Miniaturized automatic circuit breaker with a multi-functional t

Details Miniaturized automatic circuit breaker with a multi-functional t Miniaturized automatic circuit breaker with a multi-functional t

1996-09-23

1998-08-18

Nguyen, Matthew V.

High-voltage switches with arc preventing or extinguishing devic

Arc preventing or extinguishing devices

Housing structure

218156, H01H 3304

Patent

active

057960615

DESCRIPTION:

BRIEF SUMMARY
BACKGROUND OF THE INVENTION

1. Field of the Invention
The present invention relates to a miniaturized automatic switch (or circuit breaker) with a multifunctional terminal and a screen for protection against internal electrical arcs.
Modular miniaturized automatic circuit breakers for installation on rails with arrangements of several juxtaposed modules are known.
2. Description of the Related Prior Art
A circuit breaker of this type is constituted by a generally parallelepipedal, flattened rectangular casing of insulating material with two larger parallel faces or sides and further smaller faces corresponding, in relation to the conditions of installation, to a rear face, a front face, an upper face and a lower face.
The casing is formed by two half-shells coupled in a plane parallel to the sides and houses the various mechanical and electrical components of the circuit breaker.
The arrangement of the various components and access thereto from outside depend on their functions and the method of installation. For example, the rear face of the casing has to be dedicated to the mechanical installation of the circuit breaker on the support and has a recess for housing a rail and support on which the circuit breaker is engaged by means of sliding teeth disposed on the rear wall.
The manually operated circuit-breaker indicating members face the front and first and second terminals for clamping external electrical terminals open on the lower and upper faces, respectively.
The flat sides of the circuit breaker must have no obstructions or accesses to internal components except those necessary and provided specifically for establishing any mechanical interaction between juxtaposed modules.
Among the essential components of a circuit breaker of this type, which must be able to interrupt high-intensity currents, is the labyrinth for extinguishing (or, more correctly, breaking up) the electric arc which develops between the contacts of the circuit breaker when they open. This labyrinth is housed in an arc-extinguishing chamber.
As well as ionizing the air housed in the extinguishing chamber, the high arc temperatures cause a considerable increase in its pressure which may cause the circuit breaker to explode and, in order to prevent this, it is necessary to provide suitable vents for the ionized air.
These vents have to convey the ionized air away from components which are under tension or electrically conductive to avoid the striking of electric arcs or discharges due to the conductivity of the ionized gas.
The effectiveness and speed of the arc-extinguishing devices also depends upon the speed with which the ionized air under excess pressure is discharged from the extinguishing chamber.
In most automatic circuit breakers, this discharge takes place through a discharge duct opening in the lower or upper face of the circuit breaker and passing between one of the terminals and the rear face.
The duct is advantageously insulated from the terminal by means of ribs of the two half-shells which, although they are not hermetically sealed, form a labyrinth which is effective in preventing the flow of ionized air towards the terminal.
Automatic circuit breakers with third contact terminals with spring clips for the insertion of external blade or pin terminals have recently been introduced on the market, the third terminal opening in the rear wall of the circuit breaker and being electrically connected to one of the other two.
In this case, it is not possible to form the discharge duct between one of the two terminals and the rear wall owing to the presence of the third terminal and the respective electrical connection with one of the two terminals. This necessitates the provision of much less effective discharge openings at other points in the casing.
A further disadvantage of circuit breakers of this type with three terminals is constituted by the greater structural complexity, by the larger number of components to be assembled and interconnected and by the inevitable localized contact resistances which are formed during t

REFERENCES:
patent: 3683140 (1972-08-01), Peck
patent: 3891298 (1975-06-01), Yorgin et al.
patent: 4649242 (1987-03-01), Kralik
patent: 5493092 (1996-02-01), Rowe

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