OA10971A - Protection device for low voltage distribution networks - Google Patents

Abstract

The insertable module has a commandable switch section with a normalised fusible cartridge.

Description

1 010971

DEVICE FOR PROTECTING LOW VOLTAGE DEDISTRIBUTION NETWORKS

The present invention relates to a device for the protection of low-voltage, over-current and overload distribution networks comprising an insulating base provided with at least a first and a second jaw respectively for receiving a first and a second contact terminal of a module intended for cut off the electrical current flowing in the line in case of overcurrent and overload, said device being further provided with a gripping handle for extracting said module of the insulating base.

Low-voltage electrical distribution systems are generally protected against current by fuses, which are devices whose reliability and durability is no longer to be demonstrated. Refurbished after each operation, they are almost not sensitive to aging due to temperature stress related to the normal operation of the network.

While being considered as protection elements of very good reliability, they nevertheless have limits of operation, related to their nature. Theyprovide very good protection against shortcircuits (strong and fast overcurrent) but do notprovide overload protection (low value, but prolonged overcurrent).

A short circuit is due to an insulation fault between two conductors of different polarities. The amount obtained in the defect will be all the more important as the impedance against the point of default and the energy source is low. 2 010971

In relatively recent distribution networks, the cables are fairly widely dimensioned and of low length, so that a fault at the end of the cable is seen from the source as a short circuit. In this configuration, the protection fuses fulfill their role correctly, and are melting in a sufficiently short time, so as not to damage the equipment upstream by overheating.

A certain number of BTancian distribution networks, particularly in rural areas, are built on bare conductors, of small section, and over very long distances.

In these cases, the fuse protection becomes insufficient because the characteristics of the lines cause an insulation fault at the end of the line causes a low overcurrent at the source and protections that is insufficient to trigger the fuse fuse.

The object of the invention is to overcome the inadequacies of the known protective devices described above.

According to the invention, the module intended to cut the electrical current circulating in the line in the event of over-currents and overloads is characterized in that it comprises a controlled switch mounted on the insulating base with a standardized fuse cartridge, and in that the handle comprises loosening means for extracting the fusible cartridge independently of the controlled switch. The combination of the controlled switch and the fuse cartridge makes it possible to solve the problems of protection of the long lines by simply adapting the equipment in place to the extent that the existing standards can be reused to continue the module for breaking the current. Other characteristics and advantages of the invention will emerge from the description which follows, taken by way of non-limiting example, with reference to the appended figures in which:

Figure 1 schematically shows a fuse socket of the prior art; - Figure 2 schematically shows an elevational view of a device according to the invention; - Figure 3 schematically shows a device according to one invention, the elements are assembled; FIG. 4 represents a partial and enlarged side view of a lateral part of the device according to the invention.

FIGS. 2 and 3 schematically represent a device for protecting low-voltage and over-load electrical networks comprising an insulating base 4 provided with a first jaw 6 and a second jaw 8 respectively intended to receive a first contact terminal 10 and a second terminal contact 12 12 of a module 14, framed by broken lines onfigures 2 and 3. Said module 14 is intended to cut the electric current circulating in the line in case ofcurlens and overloads on the bassetension line. The device also comprises a dehensioning handle 16 intended to remove said module 14 wedge 4. 4 010971

As can be seen in FIGS. 2 and 3, the module 14 comprises a controlled unipolar switch 20 mounted on the insulating base 4 with a standardized fuse 22.

Said module 14 further comprises a coil 24 intended to measure the electric current flowing in the low voltage line. This coil 24 is connected to an electronic circuit (not shown) and which can be integrated with the switch 20 and which is intended to command the opening of this switch 20 when the current measured reaches a preset predetermined value.

According to a preferred embodiment of the invention for optimizing the space available on the standard base 4, the controlled switch 20 is arranged between the fuse cartridge 22 and said base isolating 4. In addition, said switch 20 comprises, a third jaw 26 and a fourth jaw 28destinées respectively to receive a first contact cutter 30 and a second contact knife 32 deladite cartridge fuse 22, shown in dashed lines on Figures 2 and 3. As can be seen in Figures 2 and 3, the first terminal 10 and the secondborne 12 of the module 14 are respectively constituted bya third contact knife and a fourth contact pad fixed on the controlled switch 20 which are respectively housed in the first jaw6 and in the second jaw 8 when the module 14 is mounted on the base 4.

The first, second, third and fourth jaws 6, 8, 26, 28 may be elastically tightened or clamped. When elastically tightened, traction on the handle 16 has the effect of extracting the entire module 14 from the base 4. In this case, in order to guarantee the independence of the extraction of the fusible cartridge 22 with respect to the extraction With the controlled switch 20, the handle is rotatably mounted relative to the base 4 about a central axis 25 and includes means for loosening the first contact knife 30 and the second contact knife 32 of the fuse 22. respectively of the third jaw 26 and the fourth jaw 28 of the controlled switch 20.

As can be seen in FIG. 4, schematically representing the mechanism making it possible to move the jaws 26 and 28 away from the switch 20, said loosening means comprise a lever 40solidary of the handle 16, and extending by a blade 42 which, by way of a rotation of said handle 16 around Tax 25, spaced apart said third and fourth jaws 26 and 28 which remain spaced during the extraction of the fuse cartridge 22.

With these loosening means, a simpletraction on the handle 16 makes it possible to extract the module 14 from the jaws 6 and 8 of the base 4 and unerotation of the handle 6 causes, after opening of the switch 20, by action on the cam 42, opening of the jaws 26 and 28 of the switch 20.This allows to extract without effort the knives 30 and 32de the fuse cartridge 22 of said jaws 26, 28after opening said switch 20.

According to the preferred embodiment of the invention, the handle 6 comprises means that, during rotation about the axis 25, open the switch 20 before extracting the fuse 22.

According to a second embodiment of the invention, the module 14 is constituted by a circuit breaker likely to be open both at the appearance of a short circuit and when an overload occurs.

Such a solution is implemented by simple adaptation of the electrical connections in the standard fuse holder 4.

Claims (9)

7 010971 CLAIMS 1. Device for protecting low voltage electrical networks against overcurrents and against overloads comprising an insulating base (4) provided with at least a first and a second jaw (6, 8) respectively for receiving a first and a second contact terminals ( 10, 12) of a module (14) for cutting the electric current flowing in the line in case of overcurrent and overloads, a gripping handle (16) for extracting the module (14) from the insulating base (4), characterized in said module (14) comprises a controlled switch (20) mounted · on said base (4), with a fusiblenormalized cartridge (22) and in that said handle (16) comprises loosening means for extracting fuse cartridge (22) of the module (14) independently of said controlled switch (20). 2. Device according to claim 1, characterized in that said controlled switch (20) is unipolar and is connected in series with the fuse cartridge (22), between said fuse cartridge (22) and insulating base (4) and that it comprises a third jaw (26) and a fourth jaw (28) for respectively receiving a first contact knife (30) and a second contact knife (32) of said fuse cartridge (22). 3. Device according to claim 1 or 2, characterized in that said releasing meanscomportent lever (40) integral with the handle (16) extending by a cam (42) which, by a rotationde said handle (16), comes spacing said third and fourth jaws (26, 28) from the controlled switch (20), the third and fourth jaws (26, 28) remaining apart during fuse linkage extraction (22). 4. Device according to claim 3, characterized in that the handle (16) furthermore comprises means for opening the switch (20) before extracting the fuse cartridge (22) of the module (14). 5. Device according to one of claims 1 to 4, characterized in that the first terminal (10) and the second terminal (12) of the module (14) are respectively constituted by a third contact knife and a fourth contact knife fixed on the controlled switch (20) and in that said third and fourth knives are respectively housed in the first jaw (6) and in the second jaw (8) when the module (14) is mounted on the base (4). 6. Device according to claim 5, characterized in that said first jaw (6), second jaw (8), can be clamped clamp orelastic, and the third jaw (26) and fourthemachine (28) are elastically clamping. 7. Device according to claim 6, characterized in that said first jaw (6), second jaw (8), can be clamped or elastic clamping and the third jaw (26) and fourth jem (28) are clamped clamping. 8. Device according to claim 4, characterized in that the gripping handle (16) is mounted mobile in rotation relative to the base (4). 9 010971 9. Device according to one of claims 1 to 8, characterized in that said module (14) further comprises a coil (24) for measuring the electric current flowing in the low voltage line, said coil being connected to an electronic circuit for tocommander the opening of said switch (20) when the current measured reaches a predetermined setpoint.