AUTOMATIC SWITCH FOR LOW VOLTAGE APPLICATION

DESCRIPTION

The present invention relates to an automatic low voltage switch, and in particular to an automatic low voltage switch having a plurality of functions, while having an extremely compact structure at the same time.

Automatic low voltage switches are conventionally known electrical devices. They are normally used in electrical installations (such as residential, industrial or commercial installations) to ensure electrical installation protection, and safety for the users through the automatic opening of the switch itself, with consequential supply cut-off, when fault situations occur.

These fault situations are typically short circuits, overloads and earth leakage. In order to ensure protection against these faults, one or more protection devices able to discriminate between normal running situations and fault situations are generally associated with the actual switch itself. These devices normally comprise an actuator which, following a specific fault situation, intervenes on the kinematism of the switch to trigger the automatic release and the opening of the contacts.

The most common conventionally known protection devices are magnetothermal devices, that provide protection from short circuits and overloads, and differential devices, that provide protection from earth leakage currents.

One of the drawbacks sometimes encountered results from the fact that in certain applications the protection devices are composed of additional modules for association with the switch to create a specific protection function. Practically speaking, the switch and the protection devices are positioned inside separate cases having a predetermined modular type width (1 DIN module being equal to 17.5 mm). The cases are then associated and connected to obtain the type of protection required.

This involves an increase in cost since a plurality of cases must be supplied to house the various devices, as well as all relative connection means and interfacing to perform the operational connection with the switch, plus the relative consequential labour cost during installation.

Furthermore, even where the protection devices and the switch action part are contained within the same case, this is normally quite cumbersome in size (for example, having a width wider than two standard modules) in particular when both poles are protected. It should also be emphasised that in these cases, conventionally known protection devices require a dedicated mechanism for connection to the release kinematism, with consequential

complications during the project design stage and manufacturing of the switch and the devices associated therein.

As can be seen from the description above, conventionally known automatic switches present a series of drawbacks for which solutions have been proposed, but not in an entirely satisfactory manner.

Based on these considerations, the principle aim of the present invention is to provide an automatic low voltage switch, which is able to overcome the drawbacks described.

In the context of this task, one aim of the present invention is to provide an automatic low voltage switch that permits the creation of a plurality of protection functions, but with a reduced number of components.

Another aim of the present invention is to provide an automatic low voltage switch wherein the various components of the switch, as well as the protection devices, are all contained in a single case.

Yet another aim of the present invention is to provide an automatic low voltage switch, in particular a bi-polar switch, wherein both poles are protected and wherein the various components of the switch, as well as the protection devices, are contained within a single case.

A further aim of the present invention is to provide an automatic low voltage switch wherein the connection between the protection devices and the release kinematism of the switch is simplified.

Another aim of the present invention is to provide an automatic low voltage switch wherein the size, in terms of width, is as narrow as possible.

A further aim of the present invention is to provide an automatic low voltage switch presenting a reduced number of parts, and which is easy to assemble and to install.

Yet another aim of the present invention is to provide an automatic low voltage switch which is extremely reliable, relatively easy to manufacture and at competitive cost.

This task, as well as this and other aims which will be explained more clearly further on, are achieved with an automatic low voltage switch which comprises a case in an insulating material which contains:

- a first pole comprising a first contact and a second contact able to be connected and disconnected reciprocally;

- a second pole comprising a third contact and a fourth contact able to be connected and disconnected reciprocally;

- an open/close kinematism operationally connected to said first and second pole to perform

the connecting/disconnecting action between said first and second contacts and between said third and fourth contacts;

- a first, a second, and a third protection device conceived to activate the release of the said kinematism and the opening of said contacts following a corresponding first, second or third fault situation in an electrical installation associated with said switch;

- connecting means that operationally connect said open/close kinematism to said first, second and third protection device.

Thanks to its structure and functionality, the switch according to the invention is able to considerably simplify the production of the mechanisms and connections between the various switch components. In other words, unlike other conventionally known switches, through a single mechanism, the connecting means are able to connect the protection devices with the release kinematism of the switch, reducing the number of the mechanical components and optimising the space occupied inside the case.

Further characteristics and advantages of the invention will be made clearer from the description of preferred but not exclusive embodiments of a device according to the invention, illustrated by way of example in the appended drawings, wherein:

- Fig. 1 is a perspective view of a first embodiment of an automatic switch according to the invention;

- Fig. 2 is a side view of the switch in Fig. 1;

- Fig. 3 is a schematic functional layout of the switch in Fig. 1;

- Fig. 4 is a first side view of certain details of the switch in Fig. 1;

- Fig. 5 is a second side view of certain details of the switch in Fig. 1;

- Figs. 6, 7 and 8 are detailed views that show a first operating sequence of an automatic switch according to the invention;

- Figs. 9 and 10 are detailed views that show a second operating sequence of an automatic switch according to the invention;

- Fig. 11 is a view in perspective of a second embodiment of an automatic switch according to the invention;

- Fig. 12 is a schematic functional layout of the switch in Fig. 11;

- Fig. 13 is a perspective view of certain details of the switch in Fig. 11.

With reference to the appended Figures, an automatic low voltage switch 1 according to the invention, in its more general embodiment relating to a bi-polar switch, comprises a case 10 in insulating material, which contains a first pole 20 and a second pole 30. The rear part 11 of the case 10 is appropriately shaped and presents a means for attachment to a DIN

guide. The case 10 is conceived to consent cabling through the insertion of appropriate wiring or bars into specific terminals. Furthermore, the front part of the case 10 is conceived to be connected with a cover, not illustrated in the Figure, for the complete closure of the switch in question.

The first pole 20 comprises a first contact and a second contact 21 and 22 that can be reciprocally connected/disconnected with one other, while the second pole 30 comprises a third and a fourth contact 31 and 32 (not shown in the Figures) that can be reciprocally connected/disconnected with one other. The contacts 22 and 32 are in a fixed position whereas contacts 21 and 31 are mobile, operating between an open position, wherein they are not connected with the corresponding fixed contacts, and a closed position, wherein they are connected with said fixed contacts.

The switch also comprises an open/close kinematism 40 that is operationally connected with said first and second poles 20, 30 to perform the connecting /disconnecting action with said first and second contacts 21, 22 and with said third and fourth contacts 31, 32. Practically speaking, the open/close kinematism 40 comprises levers which transmit the movement of the knob 42 controlled by the user, to the contacts, in order to perform the opening and closing manoeuvre of the switch; moreover, said levers provoke the opening of the contacts in the case of an electrical installation fault situation associated with the switch 1. For this aim, the open/close kinematism 40 preferably comprises a means to maintain the mobile contact in closed position, and a means to release the kinematism permitting the automatic opening of the switch 1. According to one embodiment, the open/close kinematism 40 comprises at least one pair of levers, for example, the catch lever 43 and the release lever 41, which, when engaged with one other, maintain the contacts in closed position. In the case of fault, the release lever 41 is disengaged from the catch lever 43 by rotating around the centre 418, releasing the kinematism to permit an automatic opening operation by means of a mechanism that will be described in more detail further on.

The switch according to the invention is conceived to ensure the protection of electrical installations (such as residential, industrial or commercial installations) as well as the user safety by means of the automatic opening of the switch in question, with the consequential cut-off of power supply, following a first, second, or third fault situation. Typically, these fault situations refer to short circuits, overloads and earth leakage.

For this aim, the automatic switch 1 according to the invention comprises a first 50, a second 60 and a third 70 protection device conceived to activate the release of said open/close kinematism 40 and the opening of the said contacts 21,22 and 31,32 following a

corresponding first, second, or third electrical installation fault situation associated with switch 1.

The protection devices are conventionally known. The first 50 and the second 60 protection devices are normally united together and form a magnetothermal device, comprising a magnetic actuator (generally comprising a coil, a mobile core, a fixed core, a vane, or more generally a pin and a spring) that provides protection against short circuits, and a thermal actuator (generally composed of a bi-metallic strip) to provide protection against overcurrents. The third protection device 70 is normally a differential actuator that provides protection against earth leakage currents, and is generally composed of a relay and a toroidal core. The differential protection detects earth leakage current, as an imbalance between the currents of the two phases, or between phase and neutral, according to the situation.

The automatic switch 1 according to the invention also comprises connecting means 80 which operationally connect the open/close kinematism 40 to said first 50, second 60 and third 70 protection devices. Basically speaking, unlike conventionally known switches, in the switch according to the invention, the mechanical impulses of the protection devices 50, 60 and 70 are transferred to the release kinematism through a single mechanism, simplifying the structure of the switch considerably, in comparison to conventional solutions that require dedicated mechanical action for each protection device.

A first embodiment of the automatic switch 1 according to the invention, shown in Figures from 1 to 5, provides that only one of the poles is protected, thus creating the typical configuration of the so-called 1P+N switches. Practically speaking, according to this embodiment, the first 50 and second protection devices 60 are operationally associated with the first pole 20, creating magnetothermal protection (against short circuits and overcurrents) for the pole, while the third device 70 provides the differential protection of the switch.

A second embodiment of the automatic switch 1 according to the invention, shown in Figures from 11 to 13, provides the protection of both poles, thus creating the configuration of a switch with two protected poles in two modules. (2P2M).

Practically speaking, according to this embodiment, the first 50 and second 60 protection devices are operationally associated with the first pole 20, to create the magnetothermal protection for the pole; the switch also comprises a fourth 55 and fifth protection device 65 operationally associated with the second pole 30, wherein the fourth protection device 55 provides short circuit protection, and the fifth protection device 65 provides overcurrent protection for the second pole 30. In this case as well, the third device 70 provides the differential protection of the switch 1.

Figs. 6-10 show certain embodiments illustrating the automatic opening operation in a switch according to the invention.

As stated previously, an embodiment of the open/close kinematism 40 advantageously comprises a first release lever 41, conceived to release the said open/close kinematism 40 by disengaging a third connecting lever 43, to permit the automatic opening of said contacts 21,22 and 31,32. The connecting means 80 comprise, for example, a first release shaft 81, that operationally connects said open/close kinematism 40 to said first and second protection devices 50 and 60, and when present, to said fourth 55 and fifth 65 protection devices. According to this embodiment, the connecting means 80 also comprise a second intervention lever 82 that operationally connects the open/close kinematism 40 to said third protection device 70. The first release shaft 81, and the second intervention lever 82, are operationally connected to said first release lever 41. In other words, the connecting means 80 forms the only mechanical interfacing, for example by means of the first release shaft 81, and the second intervention lever 82, through which the mechanical impulse generated by the various protection devices 50, 55, 60, 65, 70 associated with a corresponding fault situation, is transmitted to the open/close kinematism 40, by acting on the release lever 41, for example.

Figs. 6 and 9 show a situation where the switch is closed and no faults are present, and the open/close kinematism 40 is maintained blocked in the closed position through the interaction of the third connecting lever 43 with the first release lever 41. In particular, according to this embodiment, one end of the lever 43 is engaged by an appropriate projection in the body of the lever 41 and as a consequence, this prevents the rotation of the lever 43 in an anti-clockwise direction (and the resulting release of the switch).

An automatic opening operation in the case of a fault caused by a short circuit is shown in Figures 6 and 7. The first protection device 50 (and the fourth protection device 55, when present) comprises a vane 501 attached to the mobile core. In normal conditions (see Figure 6) a portion of the vane 501 is positioned in proximity to a first extension 810 of the first release shaft 81.

In the case of a short circuit fault, the protection device 50 intervenes, pulling the mobile core towards the interior, and as a result, moving the attached vane 501 (see Figure 7 which shows the vane 501 movement in the right hand direction). Because of this change in position, the vane 501 operates on the first extension 810 of the shaft 81, which rotates in a clockwise direction around its own pivoting point 815. The shaft 81 presents a second extension 811 appropriately shaped and attached to the shaft. Because of the rotation of the shaft 81, the second extension 811 interacts with the first release lever 41, provoking an anti-

clockwise rotation around its own rotation centre 418. As a result, the release lever 41 disengages from the third connecting lever 43 permitting it to move, and releasing the open/close kinematism 40 that is tripped to open position, separating the mobile contacts 21 and 31 from the corresponding fixed contacts 22 and 32.

Figs. 6 and 8 illustrate an automatic opening operation in the case of overcurrent faults. The protection device 60 (and the fifth protection device 65, when present) comprises a bimetallic strip conceived to bend when overcurrents occur in the circuit. In normal conditions (see Figure 6), one portion off the strip 60 is positioned in proximity to a third extension 812 of the first release shaft 81.

In the case of overload fault, the protection device 60 intervenes through the bending of the bimetallic strip (see Fig. 8 that shows the movement of the strip 60 in a downward direction). Because of this movement the strip 60 operates on the extension 812 of the shaft 81, which rotates in a clockwise direction around its own pivot point 815. As a result of this rotation, the second extension 811 of the shaft 81 interacts with the first release lever 41 , provoking the rotation and automatic opening of the contacts as described previously.

The magnetothermal protection has been described with reference to a single pole. Obviously, in cases wherein both poles are protected the construction is basically symmetrical presenting so as to correspond with the two poles 20 and 30 respectively, the protection devices 50, 60 and 55, 65, which can operate independently on the connecting means 80 (and therefore on the shaft 81) to provoke the automatic opening of the switch 1.

Figs. 9 and 10 show the automatic opening operation in the case of an earth leakage fault. The third protection device 70 comprises a piston 701 conceived to slide as a result of earth leakage current, and therefore a current imbalance between the conductors associated with the poles. In normal conditions, (see Figure 9), one end of the piston 701 is positioned in proximity to an arm 822 of a second intervention lever 82. The intervention lever 82 is appropriately positioned to pivot at point 820, being able to rotate on this point, and being maintained in rest position by appropriate springs. The second intervention lever 82 also presents a means 821 to connect with the first release lever 41. In the case shown in the appended Figures, the intervention means is composed of a projection 821 conceived to interact with a portion 410 of the release lever 41.

In the case of an earth leakage fault, the protection device 70 intervenes provoking the movement of the piston 701 towards the exterior of the relay (see Fig. 10 showing the piston 701 movement in a right hand direction). Because of this movement, the piston 701 operates on the arm 822 of the lever 82, which rotates in an anti-clockwise direction around its own

pivot point 820. As a result of this rotation, the projection 821 on the intervention lever 82 interacts with the portion 410 of the first release lever 41, provoking the rotation in an anticlockwise direction and the automatic opening of the contacts, as described previously.

In addition to the considerable simplifications from a mechanical viewpoint, the switch according to the invention can be produced in an extremely compact manner by positioning the various components inside the case 10 in an advantageous manner.

For example, Figures 3 and 12 show that the first pole 20 and the second pole 30 are advantageously arranged in a symmetrical manner to the left and right of the longitudinal axis 100 of the switch 1, when viewed from the front. The open/close kinematism 40 can therefore be advantageously positioned in the centre in relation to said first and second poles 20, 30.

In the case wherein only a single pole is protected, Figure 3 shows that said first and second protection devices 50 and 60 are laid over the first pole 20 for example, and placed adjacent to said open/close kinematism 40. More specifically, the devices 50 and 60 for magnetothermal protection are normally grouped in a single unit (and for this reason they are illustrated as a single functional block in Figure 3) and positioned close to the pole, in a forward position when viewed from the front of the switch 1. The devices 50 and 60 are therefore operationally associated with pole 20 to create protection against short circuits and overcurrents, and operationally connected with the open/close kinematism 40 to activate the automatic release action.

In this configuration, the third protection device 70, which normally provides protection against leakage currents, is placed in a transversal position in relation to said longitudinal axis 100 and adjacent to said open/close kinematism 40. In other words, when viewed from the front of the switch, the third protection device 70 is placed in a lower position in relation to the first and second protection devices 50 and 60 and in relation to the open/close kinematism 40.

In a similar manner to the previous case, in cases wherein both poles are protected, the first and second protection devices 50 and 60 are laid over said first pole 20 and adjacent to said open/close kinematism 40, while the fourth and fifth protection devices 55 and 65 are laid over the second pole 30 and adjacent to the open/close kinematism 40 on the opposite side in relation to the first and second protection devices 50 and 60. Also in this case, the said third protection device 70 is placed in a transversal position in relation to said longitudinal axis 100 and adjacent to said open/close kinematism 40, and therefore, when viewed from the front of the switch, it is in a lower position in relation to the first, second, third and fourth protection devices and also lower in relation to the open/close kinematism 40.

The resulting structure is extremely rational and compact. The arrangement of the components inside case 1 is basically symmetrical and provides optimized use of the space within the case.

Consequently, the dimensions of the switch can be maintained very compact in size; in particular the width results as equal to two standard DIN modules (35mm), with considerable advantages from the viewpoint of modularity.

According to the description provided above, it is obvious that the switch according to the invention achieves all the aims and performs the tasks as proposed. In fact, the switch according to the invention is able to provide a large number of functions with a reduced number of components and at reduced cost.

Moreover, the use of a single connecting mechanism between the protection devices and the open/close kinematism 40 is able to simplify the structure of the switch in question, while providing a complete protection range (magnetic, thermal and differential) on one or both poles at the same time.

Furthermore, unlike state of the art switches that require dedicated mechanisms for each type of protection and/or the use of additional modules, the use of a single connecting mechanism between protection devices and the open/close kinematism 40 provides considerable reductions in production costs.

It should also be noted that particularly in the case of the configuration wherein both poles are protected, it is possible to incorporate a large number of functions in a single case in the device according to the invention, with consequential savings in manufacturing and installation costs. Moreover, thanks to the extremely compact and rational arrangement of the components inside the case, the external dimensions are considerably reduced. In particular, it is possible to produce a switch with a width equal to two standard DIN modules with both poles protected, with considerable advantages in terms of modularity and installation rationality.

According to the description provided herein, further characteristics, changes or improvements are known and can be made by those averagely skilled in the state of the art. Said characteristics, changes or improvements are therefore to be considered as being and integral part of the present invention. Practically speaking, all materials employed, as well as the dimensions and all associated forms and shapes can be of any type according to requirements and state of the art.