GB2411523A

GB2411523A - Circuit interrupter

Info

Publication number: GB2411523A
Application number: GB0404029A
Authority: GB
Inventors: Kai Chi Chan
Original assignee: WELLONG TRADING Ltd
Current assignee: WELLONG TRADING Ltd
Priority date: 2004-02-24
Filing date: 2004-02-24
Publication date: 2005-08-31
Anticipated expiration: 2024-02-24
Also published as: CN1661750A; GB2411523B; GB0404029D0

Abstract

A circuit interrupter comprises a frame 17, a first carriage 20 movably biased with respect to the frame, first electrical contacts 18 located upon the first carriage, a second carriage 21 movably biased with respect to the frame, and second electrical contacts 19 located upon the second carriage and opposing the first electrical contact. A locking device 15 maintains a positional relationship between the first and second carriages when locked in which the first and second electrical contacts are mutually engaged. Also included is an event-activated release mechanism for unlocking the locking device.

Description

241 1 523

GROUND FAULT CIRCUIT INTERRUPTER

BACKGROUND OF THE INVENTION

The present invention relates to circuit interrupters.

More particularly, although not exclusively, the invention relates to a circuit interrupter having first and second movable electrical contacts.

Circuit interrupters are known to comprise a fixed electrical contact and a movable electrical contact. The electrical contacts remain engaged until a solenoid is tipped to move the movable electrical contact away from the fixed electrical contact to thereby break or open a circuit. The solenoid might be tripped by an earth leakage detector or an alternating current overload detector for example.

Known circuit interrupters can be complex in design and therefore expensive to manufacture and might suffer from unreliability.

OBJECTS OF THE INVENTION

It is an object of the present invention to overcome or substantially ameliorate the above disadvantages and/or more generally to provide an improved circuit interrupter.

DISCLOSURE OF THE INVENTION

There is disclosed herein a circuit interrupter comprising a frame, a first carriage movably biased with respect to the frame, a first electrical contact located upon the first carriage, a second carriage movably biased with respect to the frame, and a second electrical contact located upon the second carriage and opposing the first electrical contact. A locking device maintains a positional relationship between the first and second carriages when locked in which the first and second electrical contacts are mutually engaged. Also included is an eventactivated release mechanism for unlocking the locking device.

Preferably, the locking device comprises a latch that engages and retains the first carriage.

Preferably, the latch is mounted pivotally to the frame.

Preferably, the locking device further comprises a solenoid which when activated attracts the latch to maintain it in a locked position.

Preferably, the latch comprises a recess and the first carriage comprises a tongue extending into the recess when the latch is in the locked position.

The circuit interrupter may further comprise a first spring extending between the frame and the first carriage and wherein the second carriage has extending from it a reset button - depression of which causes the second carriage to move against the first carriage which in turn moves against the first spring.

Preferably, the circuit interrupter further comprises a second spring extending between the frame and the second carriage, the second spring serving to maintain a separation between the first and second carriages upon release of the reset button.

Preferably' the circuit interrupter further comprises a solenoid-assist spring extending between the frame and the latch.

The frame is preferably attached internally of or formed integrally within a plug body having electrical contact pins extending therefrom and by which the plug body can be attached to an electrical outlet socket.

The reset button preferably extends through an aperture in the plug body.

BRIEF DESCRIPTION OF DRAWINGS

A preferred form of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 is a schematic cross-sectional elevation of a plug body having a circuit interrupter embodying the invention built into it; Figure 2 is a schematic elevation of the plug body of Figure 1; Figure 3 is a schematic cross-sectional side elevation of the circuit interrupter in a circuitopen state; Figure 4 is a schematic cross-sectional end elevation of the circuit interrupter of Figure 3 in a circuit-open state; Figure 5 is a schematic elevational view of the circuit interrupter of Figure 3; Figures 6A and 6B are schematic elevational and cross- sectional views respectively of the circuit interrupter in a tripped or open state; Figures 7A and 7B are schematic elevational and cross- sectional views respectively of the circuit interrupter - s - in a circuit-closed state with the reset button depressed; and Figures 8A and 8B are schematic elevational and cross- sectional views respectively of the circuit interrupter in a circuit- closed state with the reset button released.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT

In the accompanying drawings, there is depicted schematically a circuit interrupter 12 mounted within a moulded plastics plug body 10. Electrical pins 11 extend from the plug body for insertion into the apertures of a wall outlet or extension cord socket for example.

There is a reset button 13 having a spring-loaded push cap 13a projecting through the plug body casing for manual depression when required.

The circuit interrupter 12 comprises a frame 17 that is snap-engaged or otherwise secured internally to the plug body 10. The frame 17 would typically be formed as a plastics moulding or a moulding of other dielectric material.

A first carriage 20 is movably mounted to the frame 17 and biased away from the frame by a first coil spring 23.

The first carriage 20 has mounted on it a pair of first electrical contacts 18. These electrical contacts are connected to electrical tracks on the first carriage via which alternating current passes from the pins 11. One of the electrical contacts 18 would be associated with the live (or hot) circuit whereas the other would be associated with the neutral circuit.

The reset button 13 is formed integrally with a second carriage 21 that is movably mounted to the frame 17 and biased away from the frame by a second coil spring 22.

The portion of the first carriage 20 against which the first spring 23 bears is constrained underneath the second carriage 21 so that when the reset button 13 is depressed and the second carriage 21 moves down, the first carriage must also moved down. However, the second carriage 21, after depression of the reset button 13, can lift away from the first carriage 20 under the action of the second coil spring 22. In this case, the first carriage 20 is locked down by a locking device associated with a solenoid 14 to be described below.

The second carriage 21 has mounted on it a pair of second electrical contacts 19. One of these would be associated with the live (or hot) electrical circuit, whereas the other would-be associated with the neutral circuit. These electrical contacts are opposed to the first electrical contacts 18 and are connected to electrical tracks on the second carriage. When the first electrical contacts 18 and second electrical contacts 19 are mutually engaged, electrical alternating current from the pins 11 is allowed to pass via the engaging electrical contacts en route to a power cord (not shown) that extends from the plug body to an appliance for example.

The solenoid 14 is mounted to the frame 17 and when energised attracts a ferrous plate 24 magnetically. The ferrous plate 24 is mounted upon a plate carrier 15 that is spring-biased by an assist spring 16 away from the frame 17.

The mechanism by which the first carriage 20 is locked down comprises a tongue 26 that is attached to or formed integrally with the first carriage. This tongue cooperates with a latch 25 that is attached to the plate carrier 15. As shown in Figure 7B, the latch 25 is mounted to the frame 17 by a screw or pin 28 that also passes through the plate carrier 15 to serve as a pivot for both the plate and latch.

The latch 25 includes a recess 27 having a curved periphery that rides smoothly upon the curved profile of the tongue 26. The assist spring 16 biases the latch 25 against the tongue 26, albeit with insufficient force to maintain the recess 27 closed over the tongue 26 against the force of the spring 23. It is only when the solenoid 14 is energised to attract the ferrous plate that the latch 25 maintains the locked position of the tongue 26 to maintain electrical contact between the electrical contacts 18 and 19.

The solenoid would be deactivated by a ground fault (earth leakage) detection circuit or a current overload detection circuit (not shown).

In normal use as depicted in Figure 8B, alternating current is allowed to pass across the engaged electrical contacts 18 and 19. If an overload situation or earth leakage situation is detected, the solenoid 14 will deactivate as shown in Figure 6B. At this moment, the force of spring 23 transmitted through tongue 26 via the latch 25 will overcome the force of assist spring 16 so that the latch 25 will move into the position depicted.

Resetting the circuit interrupter is achieved by depressing the reset button 13. As shown in Figure 7B, separation between the electrical contacts 18 and 19 is maintained as both the first and second carriages move down. After releasing the reset button 13 is shown in Figure 8B, the second carriage 21 and its electrical contacts 19 move upwardly to engage the electrical contacts 18 in a position that is maintained thereafter by interaction of the latch 25 with tongue 26 as described above.

It should be appreciated that modifications and - 9 - alterations obvious to those skilled in the art are not to be considered as beyond the scope of the present invention. For example, the circuit interrupter need not be formed into a plug body, but could be used in meter boxes, transformers and electrical appliances for

example.

Claims

1. A circuit interrupter comprising: a frame, a first carriage movably biased with respect to the frame, a first electrical contact located upon the first carriage, a second carriage movably biased with respect to the frame, a second electrical contact located upon the second carriage and opposing the first electrical contact, a locking device maintaining a positional relationship between the first and second carriages when locked in which the first and second electrical contacts are mutually engaged, and an event-activated release mechanism for unlocking the locking device.

2. The circuit interrupter of Claim 1, wherein the locking device comprises a latch that engages and retains the first carriage.

3. The circuit interrupter of Claim 2, wherein the latch is mounted pivotally to the frame.

4. The circuit interrupter of Claim 2, wherein the locking device further comprises a solenoid which when - 11 activated attracts the latch to maintain it in a locked position.

5. The circuit interrupter of Claim 4, wherein the latch comprises a recess and the first carriage comprises a tongue extending into the recess when the latch is in the locked position.

6. The circuit interrupter of any one of Claims 1 to 5, further comprising a first spring extending between the frame and the first carriage and wherein the second carriage has extending from it a reset button depression of which causes the second carriage to move against the first carriage which in turn moves against the first spring.

7. The circuit interrupter of Claim 6, further comprising a second spring extending between the frame and the second carriage, the second spring serving to maintain a separation between the first and second carriages upon release of the reset button.

8. The circuit interrupter of any one of Claims 2 to 7, further comprising a solenoid-assist spring extending between the frame and the latch.

9. The circuit interrupter of any one of Claims 1 to 8, wherein the frame is attached internally of, or formed integrally within a plug body having electrical contact pins extending therefrom and by which the plug body can be attached to an electrical outlet socket.

10. The circuit interrupter of Claim 9, wherein the reset button extends through an aperture in the plug body.

11. A circuit interrupter substantially as hereinbefore described with reference to the accompanying drawings.