AU2019204959B2

AU2019204959B2 - Residual current circuit breaker and method of testing same

Info

Publication number: AU2019204959B2
Application number: AU2019204959A
Authority: AU
Inventors: Dylan Mark-Anthony Bedetti; Gino Mark-Anthony Bedetti
Original assignee: Individual
Current assignee: Individual
Priority date: 2018-07-11
Filing date: 2019-07-10
Publication date: 2020-10-08
Anticipated expiration: 2039-07-10
Also published as: AU2019204959A1

Abstract

A residual current circuit breaker comprising a socket, the socket comprising at least first and second apertures configured to receive, removably, respective neutral and live pins of a plug connectable to an external residual current circuit breaker testing device. The residual current circuit breaker also comprises first and second conductors configured to connect, electrically, the neutral and live pins of the plug to respective neutral and live conductors of the residual current circuit breaker when the plug is in the socket. 1/10 10 32 34 14- - 12 Figure 1(a) 10 0 34i 36 12 Figure 1 (b)

Description

1/10 10

32

34

14- - 12

Figure 1(a)

10

0 34i

36

12

Figure 1 (b)

RESIDUAL CURRENT CIRCUIT BREAKER AND METHOD OF TESTING SAME

Field

[0001] The present invention relates to circuit breakers and, more particularly, to residual current circuit breakers and testing methods thereof.

Background

[0002] A residual current circuit breaker (RCCB), or residual current device (RCD), is an electrical safety device that automatically switches off an electricity supply when an earth leakage at a harmful level is detected. An RCCB provides personal protection from electric shock and helps prevent domestic and workplace injuries and fatalities.

[0003] RCCBs come in many forms and configurations. For example, a small compact low-voltage RCCB, frequently referred to as a miniature circuit breaker (MCB) type RCCB, is commonly used in many situations. An RCCB that is configured to additionally provide overcurrent protection is frequently referred to as an RCCBO.

[0004] An RCCB comprises neutral and live conductors that connect a "line side" of the RCCB to a "load side". In use, the line side is connected to a mains supply of electricity and the load side is connected to an electrical circuit that supplies power to one or more electrical devices. For example, the load side may be connected to a final sub-circuit of a domestic, commercial or industrial power supply.

[0005] The neutral and live conductors of an RCCB are arranged such that they either pass through or are wound around a ferrite toroid inside of the device. The RCCB constantly monitors the vectorial sum of the currents flowing through the neutral and live conductors around the toroid. In normal conditions, the vectorial sum is zero. However, in the event of an earth leakage, the vectorial sum is non zero which creates a magnetic flux in the toroid. The imbalance is detected by a relay assembly disposed next to the toroid. If the imbalance is higher than a preset threshold value and lasts for more than a preset tripping time value, then the relay assembly triggers a switch assembly that operates to disconnect the RCCB from the mains supply of electricity.

[0006] An RCCB must be periodically tested to ensure that it is operating correctly and in accordance with its functional and operating requirements. An RCCB typically comprises a manual test switch that allows a human operator to simulate an earth leakage. However, this test only allows the operator to confirm that the RCCB is generally responsive to earth leakages. The test does not let the operator measure how quickly the RCCB is responding or the amount of leaked current that causes the RCCB to trip.

[0007] An operator may, therefore, use an external circuit breaker testing device to perform more sophisticated tests on an RCCB. To connect the external testing device, the test leads of the testing device must be manually placed onto the load side terminals of the RCCB. However, a skilled electrician is required to do this and, in many cases, this can only be performed after the escutcheon cover of the switchboard that the RCCB is installed into has been physically removed. This is time consuming, impractical and presents a risk to the operator of receiving an electric shock when performing the connection work and tests.

[0008] In this context, there is a need for improved residual current circuit breakers and methods for testing such devices.

Summary

[0009] According to the present invention, there is provided a residual current circuit breaker comprising: a socket comprising at least first and second apertures configured to receive, removably, respective neutral and live pins of a plug connectable to an external residual current circuit breaker testing device; and first and second conductors configured to connect, electrically, the neutral and live pins of the plug to respective neutral and live conductors of the residual current circuit breaker when the plug is in the socket.

[0010] The socket may be integrally formed in a housing of the residual current circuit breaker.

[0011] The socket may be integrally formed in a front side of the housing.

[0012] The socket may be formed in a receptacle that is separate to a housing of the residual current circuit breaker.

[0013] The receptacle may be configured to be attached to the housing.

[0014] The first conductor may comprise a wire extending between the first aperture and the neutral conductor.

[0015] The second conductor may comprise a wire extending between the second aperture and the live conductor.

[0016] The socket may further comprise a shutter assembly configured to obstruct the second aperture when the plug is removed from the socket to prevent insertion of objects into the second aperture.

[0017] The shutter assembly may comprise: an elongate shutter slidably connected to the residual current circuit breaker and movable between first and second positions; and a biaser for biasing the elongate shutter in the first position when the plug is removed from the socket, wherein a shape of the elongate shutter provides that, in the first position, the elongate shutter obstructs the second aperture and extends partially into the first aperture such that it is caused to be urged towards the second position when the neutral pin of the plug is inserted into the first aperture.

[0018] The elongate shutter may comprise a hole formed in the elongate shutter, wherein the hole is positioned such that: when the elongate shutter is in the first position, the hole is adjacent to the second aperture such that the elongate shutter obstructs the second aperture; and when the elongate shutter is in the second position, the hole is aligned with the second aperture so that it may receive the live pin of the plug.

[0019] The biaser may comprise a helical compression spring.

[0020] The biaser may comprise a torsion spring.

[0021] The socket may comprise a triangle-shaped recess adapted to receive a complementary triangle-shaped plug of a cable leading to the residual current circuit breaker testing device.

[0022] The socket may comprise a rectangular-shaped recess adapted to receive a complementary rectangular-shaped plug of a cable leading to the residual current circuit breaker testing device.

[0023] The residual current circuit breaker may further comprise a manual test switch assembly configured to connect, electrically, the live conductor on a line side of the residual current circuit breaker to the neutral conductor on a load side of the residual current circuit breaker to thereby create an imbalance in the residual current circuit breaker causing it to trip.

[0024] The manual test switch assembly may comprise: a first wire connecting the live conductor of the residual current circuit breaker electrically to the test switch assembly; a second wire connecting the test switch assembly electrically to the neutral conductor of the residual current circuit breaker; and a resistor connected to the second wire for reducing electrical current flowing through the second wire.

[0025] The residual current circuit breaker may further comprise line and load connection points and a toggle switch assembly configured to form an electrical connection between, selectively: the first aperture of the socket and a neutral conductor of either the line or the load connection point; and the second aperture of the socket and a live conductor of either the line or the load connection point.

[0026] The toggle switch assembly may further be configured such that the first and second apertures of the socket may be disconnected selectively from both the line and load connection points.

[0027] The present invention also provides a testing device assembly for the residual current circuit breaker, wherein the testing device assembly comprises: a cable for connecting the testing device assembly to the residual current circuit breaker; and a plug disposed at an end of the cable, wherein the plug is configured to connect into the socket of the residual current circuit breaker and comprises: a live pin; and a neutral pin comprising a tapered peripheral end configured such that when inserted into the first aperture of the socket of the residual current circuit breaker the peripheral end causes the elongate shutter of the shutter assembly to slide towards the second position.

[0028] The plug of the testing device assembly may further comprise a fuse disposed directly behind the live pin of the plug.

[0029] The residual current circuit breaker may be a multi-phase residual current circuit breaker comprising first, second and third phase live conductors, and wherein the socket further comprises: third and fourth apertures; and third and fourth conductors, wherein the second, third and fourth conductors are configured to connect electrically the second, third and fourth apertures to, respectively, the first, second and third phase live conductors.

[0030] The present invention also provides a multi-phase residual current circuit breaker comprising: a neutral conductor; first, second and third phase live conductors; first, second and third sockets each being configured to receive a plug of a cable connectable to an external residual current circuit breaker testing device; first, second and third conductors configured to connect, electrically, a live pin of the plug to, respectively, the first, second or third phase live conductor when the plug is plugged into, respectively, the first, second or third socket; and fourth, fifth and sixth conductors configured to connect, electrically, a neutral pin of the plug to the neutral conductor when the plug is plugged into, respectively, the first, second or third socket.

[0031] The present invention also provides a method of testing a residual current circuit breaker, wherein the method comprises: forming a socket in the residual current circuit breaker, wherein the socket is configured to receive a plug of a cable connected to an external residual current circuit breaker testing device; installing first and second conductors into the residual current circuit breaker such that an electrical connection is established between neutral and live pins of the plug and, respectively, neutral and live conductors of the residual current circuit breaker when the plug is inserted into the socket; inserting the plug into the socket; and using the external testing device to cause electrical current flowing from the live pin of the plug to the external testing device to flow to earth to thereby simulate an earth leakage and cause the residual current circuit breaker to trip.

[0032] The method may further comprise forming the socket in a front side of a housing of the residual current circuit breaker.

[0033] The method may further comprise forming the socket in a receptacle that is separate to a housing of the residual current circuit breaker.

[0034] The method may further comprise attaching the receptacle to the housing of the residual current circuit breaker.

[0035] The method may further comprise using the external testing device to measure an elapsed time between: when the electrical current flowing from the live pin to the external testing device is caused to flow to earth; and when the residual current circuit breaker trips.

[0036] The method may further comprise using the external testing device to measure the amount of electrical current that causes the residual current circuit breaker to trip.

[0037] The present invention also provides a method of testing a multi-phase residual current circuit breaker, wherein the multi-phase residual current circuit breaker comprises a neutral conductor and first, second and third phase live conductors, the method comprising: forming a socket in the multi-phase residual current circuit breaker, wherein the socket is configured to receive a plug of a cable connected to an external residual current circuit breaker testing device, and wherein the socket is configured to receive the plug in one of three positions and comprises a first aperture configured to receive a neutral pin of the plug and second, third and fourth apertures each configured to receive a live pin of the plug when the plug is inserted in one of the three positions; installing conductors into the multi-phase residual current circuit breaker that connect the neutral pin of the plug to the neutral conductor and the live pin of the plug to the first, second or third phase live conductors when the plug is inserted in, respectively, first, second and third of the three positions; inserting the plug into the socket in one of the three positions; and using the external testing device to cause electrical current flowing from the live pin of the plug to the multi-phase external testing device to flow to earth to thereby simulate an earth leakage and cause the multi-phase residual current circuit breaker to trip.

[0038] The present invention also provides a method for testing a multi-phase residual current circuit breaker, wherein the multi-phase residual current circuit breaker comprises a neutral conductor and first, second and third phase live conductors, the method comprising: forming first, second and third sockets into the multi-phase residual current circuit breaker, each of the sockets being configured to receive a plug of a cable connectable to an external residual current circuit breaker testing device; installing first, second and third conductors into the multi-phase residual current circuit breaker, wherein the conductors are configured to connect, electrically, a live pin of the plug to, respectively, the first, second or third phase live conductor when the plug is plugged into, respectively, the first, second or third socket; installing fourth, fifth and sixth conductors into the multi-phase residual current circuit breaker, wherein the fourth, fifth and sixth conductors are configured to connect, electrically, a neutral pin of the plug to the neutral conductor when the plug is plugged into, respectively, the first, second or third socket; inserting the plug into the first, second or third socket; and using the external testing device to cause electrical current flowing from the live pin of the plug to the multi-phase external testing device to flow to earth to thereby simulate an earth leakage and cause the multi-phase residual current circuit breaker to trip.

Brief Description of Drawings

[0039] Embodiments of the invention will now be described by way of example only with reference to the accompanying drawings, in which: Figures 1(a) and 1(b) are, respectively, front and side views of a single-phase residual current circuit breaker according to an example embodiment of the invention; Figures 2(a) and 2(b) are enlarged partial front views of an example socket of the single-phase residual current circuit breaker of Figures 1(a) and 1(b); Figure 3 is a partial cutaway side view of the example socket of Figures 2(a) and 2(b) arranged next to an example plug connectable to an external residual current circuit breaker testing device; Figure 4 is an isometric view of a cable of an external residual current circuit breaker testing device assembly comprising the plug depicted in Figure 3; Figure 5 is a circuit diagram of internal circuitry that may be comprised in the single-phase residual current circuit breaker of Figures 1(a) and 1(b); Figure 6 is an enlarged partial front view of another example socket that may be comprised in a residual current circuit breaker in embodiments of the invention; Figure 7 is a circuit diagram of internal circuitry that may be comprised in a single-phase residual current circuit breaker according to a further example embodiment of the invention; Figures 8(a) and 8(b) are enlarged partial front views of an example socket of a multi-phase residual current circuit breaker according to a further example embodiment of the invention;

Figure 9 is a partial cutaway side view of the example socket of Figures 8(a) and 8(b) arranged next to an example plug connectable to an external residual current circuit breaker testing device; and Figure 10 is a circuit diagram of internal circuitry that may be comprised in a multi-phase residual current circuit breaker according to a further example embodiment of the invention.

Description of Embodiments

[0040] Referring to the Figures, an example embodiment of the present invention provides a residual current circuit breaker 10 comprising a socket 12 comprising at least first 14 and second 16 apertures configured to receive, removably, respective neutral 18 and live 20 pins of a plug 22, wherein the plug 22 is connectable to an external residual current circuit breaker testing device (not shown). The circuit breaker 10 further comprises first 24 and second 26 conductors configured to connect, electrically, the neutral and live pins 18,20 of the plug 22 to respective neutral 28 and live 30 conductors of the circuit breaker 10 when the plug 22 is plugged into the socket 12.

[0041] More particularly, the socket 12 may be formed integrally in a front side 32 of the housing of the circuit breaker 10. In the example depicted in Figures 1(a) and (b), the size, dimensions and operating parameters of the circuit breaker 10 are such that the device may be classified as being a MCB-type residual current circuit breaker.

[0042] The circuit breaker 10 comprises an integrated manual test switch assembly 34 on a front side of the circuit breaker 10 that is configured to allow a human operator to simulate an earth leakage and trip the circuit breaker 10 manually. The socket 12 may be formed in a front-facing panel 36 of the circuit breaker 10 housing disposed immediately below the test switch assembly 34.

[0043] Referring to Figure 5, the first conductor 24 may comprise a wire 38 extending between the first aperture 14 and the neutral conductor 28. The second conductor 26 may comprise a further wire 40 extending between the second aperture 16 and the live conductor 30. The two wires 38,40 ensure that, when the plug 22 is plugged into the socket 12, an electrical connection is established between the neutral and live pins 18,20 of the plug 22 and, respectively, the neutral and live conductors 28,30.

[0044] Referring to Figure 3, the neutral pin 18 of the plug 22 may be longer than the live pin 20. The pins 18,20 may each have tapered peripheral ends that form a point. The socket 12 may further comprise a shutter assembly 42 configured to obstruct at least the second aperture 16 when the plug 22 is removed from the socket 12 to prevent the live pin 20, and any other objects, from being inserted into the second aperture 16.

[0045] The shutter assembly 42 may comprise an elongate shutter 44 that is slidably connected to a housing of the circuit breaker 10 and is movable between a first and a second position. The shutter assembly 42 may further comprise a biaser 46 for biasing the elongate shutter 44 in the first position when the plug 22 is removed from the socket 12. In the example depicted in Figure 3, the biaser 46 comprises a flexible strip 48 disposed between a topmost end of the elongate shutter 44 and a topmost internal cavity wall 49 of the socket 12 housing. Stored energy in the strip 48 exerts a downwards force on the elongate shutter 44 causing it to be pushed towards, and at least partially into, the first aperture 14.

[0046] In other examples, the biaser 46 may comprise a helical compression spring or a torsion spring similarly configured to exert a downwards force on the elongate shutter 44. The biaser 46 may be made of metal, stiff plastic or a similar appropriate material.

[0047] In the Figures, the elongate shutter 44 is shown arranged in its first position. In this position, the elongate shutter 44 extends transversely across the internal elongate cavity formed by the second aperture 16. This forms an obstruction in the elongate cavity which prevents the live pin 20 of the plug 22, and any other objects, from being inserted into the second aperture 16. Further, when in the first position, a lowermost end of the elongate shutter 44 extends partially into the cavity formed by the first aperture 14. In this configuration, the elongate shutter 44 is urged in an upwards direction by the neutral pin 18 of the plug 22 when the plug 22 is inserted into the socket 12 and the neutral pin 18 is pushed through the first aperture 14.

[0048] The elongate shutter 44 may further comprise a hole 50 formed transversely through the elongate shutter 44. The hole 50 is positioned such that when the elongate shutter 44 is arranged in the first position, as depicted in the Figures, the hole 50 is offset from the second aperture 16 so that the elongate shutter 44 is caused to occupy the second aperture 16 thereby forming an obstruction. When the elongate shutter 44 is urged into its second position by the neutral pin 18, the hole 50 becomes aligned with the second aperture 16. The second aperture 16, therefore, becomes substantially unobstructed and may receive the live pin 20 of the plug 22.

[0049] As depicted in Figures 2(a) and (b), the shutter assembly 42 may further comprise a second elongate shutter 51 configured to slide movably between a first position and a second position. In the first position, the shutter 51 partially occupies the first aperture 14. In the second position, the shutter 51 does not occupy the first aperture 14. The shutter 51 is configured such that it is urged into its second position by the neutral pin 18 of the plug 22 when the plug 22 is inserted into the socket 12.

[0050] In addition to the shutter assembly 42, in other examples the circuit breaker 10 may comprise a protective panel (not shown) that is hingedly connected to the housing of the circuit breaker 10 and configured to cover both apertures 14,16 of the socket 12 when the socket 12 is not being used. When a test needs to be performed, the panel may be flipped open to expose the apertures 14,16 so that the plug 22 may be inserted.

[0051] The socket 12 may comprise a triangle-shaped recess 52 formed in a surface of the circuit breaker 10 housing. The recess 52 may be adapted such that the socket 12 is configured to receive, removably, a complementary triangle-shaped plug 22, as shown in Figure 4, connected to the external residual current circuit breaker testing device.

[0052] Referring to Figure 6, in another example the socket 12 may comprise a rectangular-shaped recess 54 formed in a surface of the circuit breaker 10 housing. The recess 54 may be adapted such that the socket 12 is configured to receive, removably, a complementary rectangular-shaped plug (not shown) that is connectable to an external residual current circuit breaker testing device. It will be understood that the rectangular shape of the recess 54 is, advantageously, space efficient. This, accordingly, enables the socket 12 to be incorporated into single-phase residual current circuit breaker devices that are small and only have limited room available for such modifications.

[0053] In other examples, the socket 12 may be formed in a device, unit or similar receptacle (not shown) that is separate to the principal housing of the circuit breaker 10. The receptacle may be placed next to the housing on the electrical switchboard that the circuit breaker 10 is installed in. Alternatively, the receptacle may be configured such that it attaches onto the housing of the circuit breaker 10 and effectively forms an extension to the housing. In such examples, it will be appreciated that the first 24 and second 26 conductors extend from the socket 12 formed in the receptacle into the housing of the circuit breaker 10 and to the neutral 28 and live 30 conductors of the circuit breaker 10.

[0054] In use, when the circuit breaker 10 needs to be tested, an external residual current circuit breaker testing device may be connected to the circuit breaker 10. Figure 4 depicts an example cable 56 that may be used to establish the connection. The cable 56 comprises the triangular-shaped plug 22 at one end for engaging with the socket 12 on the circuit breaker 10. A socket 58 at an opposite end of the cable 56 is configured to receive a standard mains-type plug of the external testing device. The cable 56 may also comprise an earth lead 60. The earth lead 60 may have an alligator clip, or a similar conductive fastening means, disposed at its end (not shown) for attaching the earth lead 60 to an object that is grounded to earth. In other examples, the earth lead may have a plug at its end provided with an earth pin (not shown) for connecting to an aperture of a socket connected to earth.

[0055] As shown in Figure 3, the plug 22 may further comprise a fuse 61 connected between the live pin 20 of the plug 22 and a live wire of the cable 56 (not shown). The fuse 61 advantageously provides for short circuit protection and removes the need for fuse protection to be provided inside the circuit breaker 10. The fuse 61 may be disposed directly behind the live pin 20 to provide for optimal protection. In other examples, however, the plug 22 may not comprise the fuse 61 and, instead, a fuse may be included directly in the circuit breaker 10 configured to provide short circuit protection.

[0056] It will be understood that immediately before the plug 22 has been inserted into the socket 12, the biaser 46 provides that the elongate shutter 44 of the socket 12 is disposed in its first position. In this position, the elongate shutter 44 seals off the second aperture 16 and extends partially into the first aperture 14. When the plug 22 is pushed into the socket 12, because the neutral pin 18 of the plug 22 is longer than the live pin

, the neutral pin 18 enters the first aperture 14 of the socket 12 before the live pin 20 enters the second aperture 16. As the neutral pin 18 enters, its tapered peripheral end comes into contact with the lower end of the elongate shutter 44 in the first aperture 14. This causes the elongate shutter 44 to, in turn, slide upwards towards its second position.

[0057] Once the tapered end of the neutral pin 18 has been pushed completely past the lower end of the elongate shutter 44 in the first aperture 14, the elongate shutter 44 will then be in its second position such that the hole 50 of the elongate shutter 44 is aligned with the second aperture 16. This allows the live pin 20 of the plug 22 to be pushed into the second aperture 16 to fully connect the plug 22 to the socket 12.

[0058] An operator may then use the external testing device to perform one or more tests on the circuit breaker 10. In one example, the operator may use the testing device to simulate an earth leakage and cause the circuit breaker 10 to trip. To perform this test, the operator presses a button or similar control device on the testing device that causes an electrical connection to be established, via the testing device, between the live pin 20 of the plug 22 and earth. Referring to the example internal circuitry 61 of the circuit breaker 10 shown in Figure 5, establishing this connection, in turn, causes the second aperture 16, the second conductor 26 and the live conductor 30 of the circuit breaker 10 to be connected to earth. This causes an imbalanced magnetic field in a ferrite toroid 62 of the circuit breaker 10 that is detected by a relay assembly 64. The relay assembly 64 operates a switch 66 that disconnects the neutral and live conductors 28,30 from the mains supply of electricity feeding into the circuit breaker 10 to trip the circuit breaker 10.

[0059] In another example, the operator may use the external testing device to measure the amount of time that elapses between the point in time when the electrical connection is established between the live pin 20 of the plug 22 and earth and when the circuit breaker 10 actually trips. Residual current circuit breakers are normally required to trip within certain time periods. For example, in domestic situations they are normally required to trip within 300 milliseconds (ms). The external testing device may allow the operator to confirm that the circuit breaker 10 is performing within these limits.

[0060] In another example, the operator may use the external testing device to obtain an accurate measurement of the amount of current imbalance in the circuit breaker 10 that causes it to trip. This is commonly required to be 30 milliamps (mA) for MCB-type residual current circuit breakers.

[0061] When all tests have been completed, the plug 22 may then be removed from the circuit breaker 10. The biaser 46 causes the elongate shutter 44 to then slide downwards back into its first position so that it forms an obstruction preventing objects from being inserted into the second aperture 16 of the socket 12.

[0062] The socket 12 advantageously enables a wide range of sophisticated external testing devices to be connected to the circuit breaker 10 conveniently with minimal interference. In particular, a connection may be established, and the tests performed, without having to remove the escutcheon cover of the switchboard that the circuit breaker 10 is installed into and without any complicated wiring having to be completed.

[0063] Further, in examples where the socket 12 is disposed on a front side of the circuit breaker 10, external testing devices can advantageously be connected to the socket 12 even when the circuit breaker 10 is installed into a crowded electrical switchboard with minimal space available for diagnostic and testing devices.

[0064] For simple trip tests that do not require the sophisticated functionality or sensitivity of an external testing device, an operator may, alternatively, use the integrated manual test switch assembly 34 of the circuit breaker 10 to verify that the circuit breaker 10 is generally responsive to earth leakages. As shown in Figure 5, the test switch assembly 34 may comprise a first wire 72 connecting the live conductor 30 on a line side of the circuit breaker 10, electrically, to the test switch assembly 34, a second wire 74 connecting the test switch assembly 34, electrically, to the neutral conductor 28 on a load side of the circuit breaker 30 and a resistor 76 connected to the second wire 74 for reducing electrical current flowing through the second wire 74.

[0065] Operating the test switch assembly 34 causes an electrical connection to be established between the live and neutral conductors 30,28 via the test switch assembly 34. This causes an imbalance in the ferrite toroid 62 that causes the circuit breaker 10 to trip.

[0066] In examples where the socket 12 is formed in a front-facing panel 36 of the circuit breaker 10 below the test switch assembly 34, the socket 12 advantageously occupies a relatively small amount of surface area on the panel 36. The socket 12 does not, therefore, interfere with the normal operation of the test switch assembly 34.

[0067] It will be understood that commercially available residual current circuit breakers commonly comprise a line connection point (or a line side) and a load connection point (or a load side). In use, the line connection point is connected to the mains supply of electricity that feeds into the circuit breaker. The load connection point is connected to the circuit that supplies the final sub-circuit that the circuit breaker is designed to protect. Many circuit breakers are configured so that they are "one way" only and will only operate correctly if their respective line and load connection points are connected the right way around. However, some circuit breakers are "two way" and will operate correctly regardless of which way around they are installed.

[0068] To accommodate such two-way functionality, referring to Figure 7 there is shown a circuit diagram of further example internal circuitry 80 that may be comprised in the single-phase residual current circuit breaker 10. It will also be understood that the same two-way functionality may be incorporated equally into three-phase residual current circuit breaker devices.

[0069] In Figure 7, the line and load sides of the circuit breaker 10 are referred to generally by reference numerals 82 and 84 respectively. The neutral conductor 28 of the circuit breaker 10 comprises a line-side portion 68 and a load-side portion 86. Similarly, the live conductor 30 of the circuit breaker 10 comprises a line-side portion 70 and a load-side portion 88.

[0070] The internal circuitry 80 further comprises a toggle switch assembly 90. The toggle switch assembly 90 is configured to form an electrical connection between the first aperture 14 of the socket 12 and, selectively, either the line-side portion 68 or the load-side portion 86 of the neutral conductor 28. The toggle switch assembly 90 is also configured to form an electrical connection between the second aperture 16 of the socket 12 and, selectively, either the line-side portion 70 or the load-side portion 88 of the neutral conductor 30.

[0071] In use, when the circuit breaker 10 is being installed into a switchboard, the toggle switch assembly 90 may be operated by the person performing the installation so that the socket 12 is wired to the line and load sides 82,84 of the internal circuitry 80 correctly according to which way around the circuit breaker 10 is to be installed. This advantageously enables external testing devices to be connected to the socket 12 and perform correctly regardless of which way around the circuit breaker 10 is installed. The installer simply needs to set the toggle switch assembly 90 accordingly.

[0072] The toggle switch assembly 90 may be mechanically operated to allow either the line or load-side connection point 82,84 to be tested selectively. In one example, the toggle switch assembly 90 may be configured such that a connection is established automatically between the line or load-side connection point 82,84 (as required) when the plug 22 is inserted into the socket 12 (for example, when the neutral pin 18 enters the first aperture 14). In other examples, the toggle switch assembly 90 may be electrically operated so that the operator is able to make the required setting using a separate control mechanism, remotely or locally connected to the toggle switch assembly 90, for safety and convenience.

[0073] The toggle switch assembly 90 may also be configured such that the first and second apertures 14,16 of the socket 12 may be disconnected altogether from both the line and load-side connection points 82,84. This advantageously allows an operator to disable the socket 12 when the circuit breaker 10 is not being tested for safety reasons. The operator may re-establish a connection only when the circuit breaker 10 needs to be tested.

[0074] The toggle switch assembly 90 may also be configured so that it defaults to the disconnected state, automatically, when not in use.

[0075] Referring to Figures 8(a) and (b), there is shown an example socket 90 that may be comprised in a multi-phase residual current circuit breaker according to a further example embodiment of the invention. The socket 90 is, more particularly, a three-way socket adapted for use with a three-phase residual current circuit breaker.

[0076] The socket 90 may comprise a recess 91 having a cross-sectional shape that is substantially triangular. The socket 90 may further comprise a first aperture 92 disposed substantially centrally within the recess 91. The socket 90 may also comprise second, third and fourth apertures 94, 96, 98 disposed at respective corners of the triangular recess 91.

[0077] The socket 90 may further comprise a shutter assembly that comprises first, second and third elongate shutters 100, 102, 104 each slidably connected to the circuit breaker 90 and being movable between first and second positions. The elongate shutters 100, 102, 104 may each comprise a hole 106.

[0078] The elongate shutters 100, 102, 104 are configured such that, when arranged in their respective first positions, their peripheral ends protrude into the central first aperture 92 and their holes 106 are out of alignment with the second, third and fourth apertures 94, 96, 98 of the socket 90.

[0079] As shown in Figure 9, the socket 90 may further comprise biasers 108 configured to bias the elongate shutters 100, 102, 104 in their respective first positions.

[0080] The socket 90 may be configured to receive a plug 110 of a cable of an external residual current testing device (not shown). The plug 110, which is shown in partial cross-section in Figure 9, may be triangular in shape and be substantially identical in form and configuration to the example plug 22 shown in Figure 4.

[0081] The plug 110 may comprise a single neutral pin 112 and a single live pin 114 adapted such that the plug 110 may be inserted into the socket 90 in one of three different configurations. In the first configuration, the live pin 114 is inserted into the first aperture 94 of the socket 90. In the second configuration, the live pin 114 is inserted into the second aperture 96 of the socket 90. In the third configuration, the live pin 114 is inserted into the third aperture 98 of the socket 90. The neutral pin 112 of the plug 110 is inserted into the first aperture 92 of the socket 90 in all three of the configurations. The plug 110 is inserted into the socket 90 according to the first, second or third configuration depending on whether the first, second or third phase of the circuit breaker, respectively, needs to be tested.

[0082] The plug 110 may also comprise a fuse 116 disposed directly behind the live pin 114 of the plug 110.

[0083] In use, the plug 110 is inserted into the socket 90 in accordance with one of the three available configurations. Because the neutral pin 112 is longer than the live pin 114, the neutral pin 112 enters the first aperture 92 before the live pin 114 can enter the relevant aperture 94, 96, 98 corresponding to the chosen configuration. As the neutral pin 112 enters, its peripheral end, which is tapered and forms a point, urges the elongate shutters 100,102,104 apart from one another into their respective second positions such that their holes 106 are aligned with, respectively, the first, second and third apertures 94, 96, 98 of the socket 90. This allows the live pin 114 of the plug 110 to enter the aperture 94, 96, 98 corresponding to the chosen configuration so that the plug 110 may then be inserted fully into the socket 90.

[0084] Figure 10 shows example internal circuitry 120 that may be comprised in the multi-phase residual current circuit breaker. The internal circuitry 120 may comprise a first conductor 122 for connecting, electrically, the first aperture 92 of the socket 90 to a neutral conductor 124 of the internal circuitry 120. The first conductor 122 ensures that an electrical connection is established between the neutral pin 112 of the plug 110 and the neutral conductor 124 when the plug 110 is inserted into the socket 90 in any one of the three available configurations.

[0085] The internal circuitry 120 may further comprise second, third and fourth conductors 126, 128, 130 for connecting, electrically, the second, third and fourth apertures 94, 96, 98 of the socket 90 to, respectively, first, second and third live-phase conductors 132, 134, 136 of the internal circuitry 120. The conductors 126, 128, 130 ensure that the live pin 114 of the plug 110 is connected, electrically, to the relevant first, second or third live-phase conductor 132, 134, 136 that corresponds to the chosen configuration when the plug 110 is inside the socket 90.

[0086] The socket 90 advantageously allows the external testing device to be used to test each of the three phases of the internal circuitry 120 individually. To test the first phase, the plug may be inserted into the socket 90 so that its live pin 114 is in the second aperture 94. To test the second phase, the plug may be inserted into the socket so that its live pin 114 is in the second aperture 96. To test the third phase, the plug may be inserted into the socket 90 so that its live pin 114 is in the second aperture 98.

[0087] It will be understood that when the plug 110 is connected into the socket 90 and one of the three phases is being tested, two of the three apertures 94, 96, 98 will not be in use. The triangular shape of the socket 90 and the plug 110 advantageously provide that the apertures not in use are covered by the plug 110 during testing which stops objects from being inserted into them.

[0088] Further, after an individual live phase has been tested, if a further live phase needs to be tested the plug 110 may, advantageously, be removed from the socket 90, rotated and then inserted back into the socket 90 in the relevant configuration that corresponds to the further live phase.

[0089] While the three-way socket 90 depicted in Figures 8(a) and (b) and Figure 9 is adapted for use, in particular, with three-phase residual current circuit breakers, it will be understood that the socket 90 may be incorporated into single-phase residual current circuit breakers in the event that it is more economically viable to manufacture only one version equally useable in both situations. In such examples, the socket 90 may be incorporated with only one of its second, third and fourth apertures 94, 96, 98 (for example, only the second aperture 94) connected to the single live phase of the circuit breaker.

[0090] In another example of the invention, in lieu of the three-way socket 90, a three-phase residual current circuit breaker may be provided with three individual sockets (not shown) formed in the circuit breaker for testing, respectively, the first, second and third phases of the circuit breaker. Each of the three sockets may comprise a first and a second aperture configured to receive, respectively, a neutral and a live pin of a plug connected to an external testing device. The three sockets may each be configured to connect the neutral pin of the plug to the neutral conductor of the circuit breaker when the plug is in the socket. The three sockets may also each be configured to connect the live pin of the plug to a relevant first, second or third phase live conductor of the circuit breaker when the plug is inserted therein.

[0091] Embodiments of the present invention provide residual current circuit breakers capable of being tested conveniently using external testing devices.

[0092] For the purpose of this specification, the word "comprising" means "including but not limited to", and the word "comprises" has a corresponding meaning.

[0093] The above embodiments have been described by way of example only and modifications are possible within the scope of the claims that follow.

Claims

1. A residual current circuit breaker, comprising: a housing adapted to be installed in an electrical switchboard of a building or facility; neutral and live conductors disposed inside of the housing, wherein each of the conductors is electrically connected to a line side and to a load side of the residual current circuit breaker, the line side being electrically connectable to an external power source supplying electrical power to the electrical switchboard and the load side being electrically connectable to an internal power distribution circuit of the building or facility; a socket provided with the housing, wherein the socket comprises at least first and second apertures that removably receive, respectively, neutral and live pins of a plug connectable to an external residual current circuit breaker testing device; and first and second conductors configured to connect electrically the neutral and live pins of the plug to the neutral and live conductors when the plug is in the socket.

2. The residual current circuit breaker according to claim 1, wherein the socket is integrally formed in the housing of the residual current circuit breaker.

3. The residual current circuit breaker according to claim 2, wherein the socket is integrally formed in a front side of the housing.

4. The residual current circuit breaker according to claim 1, wherein the socket is formed in a receptacle that is separate and attachable to the housing.

5. The residual current circuit breaker according to any one of the preceding claims, wherein: the first conductor comprises a wire extending between the first aperture and the neutral conductor; and the second conductor comprises a wire extending between the second aperture and the live conductor.

6. The residual current circuit breaker according to any one of the preceding claims, wherein the socket further comprises a shutter assembly configured to obstruct the second aperture when the plug is removed from the socket to prevent insertion of objects into the second aperture.

7. The residual current circuit breaker according to claim 6, wherein the shutter assembly comprises: an elongate shutter slidably connected to the residual current circuit breaker and movable between first and second positions; and a biaser for biasing the elongate shutter in the first position when the plug is removed from the socket, wherein a shape of the elongate shutter provides that, in the first position, the elongate shutter obstructs the second aperture and extends partially into the first aperture such that the elongate shutter is caused to be urged towards the second position by the neutral pin of the plug when the neutral pin is inserted into the first aperture.

8. The residual current circuit breaker according to claim 7, wherein the elongate shutter comprises a hole formed in the elongate shutter, wherein the hole is positioned such that: when the elongate shutter is in the first position, the hole is adjacent to the second aperture such that the elongate shutter obstructs the second aperture; and when the elongate shutter is in the second position, the hole is aligned with the second aperture so that the second aperture may receive the live pin of the plug.

9. The residual current circuit breaker according to any one of the preceding claims, wherein the residual current circuit breaker further comprises line and load connection points and a toggle switch assembly configured to form an electrical connection between, selectively: the first aperture of the socket and a neutral conductor of either the line or the load connection point; and the second aperture of the socket and a live conductor of either the line or the load connection point.

10. The residual current circuit breaker according to claim 9, wherein the toggle switch assembly is further configured such that the first and second apertures of the socket may be disconnected selectively from both the line and load connection points.

11. The residual current circuit breaker according to any one of the preceding claims, wherein the residual current circuit breaker is a multi-phase residual current circuit breaker comprising first, second and third phase live conductors, and wherein the socket further comprises: third and fourth apertures; and third and fourth conductors, wherein the second, third and fourth conductors are configured to connect electrically the second, third and fourth apertures to, respectively, the first, second and third phase live conductors.

12. A multi-phase residual current circuit breaker, comprising: a housing adapted to be installed in an electrical switchboard of a building or facility; a neutral conductor disposed inside of the housing, wherein the neutral conductor is electrically connected to a line side and to a load side of the multi-phase residual current circuit breaker, the line side being electrically connectable to an external power source supplying electrical power to the electrical switchboard and the load side being electrically connectable to an internal power distribution circuit of the building or facility; first, second and third phase live conductors disposed inside of the housing, wherein each of the live conductors is electrically connected to the line side and to the load side of the multi-phase residual current circuit breaker; first, second and third sockets provided with the housing, each of the sockets being configured to receive a plug of a cable connectable to an external residual current circuit breaker testing device; first, second and third conductors configured to connect electrically a live pin of the plug to, respectively, the first, second or third phase live conductor when the plug is plugged into, respectively, the first, second or third of the sockets; and fourth, fifth and sixth conductors configured to connect, electrically, a neutral pin of the plug to the neutral conductor when the plug is plugged into, respectively, the first, second or third of the sockets.

13. A testing device assembly for a residual current circuit breaker, wherein the residual current circuit breaker is according to any one of claims 7 to 10, and wherein the testing device assembly comprises: a cable for connecting the testing device assembly to the residual current circuit breaker; and a plug disposed at an end of the cable being configured to connect into the socket of the residual current circuit breaker and comprising: a live pin; and a neutral pin comprising a tapered peripheral end configured such that when inserted into the first aperture of the socket of the residual current circuit breaker the tapered peripheral end causes the elongate shutter of the shutter assembly to slide towards the second position.

14. The testing device assembly of claim 13, wherein the plug of the testing device assembly further comprises a fuse disposed directly behind the live pin of the plug.

15. A method of testing a residual current circuit breaker, the residual current circuit breaker being adapted to be installed in an electrical switchboard of a building or facility, wherein the method comprises: forming a socket in a housing of the residual current circuit breaker, wherein the socket is configured to receive a plug of a cable connected to an external residual current circuit breaker testing device; installing first and second conductors into the housing such that an electrical connection is established between neutral and live pins of the plug and, respectively, neutral and live conductors of the residual current circuit breaker within the housing when the plug is inserted into the socket, wherein each of the neutral and live conductors is electrically connected to a line side and to a load side of the residual current circuit breaker, wherein the line side is electrically connectable to an external power source supplying electrical power to the electrical switchboard and the load side is electrically connectable to an internal power distribution circuit of the building or facility; inserting the plug into the socket; and using the external residual current circuit breaker testing device to cause electrical current flowing from the live pin of the plug to the external testing device to flow to earth to thereby simulate an earth leakage and cause the residual current circuit breaker to trip.

16. The method according to claim 15, wherein the method comprises forming the socket in a front side of a housing of the residual current circuit breaker.

17. The method according to claim 15, wherein the method comprises forming the socket in a receptacle that is separate to a housing of the residual current circuit breaker.

18. The method according to claim 17, wherein the method further comprises attaching the receptacle to the housing of the residual current circuit breaker.

19. The method according to any one of claims 15 to 18, wherein the method further comprises using the external residual current circuit breaker testing device to measure an elapsed time between: when the electrical current flowing from the live pin to the external testing device is caused to flow to earth; and when the residual current circuit breaker trips.

20. The method according to any one of claims 15 to 19, wherein the method further comprises using the external residual current circuit breaker testing device to measure an electrical current that causes the residual current circuit breaker to trip.