GB2615893A

GB2615893A - Over-current protection for power outlet

Info

Publication number: GB2615893A
Application number: GB2300716.4A
Authority: GB
Inventors: Mazzullo Adrian; Van Zyl Brian
Original assignee: Power Logic South Africa Pty Ltd
Current assignee: Power Logic South Africa Pty Ltd
Priority date: 2023-01-18
Filing date: 2023-01-18
Publication date: 2023-08-23
Also published as: GB202300716D0

Abstract

An electrical power outlet 10 includes a circuit breaker 28 inside a housing 12 that defines a small reset aperture 34 that can only receive a tool 36. The tool 36 can be used to drive a linkage 38 inside the housing 12 to press a reset switch 32 of the circuit breaker 28, but the linkage 38 includes one or more pins 44 that need to enter the socket recesses 16, 18, 20 before the linkage 38 can slide to press the reset switch 32. When an electrical plug is received in the socket 14, its plug pins (figure 1, 22, 24, 26) obstruct the pins 44 of the linkage 38, so that the circuit breaker 28 can only be reset once the plug is removed. The linkage 38 is biased away from the reset switch 32, so that the tool 36 must be used to reset the breaker 28.

Description

OVER-CURRENT PROTECTION FOR POWER OUTLET

FIELD OF THE INVENTION

This invention relates to power outlets suitable for domestic and light commercial environments with trip-free over-current protection that can be reset.

BACKGROUND TO THE INVENTION

Electrical power supplies are practically always provided with over-current protection (preferably trip-free) and in many instances in domestic and light commercial environments, over-current protection is provided at electrical power outlets -either by choice or to comply with statutory requirements. Other forms of over-current protection can be used, but over-current protection in electrical power outlets usually take forms that can be reset by hand, such as resettable thermal circuit breakers or "reset devices".

Over-current protection devices such as thermal reset devices on electrical power outlets are often easy to reach and reset by hand and can pose the risk that users may reset them (or attempt to reset them) without identifying or rectifying the cause of the over-current. In most instances, the over-current is caused by an electrical fault in a powered appliance or other device that has been plugged into a socket in the power outlet and the prudent response to activated over-current protection, would be to disconnect the electrical device before attempting to reset the over-current protection.

The present invention seeks to provide electrical power outlets with over-current protection for a power socket that cannot be reset while there is an electrical plug in the socket, but that also allows easy visual detection if the over-current protection is activated.

SUMMARY OF THE INVENTION

According to the present invention, there is provided an electrical power outlet comprising: a housing defining at least one electrical socket, said socket including a plurality of socket recesses into which pins of a plug can be inserted; said housing also defining a reset aperture that is large enough to receive a tool, but too small to receive any part of the human body; electrical circuitry configured to make electrical contact with the pins of the plug, when the pins are received in the socket recesses; a trip-free over-current protection device inside the housing, said over-current protection device being configured to allow electrical power supply from the electrical circuitry to the plug when the over-current protection device is in an active state, and to change to a tripped state and disrupt said electrical power supply if the current between said electrical circuitry and said plug exceeds a predetermined limit, said over-current protection device including a reset switch that is operable between a free position and a reset position in which the reset switch resets the over-current protection device from the tripped stated to the active state; and a linkage inside the housing, said linkage defining a switch surface that is connectable to the reset switch, a tool face that is aligned with the reset aperture, and at least one protuberance adjacent at least one of the socket recesses; wherein said linkage is movable between: a reset position in which the protuberance obstructs its adjacent socket recess at least in part, and the switch surface presses the reset switch to its reset position; and a retracted position in which the protuberance is retracted from its adjacent socket recess and the switch surface is retracted to permit the reset switch to be in its free position; said power outlet including a bias that urges the linkage towards the retracted position, said linkage being configured to be urged against the bias to the reset position, when a tool is inserted into the reset aperture and exerts a load on the tool face.

The term "tool" refers to any object that is not part of the human body.

The "free position" of the reset switch is not necessarily exclusively associated with the active state or tripped state of the over-current protection device and in some preferred embodiments, the reset switch remains in the free position while the over-current protection device changes from the active state to the tripped state.

The term "connectable to" includes intermittent or continuous contact, or temporary or permanent attachment, between the switch surface and the reset switch.

The term "aligned" is used broadly to include direct alignment between two or more objects, but also includes indirect alignment e.g. the a tool or reset aperture may be aligned with the tool surface through a pivoting link or other arrangement that changes the direction of alignment.

The switch may be biased to the free condition and the switch surface of the linkage may be in contact with the switch so that the bias urges the switch to the free condition and urges the linkage to the retracted position.

Cross-sectional dimensions of the reset aperture may be less than 2mm.

The over-current protection device may be a thermal circuit breaker.

The electrical power outlet may include at least one visual communication device and electronic circuitry that is configured to detect when the over-current protection device is the tripped state and to activate the visual communication device to show that the over-current protection device is in the tripped state. The electronic circuitry may also be configured to activate the visual communication device to show when the over-current protection device is in the active state and may be configured to activate the visual communication device to display instructions to a user to reset the over-current protection device.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of the present invention, and to show how it may be carried into effect, the invention will now be described by way of non-limiting example, with reference to the accompanying drawings in which: Figure 1 shows a diagrammatic representation of a first embodiment of an electrical power outlet according to the present invention, in use, providing electrical power; Figure 2 shows a diagrammatic representation of the electrical power outlet of Figure 1 with its over-current protection being reset; Figure 3 shows a diagrammatic representation of a second embodiment of an electrical power outlet according to the present invention, with its over-current protection being reset; Figure 4 shows a diagrammatic representation of a third embodiment of an electrical power outlet according to the present invention, with its over-current protection being reset; and Figure 5 shows a diagrammatic representation of a fourth embodiment of an electrical power outlet according to the present invention, with its over-current protection being reset.

DETAILED DESCRIPTION OF THE DRAWINGS

Referring to Figures 1 and 2 of the drawings, a first embodiment of a power outlet according to the present invention is generally identified by reference number 10.

The power outlet 10 has a housing 12 that is shown with a circular face, but in other embodiments of the invention, different shapes of housing can be used. A single standard Type G or BS 1363 electrical socket 14 is defined in the housing 12 which includes a live socket recess 16, a neutral socket recess 18 and an earth socket recess 20 that each has a standard rectangular cross-sectional shape. However, in other embodiments of the invention, the power outlet 10 could include multiple power sockets 14 and the power sockets can have configurations different from Type G. Figure 1 shows the power outlet 10 with a Type G electrical plug engaged in the socket 14, which means that a live pin 22, a neutral pin 24 and an earth pin 26 of the plug has been inserted into the corresponding socket recesses 16,18,20. (The plug is not shown in Figure 1, but the plug pins 22,24,26 are shown in section, each inside its associated socket recess 16,18,20.) Figure 2 shows the power outlet 10 with the plug removed, so there are no plug pins in the socket recesses 16,18,20. Inside the housing 12, the power outlet 10 includes electric circuitry that is configured to make electrical contact with the plug pins 22,24,26 when they are received in the socket recesses 16,18,20, preferably by way of electrical contacts that press against the plug pins, so that electrical power can be supplied from the electrical circuitry to the plug pins, to power an electrical device connected to the plug.

A trip-free over-current protection device is provided inside the housing 12 and the overcurrent protection device is preferably a thermal circuit breaker 28, although other forms of over-current protection could be used. The circuit breaker 28 is configured to allow electrical power supply from the electrical circuitry to the plug pins 22,24,26 when the circuit breaker is in an active state, and to change to a tripped state and disrupt the electrical power supply to the plug pins if the current between the electrical circuitry and the plug pins exceeds a predetermined limit -as would happen in the event of a short-circuit.

The circuit breaker 28 includes a reset switch 30 with a reset button 32 that is operable between a free position and a reset position. The reset switch 30 is preferably configured so that the reset button 32 is in the free position when the circuit breaker 28 is in the active state and the power outlet 10 can be used normally. When an over-current is detected, the circuit-breaker trips, i.e. disrupts power supply to the plug pins 22,24,26, and changes to the tripped state. When the circuit breaker 28 trips, the reset button 32 remains in its free position, but when the reset button is depressed to its reset position, it resets the circuit breaker to its active state. The reset button 32 is preferably biased to its free position by bias means such as a compression spring, elastic element, or the like and after the reset button has been pressed against the bias to its reset position, the bias returns it to its free position. Figure 1 shows the reset switch 30 with the reset button 32 in the free position, protruding from the reset switch, whereas Figure 2 shows the reset button in the reset position in which it has been depressed.

A reset aperture 34 is defined in the housing 12 and in the embodiment shown in Figures 1 and 2, the reset aperture is on a side of the housing, close to the neutral socket 18, but in other embodiments of the invention, the reset aperture can be defined elsewhere on the housing. The reset aperture 34 is too small for any part of the human body enter it but is large enough for a tool to enter and in a preferred embodiment, the reset aperture has cross-sectional dimensions of less than 2mm. The reset aperture 34 can be profiled so that only a tool with a specific cross-sectional profile could pass through the aperture, but in some embodiments, the reset aperture 34 could simply be round and could receive a narrow cylindrical tool 36, such as the end of a paper clip, or the like.

A linkage 38 is provided inside the housing 12 and is configured to move inside the housing between a retracted or rest position and a reset position. The linkage 38 is preferably supported or guided inside the housing 12 and is preferably biased towards the retracted position.

The linkage 38 can take various forms, but it defines a switch surface 40 that is connectable to the reset button 32. In the preferred embodiment, the switch surface 40 of the linkage 38 gently rests against the reset button 32 -or can be spaced from the reset button and can occasionally press against the reset button. In other embodiments of the invention, it is possible that the switch surface 40 of the linkage 38 could be connectable to the reset button 32 in other ways, e.g. it could be attached to the reset button, it could be integrally formed with the reset button, it could press the reset button indirectly via an intermediary component, or the like.

The linkage 38 defines a tool face 42 that is aligned with the reset aperture 34, e.g. it can be (preferably) directly aligned with the reset aperture, or it can be indirectly aligned with the reset aperture with a pivoting linkage, a wedge, or other mechanical transfer mechanism changing the direction by which forces can be transferred between a tool 36 inserted into the reset aperture, and the tool face.

The linkage 38 includes a protuberance in the form of a locking pin 44 that is adjacent the neutral socket recess 18 in the embodiment shown in Figures 1 and 2. In other embodiments of the invention, the linkage may include multiple locking pins and/or locking pins adjacent other socket recesses -as will be discussed below. A pin aperture 46 is defined in the wall of the neutral socket recess 18, through which the locking pin 44 can pass.

Figure 1 shows the linkage 38 in its retracted or rest position in which the locking pin 44 is retracted from the neutral socket recess 18, so that the neutral plug pin 24 can be received in the neutral socket recess. The switch surface 40 is sufficiently retracted from the reset button 32 to allow the reset button to be in its free position. In Figure 1 this state of the power outlet 10 is shown with the reset button 32 in its free position and the switch surface 40 in contact with the reset button, but in some embodiments the switch surface may be spaced away from the reset button. When the linkage 38 is in its rest position, the tool surface 42 is immediately adjacent the reset aperture 34 as shown in Figure 1, but in other embodiments of the invention, the tool surface can be set back further into the housing 10, from the reset aperture.

Figure 2 shows the linkage 38 in its reset position in which the tool 36 has been used to press against the tool surface in a longitudinal direction, as shown by the arrow in Figure 2 to slide the linkage from its rest position to its reset position. The tool 36 is shown outside the housing 12 in Figure 2, although part of the tool would need to pass through the reset aperture 34 to slide the linkage 38 to the reset position. When the linkage 38 slides to its reset position, the locking pin 44 slides through the pin aperture 46 to protrude into the neutral socket recess 18 to obstruct the socket recess at least partly. Further, when the linkage 38 slides to its reset position, the switch surface 40 presses against the button 32 and depresses the reset button to its reset position.

The bias of the reset button 32, which urges the reset button to its free position, could serve as a bias that also urges the linkage 38 to its rest (retracted) position. Instead, or in addition, a separate bias such as a spring could be provided to urge the linkage 38 to its rest position. When the tool 36 is inserted into the reset aperture 34 and presses on the tool face 42, it urges the linkage 38 against the bias to the reset position and when the tool is retracted, the bias returns the linkage to the rest position.

In use, the circuit breaker 28 is normally in its active state as shown in Figure 1 and the reset button 32 is held by its bias in its free position. The linkage 38 is in its rest position where is it held by the bias of the reset button 32 or another bias or other arrangement that holds it temporarily in position. With the linkage 38 in its rest position, the looking pin 44 is retracted from the neutral socket recess 18, so that a plug can be inserted into the socket 14 without obstruction of the socket recesses 16,18,20 into which the plug pins 22,24,26 need to enter -particularly the neutral pin 24. The power outlet 10 can be used normally and electrical power can be supplied to the plug.

When an over-current is detected, the circuit breaker 28 trips and disrupts the power supply, but even though the circuit breaker is in its tripped state, the reset button 32 remains in its free position, so the power outlet 10 still physically remains as shown in Figure 1.

To reset the circuit breaker 28, the plug is withdrawn from the socket 14 and an end or other suitable part of the tool 36 is inserted into the reset aperture 34 to press on the tool face 42 and slide the linkage 38 to the reset position as shown in Figure 2.

When the linkage 38 is in the reset position, the switch surface 40 presses on the reset button 32 and depresses it to its reset position, to reset the circuit breaker 28. Once the circuit breaker 28 has been reset, the tool 36 is retracted from the reset aperture 34, and the bias returns the reset button 32 to its free position and returns the linkage 38 to its rest position, so that the power outlet 10 is returned to its original condition as shown in Figure 1 and it can be used to provide electrical power.

If a user does not withdraw the plug from the socket 14 after the circuit breaker 28 has tripped, the neutral plug pin 24 will remain in the neutral socket recess 18 and will prevent the locking pin 44 from entering the neutral socket recess. Accordingly, the neutral plug pin 24 will block the linkage 38 from sliding to the reset position.

Accordingly, users are forced to unplug devices from the socket 14 before the circuit breaker 28 can be reset.

To assist users to know the status of the power outlet 10, the power outlet can preferably be provided with one or more visual communication device, which could take the form of a single light or light emitting diode (LED) that changes colour, multiple lights or LEDs that light up selectively, signs that light up selectively, a screen, or the like. Electronic circuitry inside the housing 12 is preferably configured to detect when the circuit breaker 28 is in the active state or in the tripped state and is preferably also configured to detect other parameters, such as whether electrical power is being supplied via the socket 14, whether power is supplied, etc. The electronic circuitry is configured to activate the visual communication device or devices to convey this information. In some embodiments, colour lights can be used to indicate the status of the power outlet 10, e.g. a blue light could indicate that the power outlet is operational, with power supplied and the circuit breaker 28 in the active state, a red light could indicate that the circuit breaker is in the tripped state, and no light could indicate that the power outlet is not connected to a live power supply. In other embodiments, signs, text, or the like could be illuminated to communicate the status of the outlet.

In some embodiments of the invention, the electronic circuitry is configured to activate the visual communication device or devices to display instructions to users to reset the circuit breaker 28 once it has tripped. Examples of instructions could include signs showing that the circuit breaker has tripped, instructing the user to remove the plug first, then instructing the user to insert the tool 26 into the reset aperture 34 and to confirm to the user that the power outlet 10 has bene reset.

The only visual display shown in the drawings, is an LED 48 that is not illuminated when the circuit breaker 28 is in the active state (and is not shown in Figure 1), but the LED is illuminated when the circuit breaker is in the tripped state (and is shown in Figure 2).

Referring to Figures 3 to 5, three further embodiments of power outlets according to the invention are shown, but the power outlets shown in Figures 3 to 5 have many features in common with the first embodiment of the power outlet 10 shown in Figures 1 and 2 and accordingly, the same reference numbers are used in Figures 3-5 to identify features in common with Figures 1 and 2. However, the outlets and linkages in Figures 3 to 5 are identified with suffixes to reference numbers 10 and 38. Each of the power outlets shown in Figures 3 to 5 includes a housing 12, electrical socket 14 with socket recesses 16,18,20, circuit breaker 28, reset switch 30, reset button 32 and reset aperture 34 as described above with reference to Figures 1 and 2, except that the positions and orientations of the circuit breaker, reset switch, reset button and/or reset aperture, are different from Figures 1 and 2.

Each of the embodiments shown in Figures 3 to 5 could also include any of the variations of visual displays described above, with reference to Figures 1 and 2, but only the single LED 48 is shown in Figures 3 to 5.

Referring to Figure 3, in the second embodiment of a power outlet 10.2 according to the present invention, the reset aperture 34 is defined on the right of the housing 12 and the linkage 38.2 includes a locking pin 44 that is configured to protrude into the earth socket recess 20 when the linkage 38.2 is in its reset position as shown in Figure 3 Referring to Figure 4, in the third embodiment of a power outlet 10.3 according to the present invention, the reset aperture 34 is defined at the same position on the housing 12 as in the first embodiment shown in Figures 1 and 2, but the linkage 38.3 includes two a locking pins 44 that are configured to protrude into the live socket recess 16 and neutral socket recess 18, respectively when the linkage 38.3 is in its reset position as shown in Figure 4. The linkage 38.3 is practically identical to the linkage shown in Figures 1 and 2, with an additional extension terminating in the locking pin 44 at the live socket recess 16.

Referring to Figure 5, in the fourth embodiment of a power outlet 10.4 according to the present invention, the reset aperture 34 is defined at the top of the housing 12 and the linkage 38.4 includes three locking pins 44 that are configured to protrude into the each of the socket recesses 16,18,20 when the linkage 38.4 is in its reset position as shown in Figure 5.

Referring to Figures 1 to 5, different physical configurations of linkages can be used in the present invention and the linkages can be configured with locking pins 44 (or other parts) that protrude into any one or more of the socket recesses 16,18,20. In each of the illustrated embodiments in Figures 1 to 5, the linkage is a unitary body that slides in a single direction into which it is pushed by pressure from the tool 36 on the tool face 42. However, in some embodiments, the linkage can comprise multiple components and/or the linkage or parts of it could pivot, twist, or move in other ways.

In some embodiments of the present invention, e.g. if the reset button 32 is located remotely from the reset aperture 34 and/or if there are space constraints in the power outlet, engagement of one or more of the locking pins 44 of the linkage in its associated pin aperture 46 could hold the part of the linkage in place and act as a datum or fulcrum about which the rest of the linkage is pivoted to press the reset button 32 with a lever action -which can provide a mechanical advantage.

Claims

CLAIMSAn electrical power outlet comprising: a housing defining at least one electrical socket, said socket including a plurality of socket recesses into which pins of a plug can be inserted; said housing also defining a reset aperture that is large enough to receive a tool, but too small to receive any part of the human body; electrical circuitry configured to make electrical contact with the pins of the plug, when the pins are received in the socket recesses; a trip-free over-current protection device inside the housing, said over-current protection device being configured to allow electrical power supply from the electrical circuitry to the plug when the over-current protection device is in an active state, and to change to a tripped state and disrupt said electrical power supply if the current between said electrical circuitry and said plug exceeds a predetermined limit, said over-current protection device including a reset switch that is operable between a free position and a reset position in which the reset switch resets the over-current protection device from the tripped stated to the active state; and a linkage inside the housing, said linkage defining a switch surface that is connectable to the reset switch, a tool face that is aligned with the reset aperture, and at least one protuberance adjacent at least one of the socket recesses; wherein said linkage is movable between: a reset position in which the protuberance obstructs its adjacent socket recess at least in part, and the switch surface presses the reset switch to its reset position; and a retracted position in which the protuberance is retracted from its adjacent socket recess and the switch surface is retracted to permit the reset switch to be in its free position; said power outlet including a bias that urges the linkage towards the retracted position, said linkage being configured to be urged against the bias to the reset position, when a tool is inserted into the reset aperture and exerts a load on the tool face.
An electrical power outlet according to claim 1, wherein the switch is biased to the free condition and the switch surface of the linkage is in contact with the switch so that the bias urges the switch to the free condition and urges the linkage to the retracted position.
3. An electrical power outlet according to claim 1 or claim 2, wherein cross-sectional dimensions of the reset aperture are less than 2mm.
4. An electrical power outlet according to any one of the preceding claims, wherein the over-current protection device is a thermal circuit breaker.
An electrical power outlet according to any one of the preceding claims, which includes at least one visual communication device and electronic circuitry that is configured to detect when the over-current protection device is the tripped state and to activate the visual communication device to show that the over-current protection device is in the tripped state.
6. An electrical power outlet according to claim 5, wherein the electronic circuitry is configured to activate the visual communication device to show when the over-current protection device is in the active state.
7. An electrical power outlet according to claim 5 or claim 6, in which the electronic circuitry is configured to activate the visual communication device to display instructions to a user to reset the over-current protection device.