Four-pole terminal block for low voltage electrical distribution network

Abstract

The present invention relates to a four-pole terminal block (1) for a low voltage distribution power line, and in particular to a different functional and structural organization of the terminal block (1).

Description

[0001] FOUR-POLE TERMINAL BLOCK FOR LOW VOLTAGE ELECTRICAL DISTRIBUTION NETWORK

[0002] DESCRIPTION

[0003] The present invention relates to a terminal block for a low voltage distribution line, and in particular to a structural organization of the terminal block.

[0004] To better understand the prior art on which the invention is based, reference is made to Figure 1 , in which a three-pole terminal block (3P) of a known type is shown, i.e., based on a three-phase system powered by three phases.

[0005] The three-pole terminal block (3P) comprises a switch that is responsible for interrupting only the phases of the three-phase, indicated with letters R, S and T in the Figure, not the neutral phase N.

[0006] In this terminal block, there are four distinct possibilities for attaching the electrical terminals: on the left side of the terminal block, the letters R1 , S1 , T1 and N1 indicate a first functional group or first input set of four; on the left side of the terminal block, it is possible to define a second functional group or second set of four, indicated by R2, S2, T2 and N2; symmetrically on the right side, the letters R3, S3, T3 and N3 indicate a third functional group or third set of four; on the right side there is also a fourth functional group or fourth set of four indicated by the letters R4, S4, T4 and N4.

[0007] Each functional group is connected to a consumer downstream of the terminal block.

[0008] The known terminal block 3P therefore has an electrical configuration which is symmetrical on the vertical axis, where the switch separates the right side from the left side, from an electrical point of view.

[0009] The switch does not isolate the individual functional groups, which are located on the same side, from each other, in fact, for example with reference to the left side, the first and second functional groups are connected to each other by means of a connector which allows a direct passage of energy.

[0010] Therefore, the terminals of the first functional group and of the second functional group remain connected to each other regardless of the state of the switch (the same applies in reverse to the right side of the terminal block 3P).

[0011] Instead, the switch separates the left and right parts of the terminal block: if the switch is in the closed position, the two parts are connected (electrical connection). Thereby, the switch ensures electrical continuity between the pairs of terminals.

[0012] Furthermore, in this known terminal block 3P configuration, the N group, i.e., the poles connected to the neutral phase, are not affected by the switch but are always connected to each other.

[0013] This leads to significant management issues of the low voltage LV distribution line, especially in the event of malfunctions. In particular, Figure 2 should be considered, which diagrammatically shows two known distribution lines with two main distribution points, one on the left CS1 and the other one on the right CS2, materialized by secondary medium / low voltage MV / LV cabins. The various graphic symbols represent the consumers connected to the low voltage distribution network. The two sections powered by CS1 and CS2 converge at a point called boundary C which electrically separates them. Assuming that there is a fault on the left side of the network, the consumers connected to this side are disconnected by tripping the switch of the distribution point CS1. This implies that all the consumers on the left line are depowered, even those not necessarily affected by the fault, such as, for example, those located between the fault and the boundary C.

[0014] It will be described how, by virtue of the terminal block according to the invention, it is possible to solve this technical issue, allowing, in the event of a fault on the line, to divide it into sections which function regardless of the positioning with respect to the medium / low voltage transformer cabin.

[0015] The features and advantages of the terminal block according to the present invention will become more apparent from the following description of an embodiment thereof, given by way of explanation and not of limitation, with reference to the accompanying drawings in which:

[0016] Figure 1 shows a terminal block organized according to the prior art;

[0017] Figure 2 diagrammatically shows a current fault management system in a low voltage line; Figure 3 shows a front view of a terminal block according to the invention, in a diagrammatic version;

[0018] Figures 4 and 5 show two views of the terminal block in two different configurations;

[0019] Figure 6 shows a diagram of a low voltage distribution network; and

[0020] Figure 7 shows a diagram of the network of Figure 6 in which an electrical fault is shown.

[0021] With reference, in particular, to Figures 3 to 5, the terminal block 1 according to the invention comprises three functional groups, a branch group 11 , a left access group 12 and a right access group 13.

[0022] Each functional group comprises the three poles of the three phases of the three- phase, indicated in the Figure with R1 , S1 , T1 , R2, S2, T2, R3, S3, T3 as well as the pole of the neutral phase, indicated in the Figure with N1 , N2, N3. Therefore, each functional group comprises four poles.

[0023] The poles of the left access groups 12 and right access groups 13 are connected to a four-pole electronic switch 14, therefore they may all be disconnected, including the neutral pole N2, N3.

[0024] Again, if such terminal block is installed at the boundary point between two low voltage LV lines, the left access group 12 and the right access group 13 are connected to two different sections of a low voltage electrical distribution network LW, a left-hand one LW1 and a right-hand one LW2, as will be clearer from the continuation of the description, therefore, they receive or transmit electricity in continuity with the network starting from a distribution point upstream of the terminal block (CS1 or CS2) materialized by a secondary MV / LV cabin. While the branch group 11 electrically serves a consumer U downstream of the terminal block.

[0025] Consumer means a single consumer or a group of consumers or even a branch of a low voltage electrical distribution sub-network.

[0026] According to a peculiar aspect of the invention, the branch group 11 is electrically reversibly connectable to the left access group 12 or to the right access group 13.

[0027] To this end, the terminal block comprises electric bridging elements 15 suitable for the reversible electrical connection of the branch group 11 with the left access group 12 or with the right access group 13.

[0028] The terminal block further comprises first connection means for connecting such electrical bridging elements 15 and the left access group 12 and second connection means for connecting such electrical bridging elements 15 and the right access group 13.

[0029] Each bridging element connects a pole of the branch group with the respective pole of the access group (right or left). In fact, each pole N2 or N3, R2 or R3, S2 or S3 and T2 or T3 of the right or left access group is connected with the respective pole N1 , R1 , S1 and T 1 of the branch group.

[0030] The bridging elements 15 may take different shapes; in an embodiment shown in the Figures, the bridging elements are connectors 15 made of conductive material. The connectors 15 have a linear extension.

[0031] The connectors 15 have a substantially parallelepiped shape.

[0032] As mentioned above, the connection between the bridging element and each pole is made by means of connection means. In the embodiment variant in which the bridging elements are linear connectors, the first and second connection means comprise threaded elements 16 which engage simultaneously on a respective end 15a or 15b of the connector 15 and on the respective pole to be connected N1 , R1 , S1 , T1 , N2, N3, R2, R3, S2, S3, T2, T3. The threaded elements 16 are, in a preferred embodiment, screws.

[0033] To allow the engagement of the threaded elements 16, holes 17 are made at the ends 15a, 15b of the connector 15 and on the poles, at least one of which being threaded.

[0034] In the solution shown in the Figures, the threaded hole is the one made on the pole.

[0035] Furthermore, solutions are envisaged in which the linear connectors described above are not connected to the poles with threaded elements. An alternative may be a snap-fit connection or a connection with the engagement of a conductive pin.

[0036] The described solution requires the manual intervention by an operator to modify the electrical connection of the branch group, an intervention which consists in unscrewing the threaded elements and changing the connection of the connector with the poles of the opposite access group.

[0037] Obviously, other solutions may be envisaged which allow the movement of the bridging elements and the stable connection thereof automatically, without any manual intervention.

[0038] The terminal block 1 thus organized therefore allows connecting the branch group 11 , connected to a downstream consumer, reversibly to one of the two access groups (left 12 or right 13) and therefore to select, in fact, the current input of the terminal block 1 , i.e., the distribution point CS1 or CS2 of the network (medium or high voltage transformation cabin) from which the terminal block takes current.

[0039] Such solution is particularly advantageous if it is applied in the practical case of insertion as boundary C between two adjacent low voltage lines, in particular in the case of managing a network fault. In this regard, reference should be made to Figures 6 and 7. Figure 6 shows the network in a normal operating condition. The network LW comprises a left-hand section LW1 and a right-hand section LW2, respectively connected to a left-hand distribution point CS1 and a right-hand distribution point CS2, materialized in practice by two secondary MT / BT transformation cabins. The two network sections are connected in a boundary node C which comprises a switch which, in normal conditions of use of the network, is open (it does not allow electricity to circulate between the two sections). Normal conditions of use means a condition in which the network is not affected by faults.

[0040] In such situation, a terminal block according to the invention is installed, for example, on the left-hand section. In this installation state, the functional branch group is connected to the left access group 12 as the terminal block takes input current from the left-hand distribution point CS1.

[0041] It should now be considered the possibility that a fault occurs (shown in Figure 7 by the lightning symbol) in a section of the network interposed between the left-hand distribution point CS1 and the terminal block.

[0042] In the known case described above, in a similar situation, all the consumers pertaining to the left-hand section would be interrupted, even those interposed between the terminal block and the boundary C; consumers which, in theory, would not be affected by the issues related to the fault occurred on a distal section of the network. By virtue of to the terminal block 1 according to the invention, however, in a similar situation, it is possible to modify the connection of the branch group 11 , disconnecting it from the access group pertaining to the section of the line where the fault occurred. Such object is achieved by electrically associating the branch group to the opposite access group, pertaining to the functioning section of the line. Therefore such group is re-powered by the cabin CS2 by closing the four-pole switch of the terminal block of the boundary C.

[0043] Thereby, the opposite access group becomes the input port of the terminal block which may receive current from the opposite distribution point.

[0044] In the example of Figures 6 and 7; the branch group 11 of the terminal block is connected to the right access group 13 pertaining to the right-hand line section LW2 to take current from the secondary MT / BT transformation cabin CS2 on the right.

[0045] Before such switching operation, the step of opening the switch 14 of the terminal block 1 is carried out, so as to interrupt the left access group (12) and in particular the neutral (N2) of such group.

[0046] Once the input switch to terminal block 1 has been completed, the boundary C is closed, i.e., the switch pertaining to the boundary C is closed, to allow the passage of current from the right-hand distribution point CS2 to terminal block 1 .

[0047] The terminal block 1 therefore takes on the role of a temporary substitute boundary node, dividing the network into isolated and fault-isolatable sections.

[0048] By reorganizing the electrical network in this manner, the consumers interposed between the terminal block 1 and the boundary C may be activated (or reactivated) and therefore not suffer the effects of the electrical fault. Only the consumers comprised between the terminal block 1 and the left-hand distribution point CS1 (indicated in Figure 7 by the dotted line) will be disconnected and shall wait for the fault to be resolved to be restored.

[0049] It goes without saying that this solution has several advantages.

[0050] By virtue of the fact that the neutral poles are connected to the switch 14 of the terminal block, it is possible to manage the power switch from one access group to another and, above all, the connection by means of a boundary node.

[0051] The change in the organization of the terminal block and therefore of the access group to which the downstream consumer pertains may be obtained quickly, without having to operate on all the poles of the terminal block as in the conventional case.

[0052] The operator may therefore intervene in a targeted and rapid manner, quickly restoring the consumers located between the terminal block and the boundary in the event of a network fault.

[0053] Therefore, the terminal block according to the invention, in this case, behaves as a new boundary node, dividing the distribution network into sections which may be isolated from each other in the event of a fault or another operational need.

[0054] The present invention has been described up to now with reference to the preferred embodiments thereof. It is to be understood that other embodiments may exist which pertain to the same inventive core, all falling within the scope of protection of the claims reported below.

Claims

CLAIMS1 . An electrical terminal block (1) intended for installation in a low voltage electrical distribution network, said terminal block comprising three functional groups, a branch group (11 ) connected to an electrical consumer downstream of said terminal block, a left access group (12) and a right access group (13) wherein said access groups are connected to respective electricity distribution points located upstream of the terminal block, wherein each functional group (11 , 12, 13) comprises four poles of which the three poles of the three phases of the three-phase (R1 , S1 , T1 , R2, S2, T2, R3, S3, T3) and the pole of the neutral phase (N1 , N2, N3), said terminal block being characterized in that it comprises electric bridging elements (15) suitable for the reversible electrical connection of the branch group (11) with the left access group (12) or with the right access group (13).

2. A terminal block (1 ) according to claim 1 , wherein the left access group (12) and right access group (13), i.e., the respective poles (N2, N3) thereof, are connected to a switch (14) of said terminal block.

3. A terminal block (1 ) according to claim 1 or 2, further comprising first connection means for connecting such electric bridging elements (15) and the left access group (12) and second connection means for connecting such electric bridging elements (15) and the right access group (13).

4. A terminal block (1 ) according to claim 3, wherein said bridging elements are connectors (15), made in a conductive material, having a linear extension.

5. A terminal block (1 ) according to claim 4, wherein the connectors (15) have a substantially parallelepiped shape.

6. A terminal block (1 ) according to claim 4 or 5, wherein said first and second connection means comprise threaded elements (16) which engage simultaneously on a respective end (15a, 15b) of said connector (15) and on the respective pole of the respective access group to be connected (N1 , R1 , S1 , T1 , N2, N3, R2, R3, S2, S3, T2, T3).

7. A terminal block (1 ) according to claim 6, wherein on said poles and on the ends (15a, 15b) of said connector (15) holes (17) are obtained, at least one of which is threaded to allow the engagement of said threaded elements (16).

8. A low voltage electrical distribution network with a terminal block (1) according to any one of the preceding claims.

9. A low-voltage electrical distribution network according to claim 8, comprising at least one left-hand section (LW1) and a right-hand section (LW2), respectively defined between a left-hand electricity distribution point (CS1) or a right-hand electricity distribution point (CS2) and a boundary node (C) comprising a switch electrically separating said two sections under normal conditions of use of said network, to each of said left-hand and right-hand sections electrically connecting at least one consumer (U), said terminal block (1) being installed in one of said left-hand or right-hand sections.

10. A method for managing faults in the low voltage electrical distribution network according to the claims 8 or 9, comprising the steps of:- detecting a fault in one of said left-hand or right-hand sections;- actuating the switch (14) of said terminal block (1) to exclude the poles (N2, R2, S2, T2, N3, R3, S3, T3) of the access group (12, 13) pertaining to the section where said fault occurred; modifying the electrical connection of said terminal block by electrically connecting said branch group (11) to the access group (13, 12) opposite to the one in which said failure occurred;- actuating the switch of said boundary node (C) to establish the electrical connection between said left-hand section and said right-hand section so that said terminal block (1) receives, by means of said opposite access group, electricity from the distribution point (CS1 , CS2) opposite with respect to the one whose section of the network the fault occurred.

Images