AU745538B2

AU745538B2 - Electrical breaking device comprising a differential trip device and a circuit breaker comprising such a device

Info

Publication number: AU745538B2
Application number: AU33157/99A
Authority: AU
Inventors: Michel Bonniau; Michel Lazareth; Bernard Lebeau
Original assignee: Schneider Electric SE
Current assignee: Schneider Electric SE
Priority date: 1998-06-04
Filing date: 1999-06-03
Publication date: 2002-03-21
Anticipated expiration: 2019-06-03
Also published as: EP0962952A1; EP0962952B1; HK1022043A1; ATE258715T1; FR2779568A1; CN1147897C; EA001567B1; AU3315799A; DE69914403D1; FR2779568B1; EA199900440A3; BR9902700A; ZA993751B; EA199900440A2; CN1238546A

Abstract

The differential release mechanism (9) may be actuated by a relay (16) and displacing a rod (19) between rest and activation positions. The starting point of the rod is arranged outside of the electromagnetic relay (7) and acts directly on the starting point tripping device (20) at the time of the occurrence of a differential defect. This same rod assures the resetting of the relay (16) after opening of the contacts.

Description

rIUU II ai w i Regulation 3.2(2)

AUSTRALIA

Patents Act 1990

ORIGINAL

COMPLETE SPECIFICATION STANDARD PATENT Application Number: Lodged: 1 Invention Title: ELECTRICAL BREAKING DEVICE COMPRISING A DIFFERENTIAL TRIP DEVICE AND A CIRCUIT BREAKER COMPRISING SUCH A DEVICE The following statement Is a full description of this invention, Including the best method of performing It known to us 1 ELECTRICAL BREAKING DEVICE COMPRISING A DIFFERENTIAL TRIP DEVICE AND A CIRCUIT BREAKER COMPRISING SUCH A DEVICE The field of the present invention relates generally to electrical breaking devices and more particularly, to devices with a reduced overall physical dimension as compared with prior art devices.

BACKGROUND ART A differential circuit breaker is known as described in the document EP- 0,665,569 filed by the applicant, comprising a differential trip unit laterally adjoined and coupled to a circuit breaker unit. In this document, the mechanism of the differential trip unit is joined to the mechanism of the circuit breaker unit by a mechanical tripping link acting on the trip bar of the circuit breaker unit for transmission of a differential tripping order.

However, due to the fact that the two units are laterally adjoined, the differential circuit breaker unit presents a large width and therefore a large overall dimension. The need therefore arose to reduce this dimension. One of the solutions envisaged consisted in locating the differential trip device and the circuit breaker in a single module and in the same plane. Such a device is described in US Patent 4,608,546. In this document, a single rod is used to perform tripping commanded either by the magnetic trip unit or by the differential trip unit. This striking rod is mounted freely sliding in the fixed core of the magnetic trip unit and can be driven in translation either by the plunger of the magnetic trip unit or by a differential trip rod commanded by the differential trip unit.

This device presents a certain number of drawbacks. One of these drawbacks lies in the fact that this striking rod has to be guided very freely inside 25 the fixed core and the plunger, as the differential energy produced by the differential trip unit is very small. This results in the pollution liable to be caused during breaking at the level of the radial clearances situated between the striking rod and the fixed core, or between the plunger and the differential trip rod, being able to generate blockages hindering correct operation of the differential.

Furthermore, the fact that this rod is freely sliding reduces the efficiency and production of the magnetic trip device since the plunger loses some of its striking energy.

The twofold function performed by the striking rod results in a stacking of clearances, i.e. a clearance at the level of the trip relay with the trip rod, a clearance between the trip rod and the striking rod and a clearance between the striking rod and the trip bar of the circuit breaker, plus a stacking of the longitudinal dimensions.

Moreover, the presence of two parts between the push-rod of the relay and the trip bar increases the inertias and response times.

Another drawback lies in the fact that the differential trip rod has to be nonmagnetic, as it must not be subject to the influence of the magnetic trip device.

Finally, in this device, resetting of the differential system is performed by the handle when the latter returns to its set position. This results in this resetting not taking place if the handle is prevented from returning, for example in the case of padlocking.

The present invention proposes a breaking device comprising a differential I 15 trip device, of simple design, in an attempt to ameliorate the problems encountered in the prior art devices.

o It is an advantage of the present invention to provide a breaking device of the kind referred to above, this device being characterized in that the trip rod is located outside the electromagnetic trip device and acts directly on the abovementioned trip part when a differential fault occurs.

Due to these features, the risks of friction liable to prevent sliding of the differential trip rod are eliminated. The efficiency of the magnetic trip device is not reduced, since it is no longer necessary for the striking rod to be freely sliding.

The clearances and risks of dispersion of the longitudinal dimensions are 25 reduced. The inertia of the parts and therefore the response times are also considerably reduced.

Any discussion of documents, devices, acts or knowledge in this specification is included to explain the context of the invention. It should not be taken as an admission that any of the material formed part of the prior art base or the common general knowledge in the relevant art in Australia on or before the priority date of the claims herein.

SUMMARY OF THE INVENTION In one aspect, the present invention provides an electrical breaking device including, located in a single narrow case, one appreciably in the extension of the other in a plane appreciably parallel to the large side panels of the case, an electromagnetic trip device designed to act on a trip part to command a trip device so as to bring about separation of stationary and movable contacts when a sudden current increase occurs and a differential trip device designed to act on the above-mentioned trip part to command the trip device so as to bring about separation of the contacts when an insulation fault occurs in an installation, said differential trip device including an actuating means designed to move an actuating rod between a rest position and a position actuating the trip part, wherein the actuating rod is located outside the electromagnetic trip device and acts directly on the above-mentioned trip part when a differential fault occurs.

In another aspect, the present invention provides a circuit breaker 15 incorporating an electrical breaking device including, located in a single narrow case, one appreciably in the extension of the other in a plane appreciably parallel Sto the large side panels of the case, an electromagnetic trip device designed to act on a trip part to command a trip device so as to bring about separation of stationary and movable contacts when a sudden current increase occurs and a differential trip device designed to act on the above-mentioned trip part to command the trip device so as to bring about separation of the contacts when an insulation fault occurs in an installation, said differential trip device including an S: actuating means designed to move an actuating rod between a rest position and a position actuating the trip part, wherein the actuating rod is located outside the 25 electromagnetic trip device and acts directly on the above-mentioned trip part when a differential fault occurs.

"Comprises/comprising" when used in this specification is taken to specify the presence of stated features, integers, steps or components but does not preclude the presence or addition of one or more other features, integers, steps, components or groups thereof.

BRIEF DESCRIPTION OF THE DRAWINGS But other advantages and features of the invention will become more clearly apparent from the following description of a particular embodiment of the invention, given as a non-restrictive example only and represented in the accompanying drawings in which: Figure 1 illustrates, in a longitudinal cross sectional view, a differential circuit breaker according to the invention, in a loaded position with contacts closed, Figure 2 is a similar view to the previous one, illustrating the differential circuit breaker in a position in which the contacts are closed and the differential relay tripped, just before opening of the contacts and, Figure 3 is a similar view to the previous one, illustrating the same circuit breaker in a reset position of the relay simultaneously with opening of the contacts.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT In the figures, a modular differential circuit breaker unit B can be seen designed to be connected to the electrical conductors of an AC power system by means of a connection terminal 1, in order to protect the power system when an overload, short-circuit or differential fault (or insulation fault) occurs.

S• This apparatus is housed in a narrow case 2 constituted in two parts one of *.o which has been removed so that the mechanism of the apparatus can be seen.

This case presents a top panel a, a bottom panel b, a front panel c, a rear panel d and two large side panels only one e of which is visible. This case mainly houses a pair of separable contacts 3, 4, respectively stationary 3 and movable 4, an a operating mechanism 5 commanding opening and closing of the circuit breaker S" actuated by a handle 6, an electromagnetic trip device 7, a thermal trip device 8, S. a differential trip device 9 and a circuit breaker trip device D.

The electromagnetic trip device 7 is designed to cause opening of the contacts when a short-circuit occurs. It comprises, in a manner known in itself, a coil 10 mounted on a sheath 11 inside which a fixed core (not represented) is fixed, and a plunger (not visible) secured to a striking rod 12 slides. This plunger is designed to move between a rest position and an active position in which the striking rod 12 acts on a trip part or trip bar 20, so as to cause separation of the contacts 3, 4, due to the effect of the magnetic field created the flow of a shortcircuit current through the coil.

The thermal trip device 8 is presented in the form of a bimetal strip 13 and is designed to activate the circuit breaker trip device D, so as to bring about separation of the contacts, when a current overload occurs.

The differential trip device 9 comprises a means for detecting a differential current in the form of a summing transformer 14, a test circuit with a test button (fig.l), an actuating means in the form of a relay 16, called magnetic latching relay, and an electronic processing circuit with an auxiliary power supply source 17 mounted on a printed circuit board.

In a manner known in itself, the summing transformer comprises a magnetic circuit in the form of a toroid through which there pass neutral and phase power conductors electrically connected to the bottom terminals of the circuit breaker unit and forming the primary winding of the transformer. A secondary winding is coiled onto the toroid and is electrically connected by wires to the input of the electronic circuit 17. The output of the electronic circuit is 15 connected by an electrical connection to the coil of the trip relay 16.

The trip relay 16 being known in itself, it will not be described in detail here.

This relay comprises a coil which, following an order given by the electronic go*o• S• circuit, is able to move a core 16b, which core 16b acts on a differential trip rod 19 when a differential fault occurs, so as to move the rod between a rest position and a position in which the rod 19 strikes the trip bar 20. A spring 18 is fitted between a bearing face 16a of the relay 16 and a bearing face of the core 16b.

As can be seen in the figures, the trip rod 19 extends between the above- S mentioned handle 6 and the coil 10 of the electromagnetic trip device 7, forming an angle of about 100 with the axis of this coil 10. This rod comprises a straight 25 part 19a terminated by a curved part 19b curved appreciably at 90' in the direction of the trip bar 20. The end of the rod 19c presents a slightly rounded shape corresponding to the shape of the part of the bar 20 designed to operate in conjunction with said rod 19.

The circuit breaker trip device D comprises in a manner known in itself a latching system 22, 20 arranged in such a way as to keep the movable contact 4 in the closed position by means of a plate 23 mounted rotating in the case and securedly affixed to the movable contact 4.

6 It can also be seen in the figures that the trip rod 19 comprises a nose 21 presenting, in the plane of the figure, an appreciably triangular cross section, and designed to operate in conjunction with (press on) the plate 23, so that the rotational movement of the plate 23 after each tripping results in resetting of the differential trip rod 19, i.e. movement thereof in the direction of the relay 16 against the force of the spring 18 until magnetic latching is re-established, as explained in greater detail in the following.

It can be noted that the rod 19 is guided in translation by positioning and guiding supports 24 securedly affixed to the side walls of the case.

This circuit breaker comprises in addition a test circuit with a test button, said button 15 being situated under the handle 6 and acting on a spring element situated laterally to the rod, said spring element connecting a test resistor I17a incorporated in the electronic circuit of the differential function to the potential of the shell of the coil Operation of the differential circuit breaker according to the invention will be described hereafter, with reference to figures 1 to 3, only when a differential fault is detected, its operation in case of an overload or short-circuit not being modified with respect to what is known from the prior art.

In figure 1, the circuit breaker is in a loaded position, with closed contacts, corresponding to normal operation of the electrical power sy stem. In this state, the rod 19 is kept in a rest position pressing on the core 16b of the relay, which core is held by the magnetic latching.

When an insulation fault occurs on the power system protected by the :9*9.*differential circuit breaker, the summing transformer 14 sends a tripping order to the electronic circuit 17, which after amplifying commands excitation of the coil of the relay 16. This causes magnetic unlatching of the core 16b of the relay 16, which drives the trip rod 19 (fig. 2) in translation in the direction of the trip bar due to the force of the spring 18 (the core comes unstuck, the spring being stronger, and it acts on the rod).

When this movement takes place, the rod, via its curved end 19b strikes the trip bar 20, which results in unlatching of the latching system 20, 22 keeping the movable contact 4 in the closed position by means of the plate 23. The plate 23 is driven counterclockwise in rotation until the contacts open due to the effect .<2tVSi~~- of a return spring. During this movement, the plate 23 strikes the nose 21 of the trip rod 19 and returns said rod 19 to a retracted position moving said rod 19 in the direction of the body of the relay 16 until magnetic latching of the core of the relay is re-established. This corresponds to the state of the circuit breaker represented in figure 3. The handle 6 can then be actuated manually in the clockwise direction until the contacts close, which corresponds to the state of the circuit breaker represented in figure 1.

Thus, due to the presence of this nose 21, resetting of the differential relay 16 is always performed immediately after differential tripping.

It can be noted that the invention applies both to breaking devices such as system-powered differential circuit breakers and to devices with an auxiliary power source.

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Claims

1. An electrical breaking device including, located in a single narrow case, one appreciably in the extension of the other in a plane appreciably parallel to the large side panels of the case, an electromagnetic trip device designed to act on a trip part to command a trip device so as to bring about separation of stationary and movable contacts when a sudden current increase occurs and a differential trip device designed to act on the above-mentioned trip part to command the trip device so as to bring about separation of the contacts when an insulation fault occurs in an installation, said differential trip device including an actuating means designed to move an actuating rod between a rest position and a position actuating the trip part, wherein the actuating rod is located outside the electromagnetic trip device and acts directly on the above-mentioned trip part when a differential fault occurs. !iii 2. The device according to claim 1, wherein the actuating rod performs resetting of the actuating means after opening of the contacts.

3. The device according to claim 2, wherein the actuating rod includes a nose designed to operate in conjunction with the trip device in such a way that actuation of the trip device results in resetting of the differential actuating means S. after opening of the contacts. S4. The device according to claim 3, wherein the trip device includes a latching system keeping the movable contact in the closed position by means of a rotary plate secured in rotation to the movable contact, and unlatching of the latching system due to the effect of actuation of the trip part resulting in rotation of the plate in one direction and separation of the contacts, the nose operates in conjunction with the plate so that rotation of the plate during tripping leads to resetting of the differential actuating means. The device according to any one of the claims 1 to 4, wherein the actuating means is designed to drive the actuating rod in translation parallel to its longitudinal axis between a rest position and a position actuating the trip part. 7 -1 i

6. The device according to any one of the foregoing claims, wherein the device includes a manual control handle of the contacts, the actuating rod extends between the handle and the magnetic trip device.

7. The device according to any one of the foregoing claims, wherein the magnetic trip device including a striking rod operating in conjunction with a coil, the actuating rod includes a straight part forming an angle of about 100 with the axis of the striking rod and a curved end part curved appreciably at right angles, in the direction of the end of the striking rod, said curved part operating in conjunction with the trip part.

8. The device according to any one of the foregoing claims, wherein the actuating means is a magnetic latching relay.

9. The device according to any one of the foregoing claims, wherein the S: device includes a test circuit with a test button, said test button being situated under the handle and acting on a spring element situated laterally to the rod, said spring element connecting a test resistor incorporated in the electronic circuit of the differential function to the potential of the shell of the coil.

10. A circuit breaker including a breaking device according to any one of the foregoing claims. S 11. The circuit breaker according to claim 10, wherein the trip part is a trip bar.

12. An electrical breaking device according to claim 1 substantially as herein before described with reference to the accompanying figures.

13. A circuit breaker according to claim 10 substantially as herein before described with reference to the accompanying figures. DATED this 10th day of December 2001 SCHNEIDER ELECTRIC SA WATERMARK PATENT TRADE MARK ATTORNEYS Unit 1 The Village Riverside Corporate Park

39-117 Delhi Road North Ryde New South Wales 2113 Australia PNF/NWM/MBL to S *9 r o •ooo•* .i I-I-7. I