GB2049289A - Multi-pole line circuit breaker - Google Patents

Abstract

Abutting side walls 17,18 of adjacent circuit-breaker units have recesses 19 accommodating a carrier plate 22 of a coupling element 21 mounted pivotally on a projection 26. Plate 22 has two projections 23,24 on each side extending through apertures 20 in the side walls 17, 18 into the two units. One set of projections 23 on each side are adjacent studs 8 each on a pivotable holder 7 for a pawl 9 of the latch, said pawl being engaged by release lever 1 in the make position. The other projections 24 on the two sides are each situated below a projecting edge 25 of the release lever 1. The release lever 1 of a circuit-breaker unit may be rotated by a magnetic or thermal release system, so that the pawl disengages and, under spring pressure, causes a contact lever 13 and the paw holder 7 to pivot. The stud 8 on the pawl holder 7 strikes against the associated projection 23 and rotates the coupling element 21. Consequently the other projection 24 lifts the release lever 1 of the adjacent circuit breaker unit which is also tripped. <IMAGE>

Description

SPECIFICATION Multi-pole line circuit-breaker This invention relates to a multi-pole line circuitbreaker comprising a plurality of adjacent narrow circuit-breaker units, each having overcurrent tripping means and manual tripping operated by means of a rocker, each unit having a latch in the form of a toggle lever system in a dished housing between the rocker and a contract lever, said latch comprising a release lever and a pawl connected to the contact lever and adapted to engage the release lever, a coupling element mounted to be freely pivotable being provided to transmit tripping between the latches of adjacent circuit-breaker units, said coupling element comprising a carrier plate and drive projections engaging in the latches and extending through apertures in the adjacent side walls of the housings, one set of such projections being associated with the pawls and the others being associated with the release levers of the adjacent circuit-breaker units.

Numerous proposals have been made for coupling an individual protective switch or automatic circuit-breaker to adjacent circuit-breakers of the same type, so that over-current tripping of one of the circuit-breakers associated with a specific phase of the a.c. power supply causes the adjacent circuit breakers associated with the other phases to be tripped automatically and as quickly as possible. It is also known to make the coupling elements for such coupling as simple as possible and fit them to the individual circuit breakers, another requirement being that the basic structure of the individual circuit-breakers should require the minimum modification.

German Patent Specification 15 63 919, for example, discloses a multi-pole circuit-breaker, in which all poles break automatically, a coupling ortransmis- sion element being movable in grooves in the form of gaps or recesses in the side walls of the adjacent individual circuit-breakers, the transmission element having a driver adapted to be actuated by the contact arm of one of the poles while an extension ofa toggle joint or pawl mechanism component of the adjacent individual circuit-breaker is adapted to be actuated by a second driver associated with the transmission member.

German Offenlegungsschrift 26 51 158 discloses a multi-pole circuit-breaker in which each individual circuit-breaker has a transmission shaft with a projection to act on a break lever. Each transmission shaft has 90" offset slots at the ends, and intermedi ate coupling elements engage in said slots byway of projecting plates in orderto connect the transmis sion shafts of adjacent circuit breakers.

German Offenlegungsschrift 21 10 258, in particu lar, discloses a multi-pole automatic circuit breaker with a coupling of the type indicated hereinbefore.

It has been found that the coupling systems of the above protective switches or automatic circuit breakers have various disadvantages. For example, the disadvantage of the circuit-breaker according to German Patent Specification 15 63 919 is that the movable transmission member may tilt and there are also considerable frictional-forces, so that the transmission of the tripping movement is rendered difficult or may even be obstructed. The coupling system according to German Offenlegungsschrift 26 51 158 has numerous complex components which result in the adjacent circuit-breaker breaking only relatively slowly, an additional factor in this case being the coupling play required.The coupling element described in German Offenlegungsschrift 2110 258 occupies additional space inside the circuit-breaker housing, so that considerable structural expense is required to maintain a minimum circuit-breaker width, if this can be achieved at all.

In all the aforementioned known multi-pole protective switches or automatic circuit-breakers, all the coupled individual circuit-breakers break not only when tripping is caused by an overcurrent in one of the phases connected to each of the circuit-breakers, but also when one of the circuit-breakers is disconnected by manual tripping (by actuating a rocker).

Also, if the individual circuit-breakers are provided with a free-trip facility, it is not possible to actuate the circuit-breakers adjacent that circuit-breaker which is exposed to the overcurrent. In many cases; however, it is desirable that the adjacent coupled individual circuit-breakers should be actuated separately in cases where there is no overcurrent to trip the circuit-breaker in question, e.g. to enable a signal contact to be actuated.

An object of this invention is to provide a multipole line circuit-breaker of the kind referred tohereinbefore, in which a simple coupling element movable with little friction can subsequently be installed between adjacent individual circuit breakers without occupying any space in the interior of the circuit-breaker and without any expensive modifications of the individual circuit-breakers.

According to the invention, there is provided a multi-pole line circuit breaker comprising a plurality of adjacent narrow circuit-breaker units, each having overcurrent tripping means and manual tripping operated by means of a rocker, each unit having a latch in the form of a toggle lever system in a dished housing between the rocker and a contact lever, said latch comprising a release lever and a pawl connected to the contact levere and adapted to engage the release lever, a coupling element mounted to be freely pivotable being provided to transmit tripping between the latches of adjacent circuit-breaker units, said coupling element comprising a carrier plate and driver projections engaging in the latches and extending through apertures in the adjacent side walls of the housings, one set of such projections being associated with the pawls and the others being associated with the release levers of the adjacent circuit-breaker units, and wherein the car rier plate for the coupling element is mounted in external recesses in the abutting side walls of the housings, and each of one set of driver projections projecting on either side of the carrier plate of the coupling element is associated with one of two lateral studs on a latch pawl holder in the form of a lever mounted for pivoting coaxially of the pivot of the release lever at one end, said pawl holder bearing the pawl by means of the studs at its other end, the arrangement being such that only when the pawl is disengaged from the release lever, as a result of overcurrent tripping, does the pawl holder pivot about its pivot and pivot the coupling element by way of one of the studs which the associated driving projections abuts, the coupling element in turn acting on the release lever of the adjacent circuitbreaker unit via its other driver projections projecting on either side of the carrier plate.

In the multi-pole circuit-breaker according to the invention, the coupling element occupies no space inside the circuit breaker. In the case of circuitbreaker units with a completely closed housing, only one set of halves of the housing have to be replaced by halves having apertures and recesses for the coupling element. The pivotal mounting of the coupling element can also be obtained by the provision of a projection on one of the halves, without interfering with the switch-breaker mechanism.

Since one of the driver projections is driven with a pivotal movement by part of the circuit breaker unit latch which itself performs a pivoting movement only when the circuit breaker is tripped by overcurrent, but not manually, the individual manual actuation facility of the units is retained. Such unit or single-pole line circuit-breakers are disclosed, for example, in German Offenlegungsschrift 28 30 648.

An embodiment of the invention is described below by way of example with reference to the accompanying drawings in which: Figure 1 is a side view of a circuit-breaker unit, forming part of a multi-pole line circuit breaker embodying the invention in the make position, together with a coupling element, partly in section along the inside of one sidewall of the housing, Figure 2 is a view in vertical section of the coupling element disposed between two abutting side walls of the housings of two adjacent circuit breaker units each of the form shown in Figure 1, Figure 3 is a partial top elevation and partial section of the coupling element disposed between the housing side walls, and Figure 4 is a similar plan view to Figure 1 showing the circuit-breaker unit tripping.

The multi-pole line circuit breaker described below comprises a plurality of substantially identical circuit breaker units, of a kind known per se, (except in respect of minor variations, the nature of which will become apparent from what follows, to facilitate coupling of such units together in a manner to be described), coupled together by means, including coupling elements interposed between the units and cooperating with the mechanisms thereof, as will appear from what follows.

Each circuit breaker unit incorporates a latch mechanism substantially as described in detail in German Offenlegungsschrift 2830648 and described briefly below.

Referring to Figure 1, the circuit-breaker unit latch shown comprises a two-armed release lever 1 mounted on a pivot 2. One arm 3 of lever 1 is substantially horizontal while the other arm 4 extends downwardly at an angle. Arm 3 is subject to the action of a magnetic overcurrent release (not shown) while arm 4 is subject to a bimetallic overcurrent element (not shown), lever 1 being pivoted clockwise in the direction of arrow 5 by said release devices. The underside of arm 3 bears a sharp-edged heel 6. A hairpin spring (not shown) imparts an anti-clockwise torque to the lever 1.

A lever 7 acting as a carrier for a pawl described hereinafter is mounted pivotally on pin 2. This lever will hereinafter be referred to as the pawl carrier and it has a stud 8 on each side at the bottom end. One side of a stirrup shaped pawl 9 is mounted pivotally by a slot on each of the studs 8. The said sides are connected at the top ends by a yoke 10, the top edge of which is adapted to engage behind the heel 6 of the lever 1. The bottom ends of the pawl sides are drilled, a second pivot 11 extending through the holes. The ends of the pivots 2 and 11 each pass through a slot (not shown) in the large side surfaces of the housing and cover, the slots being slightly inclined to the vertical and being bounded by a beaded edge. The end 12 of contact lever 13 is also pivotally mounted on the second pivot 11.

One side of a bowed member 14 is also mounted on pivot 2, said part being offishplate shape, the bowed member being pivotally connected to a rocker (not shown). The bowed member 14 and the rocker are unimportant in this context, and they will therefore not be explained in detail. In this connection reference may be had to German Offenlegungsschrift 2830 648 referred to above. The drawing also shows a part of the housing wall in the form of a rib at 15.

Referring to Figures 2 and 3, two circuit-breaker units are assembled with abutting side walls 17 and 18, which may be part of the cover or housing.

Figures 2 and 3 again show the pivots 2 while Figure 2 shows the studs 8 for the pawl holder 7 (Figure 1), one side of the pawl 9 being mounted pivotally on each such stud 8. The side walls 17, 18, have a recess 19 (Figures 2 and 3) and an aperture 20 (Figures 1 to 3). A coupling element 21 is disposed in the two merging recesses 19 and the two equally large and coinciding apertures. Element 21 comprises a carrier plate 22 extending parallel to the side walls 17 and 18, and two projections 23 and 24 extending perpen dicularlyto and on either side of the plate 22.

Projections 23 (for the sake of clarity these are not shown in Figure 3) are lug-shaped while the projections 24 (not shown in Figure 2) are pin-shaped. All the projections 23, 24 extend into the interior of the two abutting circuit-breaker units. As will be seen from Figures 1 and 2, the lug-shaped projections 23 are situated in front of the studs 8 of the pawl holder 7, as considered in the clockwise direction. It will be seen from Figures 1 and 3 that pin-shaped projections 24 are situated below a projecting edge 25 of arm 3 of each release lever 1. Carrier plate 22 is mounted to pivot freely on a projection 26 formed on the outside of one of the side walls.

In the event of an overcurrent, the magnetic release acts on arm 3 or else the bimetallic release element acts on arm 4 of the lever 1, which thus pivots in the clockwise direction (Figure 1), releasing the pawl 9 as a result. The pressure of a contact spring (not shown) acting on contact lever 13 causes the second pivot 11 to be pushed upwards in its slot so that lever 13 comes into contact with the end of the part 15 of the wall and pivots about the resulting abutment so that the contact is opened. At the same time, the studs 8 of the pawl holder 7 are pressed to the left by the pawl 9 so that the latter and the holder 7 assume the intermediate position shown in Figure 4, while the contact lever 13 is finally in the break position shown in Figure 4.The first pivot 2 and the bowed member 14 initially do not change their positions because the rocker is subject to a torque in opposition to a torsion spring (not shown) during the movement of the second pivot 11 in its slot, said torque continuing to be exerted via the pawl 9, pawl holder 7 and bowed member 14.

It will be apparent from the above that after the pawl 9 has been released the pawl holder 7 pivots about the pivot 2 into the intermediate position shown in Figure 4. in these conditions the projection 23 on the coupling element 21 bears permanently against the stud 8 of the pawl holder 7, so that the coupling element 21 also pivots about the projection 26. Consequently, projection 24 on the opposite side of the plate 22 bears against the underside of the edge 25 of the release lever 1 of the adjacent circuit breaker unit and lifts the same or pivots it about the pivot 2. As a result, pawl 9 of the adjacent circuit breaker unit is also released and its switch contact is opened.

If another circuit breaker unit is similarly connected to this adjacent circuit breaker unit, the tripping procedure is correspondingly transmitted thereto. Tripping also occurs similarly if there is another circuit-breaker unit on each side of a given unit, because the latching system provided is symmetrical, i.e. there is a stud 8 of the pawl holder 7 and a projecting edge 25 of the release lever 1 on each side. Since the release of the pawl 9 and the pivoting movement of the pawl holder 7 take place abruptly, and the pivoting movement of the coupling element 21 occurs with practically no friction, the continued release of the adjacent circuit breaker units takes place within the minimum amount of time, i.e. with practically no delay.On manual re-make by actuation of the rockers of the individual circuit-breaker units, the respective release levers 1 drive the coupling elements 21 by way of the projections 24 and bring them into the initial position shown in Figure 1.

The toggle lever system of the latch illustrated passes out of the intermediate position shown in Figure 4 into a stretched position in which the stud 8 of the pawl holder 7 is situated at the place 8' indicated, the rocker (not shown) being thrown. This is unimportant to the tripping of adjacent circuitbreaker units as described. Those circuit-breaker units in which the release lever 1 is not, or is no longer, subject to the action of a magnetic or thermal release system, can be actuated individually if the rockers of all the circuit-breaker units are not mechanically interconnected. This is possible because in the present latch system the pawl holder 7 does not perform a pivoting movement on manual re-make, but moves rectilinearly downwards so that the release lever 1 can unobstructedly bring the associated coupling element 21 into the initial position shown in Figure 1. This individual actuation facility is important, for example, if signal contacts are required to be actuated.

Claims (4)

1. A multi-pole line circuit breaker comprising a plurality of adjacent narrow circuit-breaker units, each having overcurrenttripping means and manual tripping operated by means of a rocker, each unit having a latch in the form of a toggle lever system in a dished housing between the rocker and a contact lever, said latch comprising a release lever and a pawl connectd to the contact lever and adapted to engage the release lever, a coupling element mounted to be freely pivotable being provided to transmit tripping between the latches of adjacent circuit-breaker units, said coupling elements comprising a carrier plate and driver projections engaging in the latches and extending through apertures in the adjacent side walls of the housings, one set of such projections being associated with the pawls and the others being associated with the release levers of the adjacent circuit-breaker units, and wherein the carrier plate for the coupling element is mounted in external recesses in the abutting side wall of the housings, and each of one set of driver projections projecting on either side of the carrier plate of the coupling element is associated with one of two lateral studs on a latch pawl holder in the form of a lever mounted for pivoting coaxially of the pivot of the release lever at one end, said pawl holder bearing the pawl by means of the studs at its other end, the arrangement being such that only when the pawl is disengaged from the release lever, as a result of overcurrent tripping, does the pawl holder pivot about its pivot and pivot the coupling element by way of one of the studs which the associated driver projection abuts, the coupling element in turn acting on the release lever of the adjacent circuit-breaker unit via its other driver projections projecting on either side of the carrier plate.

2. A line circuit-breaker according to claim 1, in which one of the abutting housing side walls is provided with a projection for mounting the carrier plate of the coupling element.

3. A line circuit-breaker substantially as hereinbefore described with reference to, and as shown in, the accompanying drawings.

4. Any novel feature or combination of features described herein.