Multi-polar low tension circuit breaker includes insulating disc carrying conductive lamella between contacts, breaking contact by sliding

Holder (s):

© Agent (s): COMBIER MICHEL.

© MULTIPOLAR CIRCUIT BREAKER WITH VERY LOW ENERGY CONSUMPTION FOR LOW VOLTAGE PROTECTION AND SECURITY APPLICATIONS AND HIGH CURRENTS.

FR 2 801 418 - A1 (JJ Very low power consumption multipole circuit breaker, intended for low voltage and high current protection and safety applications.

The invention relates to a device for opening and closing an electrical circuit obtained by rotation of a thin insulating disc (5) provided with conductive blades (6) between two pads (4) serving as electrodes for supplying current.

The pads (4) are articulated along 3 axes by means of a ball (2) embedded in a spherical imprint formed in said pads. The assembly is kept under pressure by two elastic blades (1).

The device according to the invention is particularly suitable for the protection of systems using batteries and installed on cars, trucks, caravans and boats.

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- The present invention relates to the production of an electrical contactor or circuit breaker for low voltages and very high currents, intended more particularly for the protection of batteries and associated electrical equipment.

The materials existing on the market, such as relay contactors or remote control switches, do not respond well to the need for systems operating on low-voltage batteries because these, when they are capable of cutting high currents, are generally sized to operate at medium voltage and are therefore heavy, bulky and expensive. In addition, they consume a lot of power in the closed state, which is incompatible with the need for equipment operating on battery. Certain products, intended for cars, trucks and boats are strictly manual in use and are therefore unsuitable for being automated in order to guarantee electrical safety functions while ensuring sufficient ease of use.

The object of the invention is the use of two combined effects to limit the destructive action of the electric arc. The first is the potentiometric effect or progressive resistance variation created in the vicinity of the electrical contact at the time of opening, thus rapidly reducing the breaking current, the second consisting in transferring the electric arc to areas of the electrodes not involved in conduction in the closed state.

These two effects are obtained by the use of sliding contacts or pads, of moderately conductive, soft and refractory material.

The opening and closing of the contact is ensured by the displacement of a sliding blade partly conductive and partly insulating between two conductive pads. The conductive part of the sliding blade is made of the same material as the pads, the insulating part of hard and refractory material.

A variant of the device consists in inserting, at

- 2 inside the conductive strip and the pads, a malleable and weakly resistive alloy core. This core, always kept away from the electric arc thanks to the large size of the pads, does not have to be made of refractory material which simplifies its design.

The invention therefore makes it possible to neutralize the destructive effect of the electric arc due to the breaking of strong currents, on the one hand by progressively reducing the current by the insertion of a variable resistance induced by the sliding of the contacts and d 'other hand by rejecting the electric arc on a part of the contacts very refractory and having little or no effect on conduction in the closed state.

The accompanying drawings illustrate the invention:

Figure 1 shows, in section, the principle of the device and its configuration in the closed and open state.

With reference to the drawing in FIG. 1, the basic device comprises an insulating sliding blade (5) pierced with a hole receiving the conductive blade (6), which is provided in its center with a weakly resistive cylindrical core (7) .

This blade is clamped between two conductive pads (4), also provided with a weakly resistive core (3), and provided with a concave spherical imprint.

The two pads are kept in contact with the sliding blade by two flexible blades (1) provided with a ball (2). This ball makes it possible, through the spherical imprint of the pads, to ensure free articulation and rotation of said pads. This arrangement or any other equivalent arrangement makes it possible to ensure contact over the entire flat face of the pads whatever the degree of wear or the alignment errors of the device.

Furthermore, the freedom in rotation of the pads makes it possible to distribute the wear due to the effect of the arc on their entire periphery and thus considerably increase their longevity.

The flexible blades allow, in addition to their support spring function, to ensure the conduction of electric current.

- 3 Initially, in the “closed circuit” state, the conductive strip (6) is in the central position, in the axis of the pads (4). The current is established through the conductive cores (3) and (7). The electrical resistance is very low.

The longitudinal movement of the sliding blade causes a gradual increase in electrical resistance, which has the effect of rapidly reducing the current.

At the end of its movement, the conductive strip (6) breaks the electrical circuit between its outer edge and the peripheral part of the pads (4).

The electric arc, already weakened by the resistance of the contact which has become high, then gushes between pads and conductive blade, therefore between refractory materials, not very sensitive to very high temperatures and whose alteration has no effect on the quality electrical contact.

In the "open circuit" position, the pads (4) are kept separate by the insulating sliding blade (5).

Figure 2 shows, in partial section and top view, an application of the device for the production of a bipolar circuit breaker.

Referring to the drawing of Figure 2, the sliding blade consists of a disc (5) supporting two resistive blades (6) each equipped with a good conductive core (7).

This disc is integral with the shaft (12) allowing it to be rotated either by the motor (8) or by the lever (9).

The disc (5) is clamped between two pairs of resistive pads (4) equipped with a good conductive core (3).

These pads are kept under pressure on the disc (5) by the balls (2) secured to the elastic blades (1).

These elastic blades (1) are held in position by the bolts (10), which are connected to the current inlets (11).

Contacts are opened and closed

- 4 by successive 90 ° rotations of the disc (5).

According to particular embodiments:

- the conductive part of the sliding blade and the pads can be made of graphite or any carbon-based grade.

- the insulating part of the blade can be made of ceramic.

- The central core of the conductive strip and the pads can be made of silver or a silver alloy.

By way of nonlimiting example, the pads and the conductive blade will have a diameter of 20 mm, the cores a diameter of 4 mm, the support disk of the conductive blades a diameter of 64 mm. The entire device will be able to fit in a volume of 100 × 80 × 80 mm and tolerate cut-off currents greater than 1000 amperes without significant fatigue.

The device according to the invention is particularly intended to replace the manual circuit breakers traditionally used in applications using low voltage batteries for professional or domestic uses applied to caravans and pleasure boats. It offers the possibility of remote control and automation providing security, ease and operational safety. The total absence of electrical consumption outside the switching phases makes it particularly suitable for applications where energy saving is a dimensioning factor.