by, which makes up fixed-side terminal 20by, arranged within the ground-electrode-side compartment.

Jumper line 38y possesses an insulation covering, and serves the function of the primary side of zero-phase current transformer 92 by passing through toroidal core 91. As shown in Fig. 7, jumper line 38x possessing an insulation covering comes from the voltage-electrode side and enters through passage-hole 19a to also pass through toroidal core 91, and both ends of the secondary coil wound about toroidal core 91 are connected electrically to electrical leakage sensing circuit 90 (see Fig. 7). Here, canopy 19b protrudes from the upper rim of passage-hole 19a so as to prevent jumper line 38x, which passes through passage-hole 19a, or the like from interfering with the regions disposed above passage-hole 19a.Electrical leakage sensing circuit 90 is powered from fixed-side terminals 20bx and 20by, and flow of a current at the secondary coil greater than a specified value causes electromagnet mechanism 100 to be energized, there being a leak current or a ground fault current. By virtue of the constitution described below, electromagnet mechanism 100 causes ganged operation of drive mechanism 40, which is arranged at the voltageelectrode side. Energizing electromagnet mechanism 100 results in operation of drive mechanism 40, causing opening of contacts 30x and 30y. As long as there is no electrical leakage, the current flowing through jumper line 38x is equal to the current flowing through jumper line 38y, so the magnetic fields surrounding both jumper lines 38x and 38y cancel each other out, and no current flows through the secondary coil of zero-phase current transformer 92.Emergence of electrical leakage, however, causes the currents flowing in jumper lines 38x and 38y to become unbalanced, and current flows in the secondary coil of zero-phase current transformer 92. When this current is sensed at electrical leakage sensing circuit 90, electromagnet mechanism 100 is energized.

Test switch 93 is connected, through jumper lines 94a and 94b (see Figs. 7 and 9), between both fixed-side terminals 20bx and 20by.

Jumper line 94a, which runs between fixed-side terminal 20bx and test switch 93, also passes through toroidal core 91. Accordingly, when test switch 93 is turned ON, current flows through the secondary coil of zero-phase current transformer 92 and electromagnet mechanism 100 is energized, thereby allowing confirmation of operation of electrical leakage sensing circuit 90. The circuit components making up electrical leakage sensing circuit 90 are mounted on printed circuit board 95, which is arranged at the base of the ground-electrode-side compartment. This printed circuit board 95 is positioned by insertion in retaining groove 111 (see Fig. 9), provided at the inside peripheral surface of body 10a and cover 1 Oby.

Electromagnet mechanism 100 is equipped with yoke 102, formed from a magnetic body in roughly an inverted "U" shape, with the opening at the bottom, and coil 101 is housed within the interior space of yoke 102. Yoke 102 is equipped with a pair of opposing side members 102a and 102b, respectively located at the surfaces at either end of the axial direction of coil 101, and with intermediate member 102c, which passes above coil 101 and which joins the space between the two side members 102a and 102b. Through-hole 102d is formed at the central region of one of the side members 102a.This yoke 102 is held in place by housing 10 by virtue of the fact that it is sandwiched between body 1 0a and cover 1 Oby, while a portion of side member 102b and central member 102c is press-fit into assembly groove 112 provided at the inside peripheral surface of body 1 0a. A pair of bearing members 1 02e is formed at the top and bottom of side member 102a, and shaft 1 03a of ganging lever 103 is mounted so as to intervene between the two bearing members 102e. Axis pin 104 is inserted through bearing holes 1 02f formed in both bearing members 102e, and through shaft 1 03a of ganging lever 103, to retain ganging lever 103 such that it is free to rotate relative to electromagnet mechanism 100.

Coil 101 is wound around the outside peripheral surface of coil cylinder 105, which is made from insulating material. Flanges 105a are integrally formed at either end of coil cylinder 105, and plunger 106, made from a magnetic body, is inserted within the interior cavity of coil cylinder 105 such that it is free to move in the axial direction of coil cylinder 105, with one end passing through-hole 102d. Plunger 106 is formed in such fashion that it is integrally equipped with plunger main body 106a, which is inserted within coil cylinder 105.Latching pin 106b, which protrudes from the surface of one end of plunger main body 1 06a and which is formed with a diameter smaller than that of plunger main body 106a, and with latching head 106c, which is the tip of latching pin 1 06b and which is formed with a diameter larger than that of latching pin 106b. The region between plunger main body 106a and latching head 1 06c of latching pin 1 06b is inserted within latching slit 103b provided on ganging lever 103. Here, plunger 106 inserts latching pin 106b within latching slit 103b of ganging lever 103, and since the diameters of both plunger main body 1 06a and latching head 106c are greater than the width of latching slit 103b, plunger 106 will not fall out of ganging lever 103.

Ganging lever 103 straddles shaft 103a, and is equipped with thrust member 103c at the side opposite to the aforesaid latching slit 103b. Thrust member 103c passes through passage-hole 19c formed above passage-hole 19a to enter the voltage-electrode side, where it opposes adjustment screw 62 provided on bimetallic plate 61 as well as the first thrust member 44b of trip plate 44. By pressing on trip plate 44 in the same manner as bimetallic plate 61, ganging lever 103 can cause drive mechanism 40 to operate. Thrust projection 103d, to be described below, protrudes above the region wherein latching slit 103b is formed on ganging lever 103.

Now, as was the case with the voltage-electrode side, a movable contactor 33y is arranged within the ground-electrode-side compartment. Movable contact 32y provided at one end of movable contactor 33y, together with fixed contact 30y provided on movableside terminal 20ay, makes up contacts 30y. Movable contactor 33y is retained by movable member 121, which is formed from insulating synthetic resin. Movable member 121 pivots about pivot pin 122, which is supported between body 1 0a and cover 1 Oby, such that its top end in Fig. 1 rotates freely. The tip of foot member 48b of contactor link 48, which passes through guide hole 16 (see Fig. 3) provided in body 1 0a to enter the ground-electrode side from the voltage-electrode side, is inserted within the bottom end of movable member 121.

Accordingly, movement of foot member 48b of contactor link 48 within the range allowed by guide hole 16 is accompanied by swiveling of movable member 121 with pivot pin 122 as center of rotation.

Movable contactor 33y is equipped at one end with movable contact 32y, and is equipped at the other end with spring holder member 33by bent into roughly "L" shape. Supporting projection 33f is formed in protruding fashion at the rims at both sides of the region between movable contact 32y and spring holder member 33by. One end of contact-opening spring 34y, which is made from a coil spring, is elastically mounted to spring holder member 33by, and the other end of contact-opening spring 34y is housed within spring holder recess 35y formed at the inside surface of body 1 Oa.

Movable member 121 is formed so as to be frame-shaped, such that a pair of side frames 121 a are coupled between their top ends by upper frame 121 b in continuous and integrated fashion, and are coupled between their lower ends by lower frame 121 c in continuous and integrated fashion. Bearing hole 121d, through which pivot pin 122 is inserted, is formed in upper frame 121b; bearing hole 121f, into which foot member 48b of contactor link 48 is inserted, is formed in lower frame 121c.Movable member 121 retains movable contactor 33y as a consequence of spring holder member 33by inserted between upper frame 121b and lower frame 121 c of movable member 121, along with the abutment of restraint member 121 g, which extends below lower frame 121 c of movable member 121 at a surface protruding from movable contact 32y below supporting projection 33f. Further, retaining groove 121h, into which supporting projection 33f of movable contactor 33y is inserted, is also formed on movable member 121. Of the peripheral surfaces of lower frame 121 c of movable member 121, those regions that make contact with movable contactor 33y are formed with arc-shaped cross-sections.Accordingly, movable contactor 33y is capable of swiveling motion relative to movable member 121, and, with movable contact 32y directed so as to approach fixed contact 31y, positioning is accomplished by restraint member 121g. The aforementioned jumper line 37y passes between upper frame 121b and lower frame 121 c of movable member 121, and is connected to spring holder member 33by of movable contactor 33y. Positioning projection 121 i protrudes in continuous and integrated fashion from upper frame 121b of movable member 121. The function of positioning projection 121i is described below.

Lifter projection 12 1j protrudes from voltage-electrode-side side frame 121a at movable member 121 along a line drawn from lower frame 121c. Pusher member 13 la, being one side of roughly L-shaped engaging lever 131, which pivots about pivot projection 113 (see Fig.

9) protruding from the inside surface of the ground-electrode side of body 10a, rests on this lifter projection 121j. Engaging member 131b, which is another member of engaging lever 131, sandwiches return spring 132, which is formed from a coil spring, in the space between it and spring seat 114 provided on the inside surface of the groundelectrode side of body 1 0a. Spring holder recess 11 4a, into which one end of return spring 132 is inserted, is formed on spring seat 114.

Engaging notch 131 c is formed at the tip of engaging member 131 b of engaging lever 13 1.

Indicator 133, retained so as to slide freely in slide groove 115 (see Fig. 9) formed on the inside peripheral surface of body 1 0a and cover 1 Oby, is arranged above engaging member 131 b of engaging lever 131. Indicator 133 retains push spring 134, which is formed from a coil spring, in the space between it and the inside surface of body 10a, and is energized to the left in Fig. 9 by push spring 134. Thrust projection 133a, which is pressed upon by the upper end of thrust projection 1 03d provided on ganging lever 103, and engaging projection 133b, which is capable of being latched by engaging notch 131 c of engaging lever 131 protrude from the lower surface of indicator 133. In addition, indicator area 133c, inscribed with text and colored differently from other regions, is formed at the upper surface of indicator 133.Indicator window 135, made from a transparent plate, is mounted above indicator 133 in housing 10. Indicator 133 slides between an indicating position where indicator area 1 33c lines up with indicator window 135, and a non-indicating position where indicator area 133c is not visible through indicator window 135.

Engaging lever 131 positions engaging member 131 b such that it occupies a position lower than engaging projection 133b of indicator 133 when movable member 121 is positioned such that movable contact 32y is positioned so as to contact fixed contact 31y. Engaging notch 131 c is positioned at a location that allows it to be latched by engaging projection 133b as a result of lifting of engaging member 13 it by the restoring force of return spring 132 when movable member 121 is positioned at a location such that movable contact 32y disengages from fixed contact 3 liy. Thrust projection 103d of ganging lever 103 causes indicator 133 to slide, against the restoring force of push spring 134, toward the indicating position by pressing on thrust projection 133a of indicator 133 in accompaniment to the movement of plunger 106 during operation of electromagnet mechanism 100. Thus, if movable contact 32y is not engaged with fixed contact 31y when indicator 133 slides against the restoring force of push spring 134, engaging projection 133b will be latched by engaging notch 131c, and indicator 133 will be retained at a position such as will cause push spring 134 to be compressed. This position being the indicating position, indicator area 133c will be visible through indicator window 135.

Now, test switch 93 comprises a pair of contactor plates 141 and 142, and push button 143, which is mounted on housing 10 so as to allow it to exert pressure on movable member 142a, which is provided on one of the contactor plates 142 and which possesses plasticity.

Retaining projection 141 a protrudes from the side rim of contactor plate 141, and contactor plate 141 is fixed in place on housing 10 by virtue of the fact that this retaining projection 141a is press-fit into a retaining hole (not shown) provided on protruding platform 116, which protrudes from the inside surface of the ground-electrode side of body 1 0a. Contactor plate 141 is arranged vertically, its top rim being positioned below movable plate 142a of contactor plate 142.

Contactor plate 142 possesses movable plate 142a and fixed plate 142b, and is formed such that movable plate 142a and fixed plate 142b are fashioned so as to be integrally continuous by virtue of bridging plate 142c at the fixed-end side of movable plate 142a.

Bridging plate 142c possesses a curved shape that is convex above, and contactor plate 142 is fastened to housing 10 by press-fitting bridging plate 142c into retaining hole 117 provided on body 10a. Fixed plate 1 42b mounts on mounting platform 118, which protrudes from the inside surface of the ground-electrode side of body 1 Oa. Jumper line 94b, which is connected at one end to electrical leakage sensing circuit 90, is connected to terminal member 142d, which protrudes from the side rim of fixed plate 142b. In addition, positioning projection 121i, provided on movable member 121, is located below movable plate 142a.

The tip of positioning projection 121i is positioned below the top edge of contactor plate 141 when movable contact 32y is in contact with fixed contact 3 ly, and is positioned above the upper rim of contactor plate 141 when movable contact 32y disengages from fixed contact 3 ly.

Push button 143 is equipped at its lower surface with pushing projection 143a, and the lower end of pushing projection 143a abuts the upper surface of movable plate 142a. Here, the region on movable plate 142a that opposes the aforementioned positioning projection 121i is located between the region that bears the pressure from pushing projection 143a and the region where movable plate 142a contacts contactor plate 141. Accordingly, if pressure is exerted on push button 143 when movable contact 32y is in contact with fixed contact 31y, then movable plate 1 42a can be made to contact contactor plate 141, turning test switch 93 ON.Furthermore, when movable contact 32y is not engaged with fixed contact 3 ly, downward movement of movable plate 142a is impeded by positioning projection 121i even if pressure is exerted on push button 143, and movable plate 142a cannot contact contactor plate 141. Push button 143 is housed within button housing recess 119 provided on the upper surface of housing 10, and is prevented from falling out of housing 10 by virtue of the fact that steps 143b formed at the ends on both sides of push button 143 are engaged by stop member 1 19a, which protrudes from the edge of the opening of button housing recess 119.

Movable-side terminals 20ax and 20ay, and fixed-side terminals 20bx and 20by, are respectively equipped with terminal brackets 22, formed in roughly square-shaped cross-section by bending sheet metal possessing electrical conductivity; anchor screws 23, screwed into the upper members of terminal brackets 22; and terminal plates 2 lax, 21ay, 21 box, and 21by, abutting the lower ends of anchor screws 23. Terminal brackets 22 are housed, so as to permit movement vertically, within terminal housing chambers 24ax, 24ay, 24bx, and 24by, which have corniform cross-sections as viewed from above and which are formed in housing 10. Thus, the heights of terminal housing chambers 24ax, 24ay, 24bx, and 24by are greater than those of terminal brackets 22, and, as terminal brackets 22 are held around their girths by terminal housing chambers 24ax, 24ay, 24bx, and 24by, movement is permitted in the vertical direction only. The heads of anchor screws 23 are formed in the shapes of truncated cones having smaller diameters at their upper parts than at their lower parts, and threaded actuation holes 25, possessing diameters of a size such that the heads of anchor screws 23 can be partially inserted therein but such that the heads of anchor screws 23 will not slip through, are formed in the upper walls of terminal housing chambers 24ax, 24ay, 24bx, and 24by.The diameters of the upper parts of threaded actuation holes 25 are designed such that they are smaller than the tops of the heads of anchor screws 23, while the diameters of the bottoms of threaded actuation holes 25 are designed such that they are larger than the bottoms of the heads of anchor screws 23. The tips of terminal plates 21ax, 21ay, 21bx, and 21by are exposed beyond the outside surface of housing 10 and are bent upward. Vertical movement of the tips of terminal plates 21ax, 21ay, 21 bx, and 21 by is prohibited by virtue of engagement of securing projections 21c, formed at the tips of terminal plates 21 ax, 21 ay, 21bx, and 21 by, with securing groove 26, formed on the outside surface of housing 10.In addition, terminal plate retaining grooves 27, which position terminal plates 21 ax, 21 ay, 21 bx, and 21 by, are formed on the side walls of terminal housing chambers 24ax, 24ay, 24bx, and 24by, which partition terminal housing chambers 24 at, 24ay, 24bx, and 24by from the interior of housing 10. Vertical movement of terminal plates 21ax, 21ay, 21bx, and 21by is also prohibited by virtue of the fact that terminal plates 21ax, 21ay, 21bx, and 21by are partially inserted within terminal plate retaining grooves 27.Because vertical movement of terminal plates 21ax, 21ay, 21bx, and 21by is prohibited to either side of the regions abutting anchor screws 23, terminal plates 21ax, 21 ay, 21bx, and 21by will be held in place despite the action of an external force from anchor screws 23. The distance between terminal plates 21ax, 2iay, 21 box, and 21by, and the top walls of terminal housirlg chambers 24ax, 24ay, 24bx, and 24by is designed to be roughly the same as the length of anchor screws 23.

Now, if the tip of a flat head screwdriver or the like is inserted within threaded actuation holes 25 and anchor screws 23 are rotated, then, depending on the direction of rotation of anchor screws 23, terminal brackets 22 will move up or down, thereby permitting the distance between the lower members of terminal brackets 22 and terminal plates 21ax, 21ay, 21bx, and 21by to be varied.Thus, by inserting an electrical wiring member such as an electric lead or a bus bar at connecting through-hole 28 provided in the peripheral wall of housing 10 in correspondence to the regions between the bottom walls of terminal housing chambers 24ax, 24ay, 24bx, and 24by and terminal plates 21ax, 21ay, 21bx, and 21by, and rotating anchor screws 23 so as to cause the lower members of terminal brackets 22 to approach terminal plates 21ax, 21ay, 21bx, and 21by, the electrical wiring member is sandwiched between terminal brackets 22 and terminal plates 21ax, 21ay, 21bx, and 21by, thereby permitting electrical connection with the electrical wiring member.

An attachment mechanism, for fastening so as to allow free attachment and removal with respect to an attachment rail (so-called DIN rail) 80 (see Fig. 5), arranged within a distribution panel interior or the like, is provided on the lower surface of housing 10. Attachment rail 80 possesses a shape such that collars 80a protrude integrally and face outward along the full length of the tip edges of both foot members of a rail main body formed in roughly C-shaped cross-section.

Attachment groove 81 is formed at the lower surface of housing 10 such that it runs in a direction orthogonal to a direction connecting movable-side terminals 20ax and 20ay and fixed-side terminals 20bx and 20by. Engaging projection 82 protrudes from one of the side walls of attachment groove 81, one of the collars 80a of attachment rail 80 being inserted therein between it and the inside base surface of attachment groove 81. Housing groove 83, which passes through the outside surface of housing 10, is formed at the other side surface of attachment groove 81, and slider 84 is installed within this housing groove 83.

Slider 84, as shown in Fig. 3, is formed in continuous and integrated fashion from a synthetic resin in a shape such that it is equipped with actuator 84a, protruding at one end from the outside surface of housing 10, coupling member 84b, extending from actuator 84a in the direction of the center line of housing groove 83, pawl 84c, provided integrally at the tip of coupling member 84b and protruding into attachment groove 81, and a pair of deflecting members 84d, extending integrally from actuator 84a parallel to coupling member 84b at either side of coupling member 84b. Positioning projections 84e respectively protrude, so as to be directed away from coupling member 84b, from the tips of each deflecting member 84d. In addition, Vshaped grooves 84f are formed at the tip surfaces of positioning projections 84e.

Though not shown in the figures, positioning projections 84e are inserted within the inside surfaces of housing groove 83, and a movement restricting recess, the width of which in the direction of the center line of housing groove 83 is longer than positioning projection 84e, is formed such that slider 84 is capable of sliding within the range allowed by this movement restricting recess. A peaked projection is formed on the inside peripheral surface of the movement-restricting recess, and engages with V-shaped groove 84f in such manner that pawl 84c of slider 84 is made to protrude into attachment groove 81, and collar 80a of attachment rail 80 is retained between the inside base surface of attachment groove 81 and pawl 84c.

As a result of the aforesaid constitution, after one of collars 80a of attachment rail 80 is inserted between the inside base surface of attachment groove 81 and engaging projection 82 forcing slider 84 into housing 10 in such manner that the other collar 80a is made to abut the inside base surface of attachment groove 81, the other collar 80a of attachment rail 80 is caused to be retained between the inside base surface of attachment groove 81 and pawl 84c. In this way, housing 10 can be secured relative to attachment rail 80. In this position, the peaked projection engages V-shaped groove 84f, and movement of slider 84 is prohibited.

To detach housing 10 from attachment rail 80, if the tip of a flat head screwdriver or the like is inserted in access hole 84g provided on actuator 84a, which protrudes at the side surface of housing 10, and slider 84 is pulled away from housing 10, then pawl 84c, engaged with respect to collar 80a of attachment rail 80, will be released and will allow detachment of housing 10 from attachment rail 80.

Next, circuit breaker operation will be described. Fig. 8 shows the circuit breaker in the "on" state (contacts closed) of the breaker contacts 30x at voltage-electrode side, operation member 41a of actuation handle 41 thrown around handle shaft 42 to the right. At this time, trip plate 44 is energized counterclockwise (as viewed in Fig. 8) around shaft pin 47 by the spring force of handle return spring 43, thus holding first push pressure member 44b to oppose against adjustment screw 62 in bimetal [bar] 61.Moreover, the spring force of contact spring 34x is being applied via movable contact 33x and contact link 48 to latch plate 46, and, because the distance between leg 48a of contact link 48 and shaft tabs 41d on actuation actuation handle 41 is regulated by handle link 45, latch plate 46 receives the spring force of contact pressure spring 34x such as to energize it in the counterclockwise direction with handle shaft 42 as the center of rotation. Accordingly, stop plate 46a of latch plate 46 is engaged in hook notch 44e in arm 44d of trip plate 44. In other words, the state shown in Fig. 8 is maintained because although latch plate 46 is trying to rotate to the right, it is being prevented from doing so by latch plate 46.In this state, latch plate 46 is held in position by shaft handle 42 and trip plate 44, and handle link 45 and contact link 48 are also fixed in their proper positions. As a result, movable contact 33 is energized in the counterclockwise direction, centered around leg member 48b of contact link 48, by the spring force of contact pressure spring 34x, and movable contact 32x is contacting fixed contact 3 1 x with a pressure corresponding to the spring force of contact pressure spring 34x. In this state, the position relationship of stopper 36, provided on the inside surface of housing 10, is set so that it will not touch spring receiver member 33bx of movable contact 33.

On the ground-electrode side, when voltage-electrode-side contacts 30x are in a closed state, foot member 48b of contactor link 48 is positioned at the left end of guide hole 16, movable contactor 33y is pressed leftward by movable member 121, and movable contact 32y comes in contact with fixed contact 3 liy, as shown in Fig. 9. At this point, bearing a restoring force from contact-opening spring 34y, the lower end of movable contactor 33y is energized leftward in Fig. 9.

Contact-opening spring 34y causes a contact pressure to be exerted between contacts 30y. Thus, when voltage-electrode-side contacts 30x are closed, ground-electrode-side contacts 30y will also close.

If, on the other hand, operation member 41a of actuation handle 41 is thrown around handle shaft 42 to the left, as shown in Fig. 10, breaker contacts 30x of the circuit breaker will be in the "off" state (contacts open). In other words, rotating actuation handle 41 around handle shaft 42 to the left moves the upper end of handle link 45 to the right, pulling leg member 48a of contact link 48 upward. When the location of shaft tabs 41 d shifts to the right, relative to a line drawn between handle shaft 42 and leg member 48a, the spring force of contact pressure spring 34x being applied to handle link 45, through movable contact 33x and contact link 48, will act to move actuation handle 41 further to the left, causing leg member 48b of contact link 48 to move to the left along guide channel 16.Moving leg member 48b of contact link 48 to the left in this manner results in spring receiver member 33b of movable contact 33x being pressed, by the spring force of contact pressure spring 34x, against stopper 36, provided on the inside peripheral surface of housing 10. Here, since the spring force of contact pressure spring 34x is acting upon a point below the lower end of stopper 36, movable contact 33 is energized in the clockwise direction, and movable contact point 32 is separated from fixed contact 3 1. In the open state of the breaker contacts 30x, latch plate 46, regulated by handle link 45 and leg member 48a of contact link 48, turns counter-clockwise with handle shaft 42 as its center of rotation, and is disengaged from trip plate 44.

When contacts 30x are opened by the actuation of actuation handle 41, then, at the ground-electrode side, movement of foot member 48b of contactor link 48 to the right end of guide hole 16 causes the lower end of movable member 121 to move right, as shown in Fig. 11. Accordingly, the lower end of movable contactor 33y also moves right, and movable contact 32y disengages from fixed contact 31y. Here, contact-opening spring 34y energizes movable contactor 33y clockwise in Fig. 11 about the region in contact with lower frame 121 c of movable member 121, but the movement of movable contactor 33y is restricted by restraint member 121g provided on movable member 121, and movable contact 32y does not come in contact with fixed contact 3 liy.

Now, from the closed-contact state shown in Fig. 8 and Fig. 9, if an overload state occurs and excessive current flows in bimetallic element 61, causing bimetallic element 61 to bend, then first thrust member 44b of trip plate 44 will be pressed by adjustment screw 62, which is threaded to bimetallic element 61. Further, if a short or the like at the overload side causes excessive current flow at coil 51 and movable core 54 is sucked toward fixed core 55, then second thrust member 44c of trip plate 44 will be pressed by thrust pin 57, which bears the force from movable core 54.Alternatively, if electrical leakage occurs at the overload side, then current flows in the secondary coil of zero-phase current transformer 92, causing electromagnet mechanism 100 to be energized through electrical leakage sensing circuit 90, and, because ganging lever 103 rotates around pivot pin 104 as a result of plunger 106 being retracted into coil 101, first thrust member 44b is pressed upon by thrust member 103c of ganging lever 103, as shown by the broken line in Fig. 14. In either case, trip plate 44 will rotate clockwise about pivot pin 47, as shown in Fig. 12.

Rotation of trip plate 44 clockwise at Fig. 12 causes its engagement with latch plate 46 to be released, and from the closedcontact state, because latch plate 46 bears the restoring force of contact-opening spring 34x and rotates clockwise about handle shaft 42, the lower end of latch plate 46 moves left. The foregoing occurs from the closed-contact state, because foot member 48b of contactor link 48, formerly the center of rotation of movable contactor 33x, moves left in Fig. 12 along guide hole 16, movable contactor 33x is pressed against stopper 36 by the restoring force of contact-opening spring 34x, as in the open-contact state shown in Fig. 10, and movable contact 32x disengages from fixed contact 31 x, thereby assuming the open-contact state. In other words, if excessive current flows through the main current path, then rotation of trip plate 44 causes its engagement with latch plate 46 to be released, and discharge of the force that had been acting on latch plate 46 causes so-called tripping action to occur, thereby opening contacts 30x. Because disengagement of trip plate 44 from latch plate 46 and opening of contacts 30x as a result of the tripping action allows actuation handle 41 to rotate freely around handle shaft 42, the restoring force of handle return spring 43 causes actuation handle 41 to return to the OFF position (the position at Fig.

10). Furthermore, because at this time opening of contacts 30x causes electromagnetic release mechanism 50, thermal release mechanism 60, and electromagnet mechanism 100 to all return to their original states, the state immediately following tripping action returns to the same state that exists when actuation handle 41 is actuated to the OFF position.

If contacts 30x open under tripping action, then, at the groundelectrode side, as shown in Fig. 13, movement of foot member 48b of contactor link 48 causes movable member 121 to move, and movable contact 32y to be drawn away from fixed contact 31y, in the same fashion as when contacts 30x are opened by actuation handle 41. In short, if tripping action causes voltage-electrode-side contacts 30x to open, contacts 30y will open in ganged fashion at the ground-electrode side.

When contacts 30x and 30y open as a consequence of electrical leakage, however, it would be dangerous to restore them without first eliminating the leaking location. Hence, if contacts 30x and 30y open as a consequence of electrical leakage, retraction of plunger 106 into coil 101 is accompanied by rotation of ganging lever 103, causing thrust projection 133a of indicator 133 to be pushed, against the restoring force of push spring 134, by thrust projection 1 03d provided on ganging lever 103. Indicator 133 slides, and indicator area 133c lines up with indicator window 135.Here, because the lower end of movable member 121 moves right in Fig. 13 so as to cause contacts 30y to open, pusher member 131 a of engaging lever 131 moves down in accompaniment to the movement of lifter projection 12 1j of movable member 121, and the restoring force of return spring 132 causes engaging member 131 b to move upward. As a result, engaging notch 13 Ic of engaging lever 131 is latched by engaging projection 1 33b of indicator 133, and indicator 133 is retained in the indicating position, where indicator area 133c lines up with indicator window 135. Thus, tripping action occurring as a result of electrical leakage is indicated by indicator 133, and that indication state is maintained until contacts 30x and 30y are subsequently closed by actuation of actuation handle 41.

Here, when electrical leakage is not sensed, ganging lever 103 bears, through indicator 133, a restoring force from push spring 134, and keeps plunger 106 in a position such that it protrudes from coil 101. At this time, plunger main body 106a is away from side member 102b of yoke 102. If electrical leakage is sensed, the suction force exerted between side member 1 02b of yoke 102 and plunger main body 1 06a will cause plunger 106 to be retracted into coil 101.

Test switch 93 is provided in order to test the operation of electrical leakage sensing circuit 90. When contacts 30x and 30y are closed, depression of push button 143 causes movable plate 142b of contactor plate 142 to come in contact with contactor plate 141, as shown in Fig. 15, causing current to flow at jumper line 94a and current to flow at the secondary coil of zero-phase current transformer 92, thereby simulating a phenomenon similar to electrical leakage. In order to insure that test switch 93 is always turned OFF following opening of contacts 30x and 30y, movable plate 142a is lifted up by positioning projection 121i provided on movable member 121, as shown in Fig. 13, so that movable plate 142a is incapable of contacting contactor plate 141 despite depression of push button 143.If movable-side terminals 20bx and 20by are assumed to be the power-supply side, throwing the test switch 93 ON results in a short on the power-supply side. After tripping action, test switch 93 is forced OFF by positioning projection 121 i, such that there is no interruption of the shorted state even if push button 143 is held down continuously. In particular, because positioning projection 121i is made to abut movable plate 142a at a location between the location that comes in contact with contactor member 141 and the location acted upon by the pressure from push button 143, if a relative relationship such that the tip of positioning projection 121 i protrudes above the upper end of contactor 141 is maintained during interruption of a main current path, movable plate 1 42a can be definitively drawn away from contactor member 141 even when the pressure from push button 143 is large.

Claims

CLAIMS:

1. A circuit breaker comprising: a pair of first and second fixed contacts; a pair of first and second contactors each of which is formed at its one end with a movable contact engageable with each one of said first and second contacts and is connected at the other end to a contact opening spring to receive therefrom a bias of opening each said movable contacts from the associated fixed contact, each said contactors being linked intermediate its ends to receive an operating force of closing and opening each said movable contacts to and from the associated fixed contact; a handle linked to said first and second contactors for manually closing and opening said movable contacts to and from said fixed contacts;; a drive mechanism releasably linking said handle to said first and second contactors for enabling said handle to open and close said contacts when linked and for allowing said first and second contactors to open said contacts when released; a release mechanism which, in response to sensing an abnormal current flow through a main current path including said closed contacts, releases said linkage between said handle and said first and second contactors; wherein said drive mechanism includes a contactor link having a pin which is inserted to said first contactor at an intermediate portion between said movable contact and said spring for linking said drive mechanism to said first contactor, a cradle being provided to swivel about an axis parallel to the pin of said contactor link, said cradle linked at a portion other than said axis to said contactor link, said cradle being connected to said second contactor at a portion intermediate between said movable contact and said spring such that said movable contact of said second contactor is caused to close and open to and from the fixed contact in accordance with the swiveling movement of said cradle caused by the closing and opening of said movable contact of said first contactor to and from the fixed contact.

2. The circuit breaker as set forth in claim 1, wherein said contactor link is made of a metal and said cradle is made of a plastic material.

3. The circuit breaker as set forth in claim 1, wherein a zero-phase current transformer is provided to sense currents respectively flowing through said fixed contacts and the associated movable contacts, and an electromagnet actuator is provided to release the linkage by said drive mechanism from said handle to said first and second contactors in response to detection of the abnormal current flow through the main current path, and wherein a housing is provided to have two compartments separated by an insulation partition, wherein said first contactor, said handle, and said drive mechanism are accommodated within one of said two compartments, while said second contactor, said zero-phase current transformer, and said electromagnet actuator are accommodated within the other compartment.

4. A circuit breaker which comprises: a zero-phase current transformer having a primary defined by a main current path between a voltage source and a load; an electromagnet actuator which is driven by a secondary output of said zero-phase current transformer developed upon occurrence of unbalanced current flowing through said main current path so as to actuate a drive mechanism in a direction of opening a movable contactor; an indicator plate indicating the actuation of said electromagnet actuator and movable between an actuation-indicating position and a non-indicating position, said indicator being urged by a spring toward said non-indicating position and linked to said electromagnet actuator so as to move toward said actuation-indicating position against the bias of said spring in response to the actuation of said electromagnet actuator; and latch means for latching said indicator plate to said actuationindicating position against the bias of said spring when said indicator plate moves to said actuation-indicating position in response to said drive mechanism driving to open said movable contactor.

5. The circuit breaker as set forth in claim 4, wherein said electromagnet actuator includes a plunger and a lever which is pivotally supported about a pivot axis and which is engaged with said plunger at a portion spaced away from said pivot axis, said indicator plate being linked to said electromagnet actuator by way of said lever.

6. The circuit breaker as set forth in claim 1, further including: a zero-phase current transformer having a primary defined by a main current path between a voltage source and a load; a leakage interrupter which is driven by a secondary output of said zero-phase current transformer developed upon occurrence of unbalanced current flowing through said main current path so as to open a movable contactor for interrupting said main current path; and a test switch for flowing an unbalanced current in a simulative manner through said primary of said zero-phase current transformer, said test switch comprised of a movable plate pushable by a button and a contact plate disposed in an opposite relation to said movable plate so as to form a switch contact with said movable plate; wherein said leakage interrupter including a stopper which projects and presses said movable plate in a direction of disengaging it from said contact plate when said movable contactor is driven to open, said movable plate being engageable with said contact plate at a point which is offset toward a free end of said movable plate from a point of receiving a pressing force from said button, and said stopper being engageable with said movable plate at a point between a point where said movable plate abuts against said contact plate and a point where said movable plate receive the pressing force from said button.

7. A circuit breaker comprising: a first movable contactor coupled to a drive mechanism; a second movable contactor restricted to movement about a predefined axis; and a movable member effective to gang the opening/closing of the second movable contactor to that of the first movable contactor.

8. A circuit breaker substantially as hereinbefore described, with reference to the accompanying drawings.