AU639986B2

AU639986B2 - A circuit breaker

Info

Publication number: AU639986B2
Application number: AU72256/91A
Authority: AU
Inventors: Hendrik Adolf Bosch; Raymond Burke; Soedjimat Francesco Darmohoetomo; James Early; Oliver Glennon; Martin Francis Healy; James Shortt
Original assignee: Square D Co
Current assignee: Schneider Electric USA Inc
Priority date: 1990-02-23
Filing date: 1991-01-21
Publication date: 1993-08-12
Anticipated expiration: 2011-01-21
Also published as: DE69113364T2; AU7225691A; EP0470215A1; DE69113364D1; JP2735384B2; IE71036B1; EP0470215A4; IE900656A1; CA2053238A1; EP0470215B1; WO1991013454A1; JPH04507168A

Description

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0711v/MS 1 A CIRCUIT BREAKER Technical Field The invention relates to circuit breakers and in particular to circuit breakers of the type having both over-current and earth leakage protection, commonly referred to as residual current circuit breakers (RCCB's).

Prior Art Over-current protective devices have limitations such as delay in operation in situations where there is a relative high earth loop impedance. Further, over-current protective devices do not detect earth fault currents below their operating current, which currents in certain circumstances "i may constitute a fire hazard. Accordingly, there is an increasing demand for protective devices providing both over-current and earth leakage protection.

C Summary of the Invention In one form the present invention is a circuit breaker for use in a system having live, neutral and ground leads, comprising: a housing; a breaker assembly in the housing for making and I I- 0711v/MS 0711v/MS -2breaking an electrical connection between a movable contact and a stationary contact; an operating handle for the breaker assembly; an over-current sensing means for tripping of said breaker assembly; the over-current sensing means including a coil and a armature core in the coil; the armature core having an axial bore extending therethrough; and an additional tripping mechanism responsive to a residual current fault; the additional tripping mechanism comprising: a plunger means mounted within the axial bore of the armature core for movement into contact with said breaker assembly from a non-tripping position to a tripping position where said movable contact is moved away from said stationary contact in order to trip said breaker; an actuating device for controlling the movement of the t 't plunger means from the non-tripping position to the tripping i position when a residual current fault is detected; the plunger means being independently movable through the axial bore in the armature core when moving between the non-tripping and tripping positions, and 4 reset means being provided for resetting of the plunger means to the non-tripping position.

In a particularly preferred aspect of the circuit breaker is a residual current circuit breaker and includes a residual current detection circuit for detection of a residual current a(#u I

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0711v/MS 3 in the system, and the actuating device comprises a residual current actuating device for controlling the movement of the plunger means between a non-tripping position and a tripping position when a residual current fault is detected by the detection circuit.

In one embodiment of the invention the actuating device comprises a drive rod which is movable on detection of a residual current fault between a non-tripping position and a tripping position in which the drive rod engages the plunger means to drive the plunger means into the tripping position, biassing means for urging the drive rod into a tripping i ct t*r t L C P i n r CCil

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C r fr l~ 1-r' i I rr Il 1 WO 91/13454 PCT/US91/00380" -4position, and retaining means for retaining the drive rod in a non-tripping position.

Preferably the retaining means comprises a permanent magnet to hold the drive rod in the non-tripping position and electromagnet to neutralise the effect of the permanent magnet on the drive rod on detection of a residual current fault.

In one arrangement the biassing means comprises a spring means for driving the drive rod into a tripping position engaging the plunger.

Preferably the reset means comprises a reset lever interposed between the drive rod and the plunger and a reset actuator for moving the lever to return the drive rod into the non-tripping position against the action of the biassing means.

In a preferred arrangement the reset actuator comprises the circuit breaker operating handle which engages the reset lever when the handle is moved from the on or non-tripped position with the contacts closed to the off or tripped position with the contacts opened.

Preferably the reset lever is pivotally mounted to the housing intermediate the ends thereof and comprises a first lever arm for engagement by the operating handle and a second lever arm interposed between the drive rod and the plunger means.

WO 91/13454 PCI/US91/00380 5 Typically the reset lever is of substantially L shape in plan view.

In a preferred embodiment of the invention the plunger means comprises a single plunger rod extending through the bore in the armature core. Preferably the plunger rod is of nonferrous, preferably plastics material.

In one embodiment of the invention engagement means are provided intermediate the ends of the plunger rod for engagement by the armature core on movement of the armature core in the event of an overcurrent fault occurring from a non-tripping position in which the armature core is retained by a spring biassing means to a tripping position in which current flowing through the coil draws the armature core through the coil against the biassing of the spring means to engage the plunger rod and trip the breaker assembly in the event of an overcurrent fault occurring. Preferably the engagement means is provided at substantially the mid point along the longitudinal axis of the plunger rod so that the rod is substantially symmetrical.

In one arrangement the engagement means comprises a radially outwardly extending collar engagable in a complementary shaped recess in the armature core.

WO 91/13454 PCT/US91/00380' 6- Preferably the plunger rod is slidably mounted in a bushing provided in the coil at the end thereof remote from the armature core.

In another embodiment of the invention the actuating device comprises a solenoid.

In a further embodiment of the invention the actuating device is operated from a remote location.

In one embodiment of the invention position sensing means are provided for sensing the position of the plunger means.

Preferably the position sensing means comprises switch means operated Ly the plunger means on movement between the nontripped and tripped position.

The invention will be more clearly understood from the following description of some preferred embodiments thereof f given by way of example only with reference to the accompanying drawings in which: Fig. 1 is a plan view of a circuit breaker according to the invention, Fig. 2 is a plan, partially cross-sectional view of the cirrcit breaker of Fig. 1, .1WO 91/13454 nl.

I~ 91/00380 I W091/13454 PCT/US91/00380 WO 91 7 bushing e rom the Fig. 3 is a cross-sectional view of a tripping portion of a the circuit breaker in an on position, and c a device Figs. 4 to 7 are plan views of the tripping position in 5 a different positions. c device 5 Referring to the drawings, and initially to Figs. 1 to 3 there 1 is illustrated a circuit breaker in this case a residual b< current circuit breaker (RCCB) according to the invention Lns are indicated generally by the reference numeral 1. The RCCB 1 10 T] comprises a housing 2 having a base and a cover which form a rE partition wall 3 which separates an over-current protection p1 means device 4 from an additional tripping means which in this case tk e non- includes a residual current detection circuit 5. The RCCB 1 a includes line and neutral supply terminals 6 and 7, and 15 bl neutral line load terminals 8 and 9, and an earth terminal 10. cc m the 15 In this case, the line supply terminal 6 is formed by a metal ir hereof clip for both mechanical and electrical connection with a ac the supply conductor. The line and neutral load terminals 8 and pl S; 9 are of the screw-type and are in side-by-side relationship 20 po in a side wall of the housing 2. The neutral supply terminal de ng to 20 7 and the earth terminal 10 are of the conventional cable ro type. fa 23 f the The RCCB 1 includes a breaker assembly 15 which in this case 25 fo is of the unitary type and includes a movable contact 16 for th WO 9 W41 f.n.on I WO 91/11U«; DiT/I ICe/nnan r wr o OWO W091 SWO 91/13454 PCT/US91/00380 -8engagement with a fixed contact 17. The breaker assembly as also includes an operating handle 18 of conventional ro construction. The over-current protecting device 4 comprises ne a bi-metal element 19 abutting the breaker assembly 15 and an in I 5 arc stack 27 of conventional construction. The device 4 also 5 3 comprises a coil 20 having an armature 21 and having an Th armature core 22 which is biassed into a non-tripping position ere illustrated in Figs. 1 and 2 by a coil spring 26. An axial in bore 23 extends through the core 22.

Lual is :.ion 10 co B 1 10 The additional tripping means which in this case operates in0 co Sa response to a residual current fault occurring includes a th :ion plunger means comprising a single plunger rod 24 which extends as :ase through the partition wall 3, through the bore 23 and through ei :B 1 a plunger bushing 25 to impact against a trip lever 28 of the and 15 breaker assembly 15 for moving the contact 16 away from the contact 17 to trip the breaker. The additional tripping means tr tal Iincludes the residual current detection circuit 5 and an be ha actuating device 30 for controlling the movement of the h a ac and plunger rod 24 between a non-tripping position and a tripping and 31 hip 20 position when a residual current fault is detected by the Lnal detection circuit. The actuating device 30 comprises a drive ble rod 31 which is movable on detection of a residual current enc fault to engage and drive the plunger rod 24 through the bore wh( 23 to trip the breaker. The drive rod 31 is biassed into a 25 forward or tripping position by a coil spring 32 wound around po case for the rod 31. Retaining means for retaining the drive rod 31 in 25 po for r Wt 01 I1ACA

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WO 91/13454 PCrT/US91/00380 -9a non-tripping or retracted position comprises a magnetic assembly 35 comprising a permanent magnet to hold the drive rod 31 in a non-tripping position and an electromagnet to neutralise the effect of the permanent magnet on the drive rod 31 on detection of a residual current fault by the circuit The plunger rod 24 is in this case of non-ferrous, preferably plastics material. The rod 24 includes an engagement means in the form of a radially outwardly extending collar 50 which is engagable in a complementary shaped recess in the armature core 22. The collar 50 is provided substantially at the midpoint along the longitudinal axis of the plunger rod 24 so that the rod 24 is substantially symmetrical. Thus, on assembly, the rod 24 may be inserted into the bore 23 in either direction.

Reset means for re-setting of the plunger rod 24 to a nontripping position comprises a reset lever 40 interposed between the drive rod 31 and plunger rod 34 and a reset actuator for moving the lever rod 40 to return the drive rod 31 into the non-tripping position against the action of the spring 32. In this case the reset actuator comprises the 4rcuit breaker operating handle 18 which includes an engagement surface 45 which engages against the reset lever when the handle 18 is moved from the on or non-tripped position with the contacts 16, 17 closed to the off or tripped position with the contacts 16, 17 open.

WO 91/13454 PCT/US91/00380 10 The reset lever 40 is pivotally mounted to the housing 2 intermediate the ends thereof, is of generally shape in plan view and comprises a first arm 46 for engagement by the engagement surface 45 of the operating handle 18 and a second arm 47 interposed between the drive rod 31 and plunger rod 24.

A test mechanism for checking the operation of the residual current tripping device comprises a test button 60 engagable against a lever 61 which is pivotally mounted to the housing 2 by a pivot pin 62. A spring 63 biasses the lever 61 into the non-test position illustrated in Figs. 1 and 2. The spring 63 is electrically connected to the coil 20 at one end and the lever 61 is arranged to move the other end of the spring 63 between a non-test position as illustrated in Figs.

1 and 2 to a test position in contact with a push to test terminal 64.

'n use, and referring particularly to Figs. 3 to 7 in the normal non-tripped position illustrated in Fig. 3 the handle 18 is in the o. positiorn, the drive rod 31 is retracted, the reset lever 40 is at right angles to the drive rod 31, the armature core 22 is retracted, the plunger rod 24 is retracted and the contacts 16, 17 are closed. In the event of a residual current fault being detected by the circuit 5 the electromagnet of the magnetic assembly 35 is activated to neutralise the effect of the permanent magnet restraining the x

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3003M/MS WO 91/13454 PCT/US91/00380 11 drive rod 31, allowing the rod 31 to extend outwardly under the action of the spring 32, striking the lever arm 47 of the reset lever 40 forwardly about its pivot to strike the plunger rod 24 which moves independently through the bore 23 of the armature core 22 to strike the lever 28. This configuration is illustrated in Fig. 4. The striking of the lever 28 releases a spring which moves the contact 16 away from the contact 17 and the handle 18 is thrown towards the off position as illustrated in Fig. As the handle 18 travels into the off position the engagement surface 45 of the handle 1E strikes the arm 46 of the reset lever 40 as illustrated in Fig. 5, pivoting the lever anticlockwise and thus pushing the arm 47 of the reset lever against the plunger rod 31 driving it back into the magnetic assembly housing against the biassing of the spring 32. The plunger rod 24 is then free to move back through the bore into the reset position illustrated in Fig. 6. When the handle 18 is thrown back into the on position the additional tripping device is in the non-tripping position illustrated in Fig. 3.

jI Referring to Fig. 7 in the event of an overcurrent fau.t developing the armature 'core 22 is drawn into the coil against the biassing of the spring 26, the recess 51 of the core 22 engaging with the collar 50 on the plunger rod 24 to I jj Sr&jICual current fault; i the additional tripping mechanism comprising: ja plunger means mounted within the axial bore of the ./2 0711v/MS 12drive the plunger rod 24 forward through the coil 20 to trip the breaker by striking the lever 28.

One advantage of the breaker of the invention is that because the plunger means is independently movable through the armature core it performs the function of tripping the breaker independently of the armature core. There is no magnetic interference between the trip mechanism via movement of the armature core in the event of an over-current fault and movement of the plunger means in the event of a residual current fault. Further, the plunger means may be used in association with a position sensing means such as an auxiliary switch to give a remote 8O indication of the closed or open status of the breaker. The position sensing means may detect the position of the contacts directly or indirectly by sensing the position of tne plunger.

e* Auxiliary and command devices either locally or remotely operated may be used as an alternative to the residual current detection circuit to provide a tripping signal in o:o the event of a fault or test condition occurring.

It will be appreciated that the invention, provides an RCCB which is relatively simple and is reliable in operation.

The use of a separate drive rod 31 and plunger rod 24 allows the choice of suitable materials, in this case a plastics plunger 'L T .v l j v to a E the /2 ~yi

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Claims

14- The claims defining the invention are as follows: 1. A circuit breaker for use in a system having live, neutral and ground leads, comprising: a housing; a breaker assembly in the housing for making and breaking an electrical connection between a movable contact and a stationary contact; an operating handle for the breaker assembly; an over-current sensing means for tripping of said breaker assembly; the over-current sensing means including a coil and a armature core in the coil; the armature core having an axial bore .;xtending therethrough; and an additional tripping mechanism responsive to a residual current fault; the additional tripping mechanism comprising: a plunger means mounted within the axial bore of the goo* armature core for movement into contact with said breaker assembly from a non-tripping position to a tripping position Goo where said movable contact is moved away from said stationary contact in order to trip said breaker; 0. 0 an actuating device for controlling the movement of the plunger means from the non-trippinQ position to the tripping position when a residual current fault is detected; the plunger means being independently movable through the axial bore in the armature core when moving between the non-tripping and tripping positions, and V"r 0 i ^feoj 0711v/MS reset means being provided for resetting of the plunger means to the non-tripping position. 2. A circuit breaker as claimed in claim 1 wherein the breaker includes a residual current detection circuit for detection of a residual current in the system, and the actuating device comprises a residual current actuating device for controlling the movement of the plunger means between a non-tripping position and a tripping position when a residual current fault is detected by the detection circuit. S 3, A circuit breaker as claimed in claim 2 wherein the actuating device comprises a drive rod which is movable on detection of a residual curre.t fault between a non-tripping position and a tripping position in which the drive rod engages the plunger means to drive the plunger means into 0 the tripping position, biassing means for urging the drive rod into a tripping position, and retaining means for retaining the drive rod in a non-tripping position. 0 i Si 1 L d a particularly preferred aspect of the circuit breaker is a residual current circuit breaker and includes a residual current detection circuit for detection of a residual current WO 91/13454 PCT/US91/00380 16 4. A circuit breaker as claimed in claim 3 wherein the retaining means comprises a permanent magnet to hold the drive rod in the non-tripping position and electromagnet to neutralise the effect of the permanent magnet on the drive rod on detection of a residual current fault. A circuit breaker as claimed in claim 3 wherein the biassing means comprises a spring means for driving the drive rod into a tripping position engaging the plunger. 6. A circuit breaker as claimed in claim 3 wherein the reset means comprises a reset lever interposed between the drive rod and the plunger and a reset actuator for moving the lever to return the drive rod into the non-tripping position against the action of the biassing means. 7. A circuit breaker as claimed in claim 6 wherein the reset actuator comprises the circuit breaker operating handle which engages the reset lever when the handle is imoved from the on or non-tripped position with the contacts closed to the off or tripped position with the contacts opened. 8. A circuit breaker as claimed in claim 7 wherein the reset lever is pivotally mounted to the housing intermediate the ends thereof and comprises a first lever arm for engagement by 11. A circuit breaker as claimed in claim 10 wherein the A circuit breaker as claimed in claim 10 wherein occurring from a non-tripping position in which the armature 17 13. A circuit breaker as claimed in claim 12 wherein the engagement means is provided at substantially the mid point u VU &.Jlj intermediate the ends thereof and comprises a first lever arm for engagement by the operating handle and a second lever arm interposed between the drive rod and the plunger means. WO 91/13454 PCI/US91/00380, 18 along the longitudinal axis of the plunger rod so that the rod is substantially symmetrical. 14. A circuit breaker as claimed in claim 12 wherein the engagement means comprises a radially outwardly extending collar engagable in a complementary shaped recess in the armature core. A circuit breaker as claimed in claim 13 wherein the plunger rod is slidably mounted in a bushing provided in the coil at the end thereof remote from the armature core.

16. A circuit breaker as claimed in claim 1 wherein the actuating device comprises a solenoid.

17. A circuit breaker as claimed in claim 1 wherein the actuating device is operated from a remote location.

18. A circuit breaker as claimed in claim 1 wherein position sensing means are provided for sensing the position of the plunger means. 0711v/MS 19

19. A circuit breaker as claimed in claim 18 wherein the position sensing means comprises switch means operated by the plunger means on movement between the non-tripped and tripped position. A circuit breaker as substantially herein described and with reference to the accompanying drawings. 0@ *0 0 S. 0 0S0S O S S 050 S S* S S S 05 S 55 5 SO 0 S DATED this 17th day of May, 1593. SQAURE D. COMPANY By Their Patent Attorneys DAVIES COLLISON CAVE S 0