GB2126790A - A three phase circuit-breaker panel - Google Patents

Abstract

A three phase switchboard panel designed to cooperate with two identical or similar panels in order to form with a transformer a distribution substation comprises at least one three phase, sealed bushing (3) for connection with input cables, a tripolar earth disconnecting switch, and a set of bus bars. The panel is divided into two compartments (1, 2) which are sealed in respect of one another and each one in respect of the outside, one of the compartments (2) containing the set of bars (41, 42, 43) and the other containing the remainder of the equipment. The two compartments are separated by a partition provided with three hollow, cylindrical isolating bushings (31, 32, 33) which also serve as circuit breaker blasting cylinders and as supports for the bus bars (41, 42, 43). <IMAGE>

Description

SPECIFICATION A three phase cell The invention relates to a three phase cell, for example a distribution cell for a compact transformation station.

It relates to a three phase cell designed to cooperate with, generally, two other identical or similar cells, this cell combination being placed between two high tension cable inputs and a stepdown transformer.

Each cell comprises, for each poise, a circuit breaker and, possibly, an earth disconnecting switch; furthermore, the cell comprises an input connection and a three phase set of bars for its connection with a neighbouring cell. Finally, the cell comprises an output isolating bushing for the connection with the transformer.

Cells of this type are known, and various solutions have been suggested in order to reduce their space requirement, both on the ground and in the air.

It is indeed imperative for the distribution stations to have the smallest possible dimensions, especially due to the price of land in the urban zone where these stations are installed.

All the solutions suggested require internal isolation of the cells by means of a gas having high dielectric capacity, such as sulphuric hexafluoride (SF6).

It has thus been possible to create stations through the juxtaposition of sulphuric hexafluoride-isolated cells, the overall dimensions of which were satisfactory.

Unfortunately, it has been ascertained that any fault in one cell tended to spread to the others, and, more particularly, that an earth to phase fault, which is not very serious, could turn into a fault between phases, causing a great deal of damage in all the cells.

A cell is desirable which ensures greater reliability, while at the same time maintaining the compact overall dimensions.

According to the present invention there is provided a three phase cell adapted to cooperate with two similar three phase cells and a transformer to form a distribution station, the three phase cell being divided into two compartments which are sealed in respect of one another and in respect of the outside, one of the compartments containing a set of bars and the other compartment containing at least one three phase sealed bushing for connection with input cables, a tripolar circuit breaker with pneumatic autoblasting, and a tripolar earth disconnecting switch, the two compartments being separated by a tight partition provided with three hollow, cylindrical isolating bushings wherein the hollow cylindrical bushings serve as circuit breaker blasting cylinders and as supports for the bars.

According to an embodiment of the invention, a triphase cell designed to cooperate with, as a rule, two identical or similar cells in order to form with a transformer a distribution station, is provided, which cell comprises at least one triphase, sealed bushing for connection with input cables, a tripolar circuit breaker with pneumatic autoblasting, for example a gas-blast circuit breaker, a tripolar earth disconnecting switch, and a set of bars, the cell being divided into two compartments which are sealed in respect of one another and each one in respect of the outside, one of the compartments comprising the set of bars and the other comprising the remainder of the equipment, the two compartments being separated by a tight partition provided with three hollow, cylindrical isolating bushings, wherein the bushings serve as circuit breaker blasting cylinders and as bar supports.

Such an arrangement ensures perfect reliability.

It is possible to fill or empty the compartments independently of one another, a fact which facilitates any interventions inside the one and the other of the compartments of the cell. A single fault cannot spread and create a more serious fault.

For a better understanding of the present invention and to show how the same may be carried into effect, reference will now be made, by way of example, to the accompanying drawings in which: Figure 1 is a longitudinal, diagrammatic view through a vertical section of a cell according to the invention; Figure 2 is a transverse, diagrammatic view through a vertical section in accordance with line Il-Il of Figure 1, but in the open position; Figure 3 represents a front view of a unit of three cells mounted on a support; Figure 4 is a left-hand view, partially through a section, of the unit of Figure 3; Figure 5 is a right-hand view of the same unit; Figure 6 is an electrical diagram of the unit represented in Figures 3, 4 and 5; Figure 7 is a view of a cell, partially sectioned, showing the connecting device for the set of bars;; Figure 8 is a front view, partially removed, of a unit of two cells provided with plugs which can be unplugged.

The cell represented in Figures 1 and 2 comprises a lower compartment 1 and an upper compartment 2, both sealed in respect of the outside and in respect of one another.

The compartments are filled with gas having great dielectric strength, such as sulphuric hexafluoride SF6, which allows the cell to be made with smaller isolating gaps than if the cell was filled with air at atmospheric pressure.

The lower portion of the lower compartment 1 is closed by an isolating plug 3 provided with three extensions 11, 12 and 13 provided inside with metal rods 21, 22, 23. Each rod is connected by one end to the input cable (not shown); its other end forms a fixed contact of the tripolar circuit breaker with pneumatic autoblasting.

A tripolar circuit breaker-disconnecting switch comprises three cylinders 31, 32, 33 which serve on the one hand as electrical bushing between the compartments 1 and 2, on the other hand as support for the bars 41, 42, 43 of the cell, and finally as blasting cylinder for the circuit breaker.

There is discernible in Figure 1 the movable unit of the circuit breaker, comprising buses 51,52,53 supported by sliding cylinders 61, 62, 63 which themselves hold sets 71, 72,73 of contact fingers connecting the fixed contacts 21, 22, 23 and fixed rods 81, 82, 83 inside the cylinders 31, 32, 33. A set of rods 91, 92, 93 connected to a shaft 10, by way of arms 94, 95 and 96 allows tripolar operation of the circuit breaker. The end of the shaft is connected to a driving mechanism 14 provided with a spring 1 5 ensuring a certain interrupting capacity and a closing capacity.

The lower compartment also contains an earth disconnecting switch comprising an arch 99 provided with pincers 101, 102, 103 cooperating with the rods 21, 22, 23. In Figure 1 the arch 99 is represented by a broken line in the closed earth disconnecting switch position and by a solid line in the open disconnecting switch position.

The arch is jointed and connected to a control mechanism 24 comprising a spring 25 which provides it with the ability of closing on short circuiting.

The earth disconnecting switch is shown in an opening position in Figure 2.

The lower compartment 1 is provided with a safety plate 1 6 which breaks in the event of excess pressure inside; the gases then escape through a flue 1 7 which, furthermore, protects the environment from the fragments of the plate 1 6.

The lower compartment 1 contains pellets such as 1 8, for example of titanium oxide, connected to the rods 21, 22, 23 and forming high tension capacity to supply lamps which indicate the presence of tension.

The upper compartment 2 comprises flanges such as 19 which allow either the compartment to be closed by a tight plug, orto be connected with the corresponding compartment of another adjacent cell.

Figures 3, 4 and 5 represent an assembly of three cells, viewed from the front, the right and the left respectively. Figure 6 represents the corresponding electrical diagram.

Cells 121A, 121 B, 121C rest on sheet metal supports 122A. 122B, 122C piaced on the ground.

Cells 121Aand 121B are connected to the input cables 151,152,153 for the cell 121 A and 157,158,159 for the cell 121 B.

The cell 121 C is connected at the output with a transformer T (not shown) by fuses 1 31 C, 1 32C, 1 33C (visible in Figure 4) and by cables 1 54, 1 55, 156.

Visible in the diagram of Figure 6 are the circuit breaker-disconnecting switches 141 A, 1 42A, 143A; 141 B, 142B, 143B; 141C, 142C, 143C; and the earth disconnecting switches 1 71 A, 172A, 173A; 172B, 172B, 173B; 171C, 172C, 1 73C located upstream of the input circuit breaker-disconnecting switches and downstream of the output circuit breaker-disconnecting switch and aiso the earth disconnecting switch 174, 175, 1 76 located downstream of the fuse.

The three cells are interconnected by way of bolts, adhesion between flanges ensuring that they are gas-tight.

One of the advantages of the solution is the fact that the set of bars compartment, being independent of the circuit breakers can be filled with gas last, following assembly, by a valve fixed to one of the plugs 3, which, furthermore, allows a fourth module to be added without emptying the other compartments.

The unit formed by the cells and their supports being metal, it is no longer necessary to provide them with metal casings, a fact which reduces the bulk of the station in comparison with stations of a known type.

Another advantage is the fact that there is no longer any element around the point of attachment of the cables, a fact which facilitates the connection of the latter and allows the width of the cell support to be greatly reduced.

For matters of reduced heating and simplicity of connection, the fuses are placed in the air.

Figure 7 illustrates the ease of extension of a unit as a result of pincers 1 68 placed at the end of the set of bars 40 of the cell 122D, which clip onto the set of bars of the adjacent cell; obviously, this operation makes it necessary to empty the compartment of the SF6 gas and to fill it afresh after connection, but without any particular precautions, the gaps in the set of bars admitting a mixture of air/SF6 gas; it is not necessary to evacuate the compartment before filling it with SF6 gas.

The input connections of a cell unit 1 22E, 1 22F can be formed as shown in Figure 8 with the aid of plugs such as 160 which can be unplugged; the output connections can also be formed by plugs 161 which can be unplugged and which are joined to the bushings 1 62 which are fixed to the output plug of the set of bars compartment of the cells.

Claims (2)

1. A three phase cell adapted to cooperate with two similar three phase cells and a transformer to form a distribution station, the three phase cell being divided into two compartments which are sealed in respect of one another and in respect of the outside, one of the compartments containing a set of bars and the other compartment containing at least one three phase sealed bushing for connection with input cables, a tripolar circuit breaker with pneumatic autoblasting, and a tripolar earth disconnecting switch, the two compartments being separated by a tight partition provided with three hollow, cylindrical isolating bushings wherein the hollow cylindrical bushings serve as circuit breaker blasting cylinders and as supports for the bars.

2. A three phase cell substantially as hereinbefore described with reference to and as shown in the accompanying drawings.