GB2043348A

GB2043348A - A fault-current circuit breaker

Info

Publication number: GB2043348A
Application number: GB7908510A
Authority: GB
Original assignee: Felten and Guilleaume Austria AG
Current assignee: Felten and Guilleaume Austria AG
Priority date: 1978-03-02
Filing date: 1979-03-10
Publication date: 1980-10-01
Also published as: FR2451098A1; AT353884B; GB2043348B; BE874841A; CH643395A5; DE2912028A1; FR2451098B1; ATA148078A; NL7902243A

Abstract

A fault-current circuit breaker comprises a casing body (1) containing a totalizing current transformer (2) with the terminals and the switch contacts, a latch mechanism assembly (7) with fault-current tripping device (8) and testing block, and a housing cover (10). The axis of symmetry of the transformer (2) and the plane of symmetry of the latch mechanism assembly (7) are located in the plane of symmetry of the casing body (1). The latch mechanism assembly (7) is L-shaped and engages with one side 20 in the casing body (1) whereas the totalizing current transformer (2) is held in a positive manner in the recess formed by the other side and the casing body (1). <IMAGE>

Description

SPECIFICATION A fault-current circuit breaker In the construction of modern fault-current circuit breakers, on account of the high number of indi vidual parts used, it is particularly important that assembly can take place quickly and therP.fore cheaply. Nevertheless, the reliability and precision of tripping when a fault-current occurs should not be impaired, since the latter are protective applicances on which peoples lives may depend.

In the case of low voltage switching devices, in particularcontactors, in order to achieve rational manufacture, a technique has been used success fully, which consists as far as possible of the non screwed assembly of pre-manufactured sub assemblies which can generally be plugged into each other. On the other hand, in the case of protec tive circuit breakers, a non-screwed plug-in assem bly is not yet in common use. References to this effect are contained in German Auslegesschrift No. 1 123751, which describes a protective circuit breaker consisting of two sub-assemblies. One sub assembly is formed by the socket with the switch contacts and the second sub-assembly consists of the latch with the tripping members.Austrian Patent Specification No. 284243 also describes a protective circuit breaker which is composed of sub assemblies. Austrian Patent Specification No. 339 991 likewise describes a protective circuit breaker, in which a support member is located at right-angles on a socket, the latch being located on one side of the support member and the tripping members being located on the other side.

However, all the solutions mentioned hitherto do not achieve the most favourable possible arrange ment of the individual parts for a fault-current circuit breaker, because it was always attempted to achieve several objectives simultaneously, for example tripping the fault current and fault voltage. However, when keeping solely to tripping due to fault-current, which are ascertained by a totalizing current transformer, the components can be arranged and assembled so that with the smallest space requirement, the smallest consumption of material occurs for the totalizing current transformer, fault-current tripping device, testing block and latch and a reliable operation is nevertheless ensured.At the same time it is possible for the components to be assembled easily and therefore cheaply and adjustment of the fault-current tripping device is possible even after fitting of the latch in the casing body.

Progress in this direction is represented by the construction described in German Offen legungschrift No. 1 638334. The latter describes a fault-current circuit breaker, in which the axis of symmetry of the totalizing current transformer and the plane of symmetry of the latch are arranged in the plane of symmetry of the casing body. The testing device and tripping relay are attached to a U-shaped support, on both sides of the latch. However, the numerous connecting members, consisting of rivets and screws are a drawback in this solution.

As afore-mentioned, a substantial amount of assembly time can be saved by a plug-in assemble which is largely free from rivets and screws and the fault-current circuit breaker for a plug-in assembly described hereafter has these inventive advantages.

It consists of a casing body containing the totalizing current transformer, the terminals and the switch contacts, of a latch with fault-current tripping device and testing block and of a casing cover. The axis of symmetry of the totalizing current transformer and the plane of symmetry of the latch are arranged such that they are located in the plane of symmetry of the casing body. According to the invention, one side of the L-shaped latch engages in the casing body and retains the totalizing current transformer positively in the recess formed by the other side and the casing body.

In the case of the side of the L-shaped latch engaging in the casing body, spring claws are provided according to the invention in the two latch plates, by which claws the latch is retained by friction in a rectangular hole in the casing body. After screwing the casing cover to the casing body, the L-shaped latch is secured in its position according to the invention, which latch in turn retains the totalizing current transformer in a positive manner. The side of the L-shaped latch, which secures the totalizing current transformer in position, supports the fault-current tripping device on one side and the testing block on the other side. Thus, according to the invention, the fault-current tripping device and the testing block are fixed in their position in the latch plates by peg and hole connections and are pressed against the latch plates by a spring clip.

Two identical symmetrical slides which actuate a re-setting device for the fault-current tripping device and a circuit-interrupting contact in the testing block are provided according to the invention in the side of the L-shaped latch which engages in the casing body. A common shaft is provided according to the invention at the outer corner of the L-shaped latch, which shaft is used for a pawl rest and for theresetting device of the fault-current tripping device.

The toggle joint chain which is located in the side of the L-shaped latch, which engages in the casing body, comprises a toggle joint, which acts according to the invention on a rotary lever, which in turn drives a tripping pawl constructed as a one-armed lever by way of the side of a slot provided in this tripping pawl, due to which, according to the invention, as a result of these lever transmissions, the pressing force on the pawl rest is less than if the toggle joint were to actuate the tripping pawl directly with the same spacing between the toggle joint and pawl rest.

The invention is described in detail with reference to the drawings which show one embodiment.

Figure lisa side view before the plug-in assembly with sectional views of the casing cover 10 and the casing body 1 on line A-B of figure 2b, the L-shaped The drawings originally filed were informal and the print here reproduced is taken from a later filed formal copy.

latch 7 and the totalizing current transformer 2. Fig ure 2a shows the assembled fault-current circuit breaker in side view, once more with the casing cover 10 and casing body 1 in sectional view on line A-B. It can be seen from figure 2a that the L-shaped latch 7 and the totalizing current transformer 2 is held positively by screwing the casing cover to the casing body. In the plan view of figure 2b, the casing cover has been taken off and the fault-current tripping device 8 and testing block 9 have been removed in order to make the totalizing current transformer 2 visible. Figure 3 shows the latch 7, the fault-current tripping device 8, the testing block 9 and the spring clip 11, before assembly. Figure4 shows the same components, after they have been connected to form one unit by the peg and hole connections and the spring clip 11.Figure 5a is a plan view, figure 5b shows the left-hand side view and figure Sc the right-hand side view of this component in detail and figure 6 explains the mechanical force ratios of the latch. Figure 6a shows a latch in which the toggle joint 17 actuates the tripping pawl 19 directly. Figure 6b shows the arrangement according to the invention, in which the toggle joint 17 acts on a rotary lever 18, which in turn drives a tripping pawl 19 equipped with a slot and acting as a one-armed lever.

As can be seen from figure 1 and figures 2a and 2b, the axis of symmetry of the totalizing current transformer 2 and the plane of symmetry of the latch 7 are located in the plane of symmetry of the casing body 1. The L-shaped latch 7 thus engages with one side in the casing body and the totalizing current transformer 2 is held in a positive manner in the recess formed by the other side of the latch and the casing body. As can be seen from figures 5b and 5c, the two latch plates of the L-shaped latch 7 have spring claws 20, so that the side of the latch which engages in the casing body 1 is held by friction in a rectangular hole in this casing body (figures 2a and 2b). After screwing the casing cover 10 to the casing body 1, the L-shaped latch 7 is in turn secured in position by the casing cover (figure 2a).Figure 3 shows the L-shaped latch 7, the fault-current tripping device 8, the testing block 9 and a spring clip 11. The fault-current tripping device and testing block comprise projecting pegs which fit in corresponding holes in the latch plates of the latch and secure the three components in their respective positions. They are held together by the spring clip 11. Figure 4 shows the assembled unit consisting of the L-shaped latch 7, the fault current tripping device 8, the testing block 9 and the spring clip 11. Figures 5a, 5b and Sc show details of this assembled unit.Provided in the side of the L-shaped latch, which engages in the casing body 1 are two identical symmetrical slides 12, which actuate a re-setting device 13 for the faultcurrent tripping device 8 and a circuit-interrupting contact 14 in the testing block 9. Located on the outer corner of the L-shaped latch 7 is a common shaft 15, which is used both for a pawl rest 16 and for the re-setting device 13 ofthefault current tripping device 8.

ifl a lFault-currenr: circuit breaker, it is of great sig nificance to provide reserves for the low force of the fault-current tripping device in the latch, that is to say the latch can be tripped with a force which is as low as possible. Therefore, the pawl rest, which must be moved by the fault current tripping device, must be able to move easily and this once more means that the contact pressure of the tripping pawl of the latch must be as low as possible. This contact pressure is determined by the contact force and the lever transmissions. The dimensions of the latch are also predetermined. If the toggle joint acts directly on the tripping pawl, then according to figure 6a, the withdrawal force PA of the pawl rest is determined by Pk.. . . Contact force m . . . . .Lever arm of the tripping pawl at the toggle joint n1.. .. Lever arm of the tripping pawl at the pawl rest ... .. Coefficient of friction.

As shown in figure 6b, according to the invention a rotary lever 18 is located between the toggle joint 17 and the tripping pawl 19. This rotary lever 18 drives the tripping pawl 19 provided with a slot, which pawl acts as a one-armed lever on the pawl rest 16. The withdrawal force PA of the pawl rest can now be calculated by Pk . Contact force m . . . . . Lever arm of the rotary lever at the toggle joint .... . . Lever arm of the rotary lever with respect to the tripping pawl o .. . . . Lever arm of the tripping pawl with respect to the pawl rest p . . .. . Lever arm of the tripping pawl with respect to the engagement point of the rotary lever.

It will benoted that with the same distance between the toggle joint 17 and pawl rest 16 in figures 6a and 6b, which are determined by the dimensions of the L-shaped latch 7, the withdrawal force of the pawl rest 16 in the arrangement according to figure 6b is less than that of figure 6a if Thus, due to a suitable choice of the lever transmission p/o, in the case of the tripping pawl 19 acting as a one-armed lever, one could thus reduce the withdrawal force of the pawl rest as desired. Constructional limits naturally exist in this respect, but halving of the force is possible without great difficulty.

Claims

1. Fault-current circuit breaker consisting of a casing body containing the totalizing current transformer, the terminals and the switch contacts, a latch Juith fault-current tripping device and testing block and a housing cover, the axis of symmetry of the totaliing current transformer and t311e :Iane of sym- metry of the latch are located in the plane of symmetry of the casing body, characterised in that the L-shaped latch engages with one side in the casing body, whereas the totalizing current transformer is held in a positive manner in the recess formed by the other side and the casing body.

2. Circuit breaker according to Claim 1, characterised in that the side of the L-shaped latch engaging in the casing body is held by friction in a rectangular hole in the casing body by spring claws which are provided in the two latch plates.

3. Circuit breaker according to Claims 1 and 2, characterised in that the L-shaped latch securing the totalising current transformer in position in a positive manner is in turn secured in position by the casing cover after the latter is screwed to the casing body.

4. Circuit breaker according to one of Claims 1 to 3, whereby on the side of the L-shaped latch securing the totalizing current transformer in position, the fault-current tripping device is arranged on one side and the testing block is arranged on the other side, characterised in that the fault-current tripping device and testing block are secured in position by peg and hole connections in the latch plates and are pressed against the latch plates by a spring clip.

5. Circuit breaker according to one of Claims 1 to 4, characterised in that provided in the side of the L-shaped latch which engages in the casing body are two identical symmetrical slides which actuate a re-setting device of the fault-current tripping device and a circuit-interrupting contact in the testing block.

6. Circuit breaker according to one of Claims 1 to 4, characterised in that on the outer corner of the L-shaped latch, a common shaft is used for a pawl rest and for the re-setting device of the fault-current tripping device.

7. A circuit breaker according to one of claims 1 to 4, characterised in that provided in the side of the L-shaped latch which engages in the casing body is a toggle joint, which acts on a rotary lever, which in turn drives a tripping pawl constructed as a onearmed lever by way of the side of a slot provided in this tripping pawl, due to which, as a result of these lever transmissions, the pressing force on the pawl rest is less than if the toggle joint were to actuate the tripping pawl directly, with the same space between the toggle joint and pawl rest.