Electricity: electrothermally or thermally actuated switches – Electrothermally actuated switches – With bimetallic elements
Patent
1997-06-18
2000-12-12
Picard, Leo P.
Electricity: electrothermally or thermally actuated switches
Electrothermally actuated switches
With bimetallic elements
337 3, 337 13, 337 38, 337 45, 337 59, 200286, 335 35, 335 45, 335145, 335176, H01H 7300, H01H 7348, H01H 7512
Patent
active
061604704
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention relates to a circuit breaker. More particularly, the invention relates to a circuit breaker of the type comprising a base and a cover, the base and/or cover having a rear wall portion, a front wall portion and a pair of side wall portions extending between the front and rear wall portions to define an enclosure, upper and lower rail mounting devices extending from the rear wall of the housing, one of the rail mounting devices comprising a pair of spaced-apart jaws extending from the rear wall of the housing, a calibration access aperture extending through a wall of the housing through which access is gained to a calibration device in the enclosure.
Circuit breakers of this type are known. In conventional circuit breakers however the aperture through which access is gained to the calibration device in the enclosure is generally located in a position such that the calibration may be tampered with. In some cases the calibration aperture is covered by a separate cover, however, this is not entirely satisfactory as the cover may also be removed.
SUMMARY OF THE INVENTION
There is therefore a need for an improved circuit breaker which will overcome this difficulty.
This invention is characterised in that the calibration access aperture is located to permit access to the calibration device in the enclosure through the jaws of the rail mounting device.
The advantage of this arrangement is in locating the access to the calibration device in an inaccessible position so that the calibration cannot be easily tampered with and, more particularly, cannot be tampered with while the circuit breaker is in use. This removes the need to have a cover over the calibration device.
In one embodiment of the invention, the calibration access aperture extends through the housing between the jaws of the rail mounting device. This will generally be the most beneficial position for the calibration access aperture.
Preferably the calibration access aperture extends through a side wall portion of the housing. This arrangement facilitates access to the calibration access aperture when the circuit breaker is disconnected and dismounted from mounting rails.
To facilitate ease of operation with a simple operating device, preferably the calibration access aperture extends substantially parallel to a longitudinal axis of the rear wall of the housing.
In one embodiment of the invention, the upper rail mounting device comprises the pair of spaced-apart jaws. The particular advantage of this feature is that the upper rail mounting device is usually a line terminal for coupling to a source of electricity and the calibration cannot be tampered with without uncoupling the circuit breaker from the source of electricity.
In one arrangement, for simplicity of operation, preferably the calibration device comprises a calibration screw.
To facilitate ease of operation of the calibration screw, preferably the screw is rotatably mounted in a nut which is located in the housing.
For ease of assembly, preferably the screw is an interference fit in the circuit breaker housing.
In one embodiment of the invention, a bimetallic element is mounted in the enclosure and the calibration device comprises a calibration screw engaging the bimetallic element.
The invention will be more clearly understood from the following description thereof given by way of example only with reference to the accompanying drawings in which:--
BRIEF DESCRIPTION OF DRAWINGS
FIG. 1 is a plan view of a circuit breaker according to the invention with a cover removed;
FIG. 2 is a perspective view of a detail of the circuit breaker of FIG. 1;
FIG. 3 is a perspective view of a base part of the circuit breaker; and
FIG. 4 is a perspective view of a cover part of the circuit breaker.
DETAILED DESCRIPTION
Referring to the drawings, there is illustrated a circuit breaker 1 including a line terminal 2 for coupling to a source of electricity and a load terminal 3 for coupling to a load. The current path includes a coil 4 and an arc runner 6. An arc s
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Hurst Dermot
O'Carroll Thomas
Regan Desmond
Picard Leo P.
Vortman Anatoly
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