FR2735914A1 - Medium tension gas-insulated electricity distribution installation - Google Patents

Abstract

The medium tension distribution installation has two switching modules (121,131) each comprising a circuit breaker and/or an isolator. The transformer (100) is supplied by two incoming cables (101,102) and protected by a circuit breaker (105). The two switching modules are placed side-by-side. The first (121) has one of the cable inlets (101) in series with the isolator and the circuit breaker. The second module has the second cable inlet in series with an isolator connected to the common point between the isolator and circuit breaker of the first module. The second module has in addition a third isolator (106) in series with the circuit breaker and connected by bars (133) to the transformer primary.

Description

MEDIUM VOLTAGE DISTRIBUTION EQUIPMENT
The present invention relates to medium voltage distribution equipment.

For around twenty years, cut-off devices in sulfur hexafluoride (SF6), after having conquered the field of very high voltage, have established themselves in medium voltage (15 to 72 kV) by providing some advantages:
- ease of isolation and cutting,
- limitation of erosion and wear of the breaking contacts, which leads to an increase in the longevity of the devices.

 These advantages must be weighed against the many disadvantages encountered by the operators of the devices.

 A distinction can be made between shutdown equipment with air isolation and cut-off in SF6, and so-called "reduced pitch" equipment.

1. Interruption equipment with isolation in air and cut in SF6
The operators have seen disappear (in the case of work in the cell):
- visible cutoff or visible isolation,
- automatic reconstitution of metallic envelopes,
- the standardized cut-off distance in air, which has been replaced by a reduced distance inside an insulating chamber,
- the safety ring to earth at the cut-off interval.

 The manufacturers have been forced, for safety reasons, an earthing switch which does not reduce the price of the assembly and which does not constitute for the operator absolute safety in the event of priming in the room cut-out of arc drawing by SF6.

 Whatever the manufacturing precautions and the quality of the tests, the risk of leaking insulating gas exists and constitutes a danger for the devices.

 All manufacturers have tried to reduce the dimensions of the cells, which means that there is less space for the cable heads.

 Despite the use of SF6, the cells have the same shapes and overall the same dimensions required by the obligation to add a cut-off distance to a distance to ground. In short, most cells of the indicated type are not compact at all.

 The devices in these cells are generally made with synthetic resin envelopes. As a result, for envelopes subjected to pressures of several hectopascals (circuit breakers), risks of ignition and explosion of the devices, which are moreover more and more often installed in public places. The increasingly restrictive safety rules, and ecological concerns can lead to questioning this technique.

2. Equipment known as "with reduced step1
The manufacturers are moving towards reduced bulk materials immersed in SF6.

 It turns out that replacing the equipment referred to in the previous chapter with equipment in which the apparatus is placed in the SF6 is not as economical an operation as it seems at first glance.

 In fact, it is not possible to produce in this technique all the equipment necessary in all the existing voltage ranges. The series are therefore reduced, which strikes their cost price.

 The cost price of the materials in SF6 is high mainly because of the welds to be made to obtain the seal.

 The risks are higher in service, in particular the risks of leakage which are proportional to the lengths of the welds.

 There are no longer any internal partitions between cells: this leads to risks of priming.

 No isolation maneuver is controllable; it is not possible to visit and dismantle the equipment per cell unit.

 An object of the invention is to provide prefabricated medium voltage equipment with reduced overall dimensions, reduced cost price, easy use and maintenance and without risks for the personnel, safe operation, long service life. .

 The equipment of the invention is based on the use of cells with self-disconnecting circuit breakers and self-disconnecting switches.

 There has been described, in French patent application No. 91 14 311 filed on November 20, 1991, a self-disconnecting circuit breaker whose characteristics are recalled now.

 Such a self-disconnecting circuit breaker comprises, for each pole, an insulating bushing (or insulating barrel) enclosing a vacuum interrupter, the crossing comprising at a first end a first contact connected to a first terminal of the vacuum interrupter and to a second end a second contact connected to a second terminal of the vacuum interrupter, the bushings being fixed to a metal profile along which is disposed an operating shaft common to the vacuum interrupters and actuated by a control operation of the vacuum interrupters contained in a box secured to the profile, the latter being actuated in rotation to ensure the sectioning function.

 Such a circuit breaker has made it possible to produce a module with a busbar, marketed by the Applicant under the registered trademark VISAX. Reference may be made to French patent application No. 93 09 280 of July 28, 1993.

 Such a module is shown seen from the side, in elevation, in Figure 1.

 There is a metal box 1, carrying a metal drawer 2 containing the axis serving as a support for three barrels 3A, 3B, 3C insulators each containing a vacuum bulb and constituting the poles of a three-phase circuit breaker referenced globally DAS and ensuring the function module shutdown. The vacuum ampoules are controlled by a mechanism placed inside a box 4. This box is integral with the support axis of the insulating drums. Each drum has two end contacts; the first contacts 5A, 5B, 5C ensure contact with a busbar 7A, 7B, 7C emerging from an insulating block 9 constituting a roof for the cell; the second contacts 9A, 9B, 9C provide contact with multifunctional bushings 10A, lOB, 10C, which each contain a current measurement toroid and which are connected to cable inlets 12A, 12B, 12C.

 The control mechanism contained in the housing 4 performs the "cut-off" function by causing the vacuum bottles to open. The rotation of 900 of the barrel support axis, and of the control unit which is integral with this axis, ensures the sectioning function of the module.

 Note that thanks to the insulating block 9, the cable compartment is completely isolated from the busbar compartment.

 The invention also makes use of a self-disconnecting switch. Such a switch is described in the French patent application entitled "Auto-disconnector switch" and filed on the same day as the present patent application.

 This three-phase auto-disconnector switch is characterized in that it comprises three insulating bushings each containing a vacuum bulb, the bushings being integral with a beam which can pivot inside a chassis, the vacuum bulbs being operated by by means of a control shaft associated with an operating mechanism, the beam being secured to a member for rotating by spring passing neutral, the switch being opened by the successive operation of the control shaft and the member for rotating the beam.

 An exemplary embodiment of a self-switching switch is described with reference to FIGS. 2 to 4.

 FIG. 2 is a perspective view of a self-disconnecting switch in which the operation of the poles is ensured by a push-pull system, FIG. 3 is a partial view in elevation of the self-disconnecting switch of FIG. 2 and FIG. 4 is a front view of the auto-disconnector switch of FIG. 2.

 In FIG. 1, the reference 21 designates a tubular frame, provided with rollers 22, intended to be placed, in the manner of an extractable drawer, in a cabinet not shown.

 A horizontal beam 24 is articulated by its two ends 24A and 24B to plates 25A and 25B fixed to the chassis, so as to be able to carry out a rotational movement of 900 around its longitudinal axis. The beam 24 is at ground potential.

 To the beam 24 are fixed three insulating bushings 27A, 27B and 27C, each containing a vacuum interrupter.

Each of these crossings constitutes a pole of the switch. For clarity of the drawing, the crossing 27C has only been shown partially and in dashed lines; only the bulb 29B of the bushing 27B has been shown.

According to a characteristic of the invention, the vacuum interrupter is chosen, from commercial ampoules produced economically in large series, according to its ability to cut the nominal current of the device in which the switch is installed, without being concerned of the voltage withstand between the terminals of the bulb. This voltage is zero when the bulb has its contacts in the closed position.

The voltage withstand is ensured by the pivoting of the poles, as will be explained below. For example, to cut 400 or 630 amperes under the single voltage corresponding to a 24 kV network, we will choose the cheapest and the smallest of the bulbs usually used:
- for a recloser 11 kV or,
- for a 7.2 kV or 3.3 kV or 1 kV contactor.

 Sheltered from the beam 24 is disposed a shaft 30 for opening and closing the poles; in the example of FIG. 1, this tree 30 is a tree of the "rickshaw" type, since it acts by moving in translation along its own axis, under the action of an electro coil -magnet 32; the pole control mechanism is explained with reference to pole 27B: the movable rod 32B of the vacuum interrupter 29B is connected to a first end of a metal rod 33B articulated around an axis 34B secured to the bushing 27B; the second end of the connecting rod 33B is articulated at a first end of an insulating connecting rod 35B capable of withstanding the operating voltage of the device; the second end of the insulating rod 35B is articulated in a light 37B from a first end of a metal bracket 38B, the second end 39B of which is articulated on the control shaft 30. The bracket 38B pivots about an axis 40B secured to the beam 24. The translational movement along its axis of the shaft 30 causes the rotation of the bracket 38B and this movement is communicated to the control rod 32B by the connecting rods 35B and 33B.

 To allow the necessary upward movement of the shaft 30, it is provided, on either side of the appropriate articulation poles 42 and 43. Note that the shaft 30 preferably has a rectangular section in its part between the joints, to allow easy fixing of the brackets; on either side of these joints it preferably has a circular shape, to slide freely through the plates 25A and 25B.

 It will be noted that the control shaft 30 for operating the bulbs is housed inside the joints of the beam 24, the shaft 30 moving in translation completely independently of the rotational movement of the beam 24.

 The pole 27B has a first socket 44B cooperating with a current inlet 45B, and a second socket 46B cooperating with a bar 47B. The other poles have the same sockets cooperating with the same homologous elements. Insulating covers such as 49C provide insulation between the poles.

 The operation of the switch is as follows.

OPENING
The pole is in the configuration of Fig. 2
The coil of the electromagnet 32 is excited, which has the effect of moving the shaft 30 in traslation, causing the opening of the vacuum ampoules. Immediately, or after a determined delay, the beam 24 is suddenly pivoted to 900, which causes the poles to be cut.

As soon as the passage through neutral is carried out, at the latest when the sectioning this sectioning is completed, the supply of the electromagnet is stopped; under the effect of atmospheric pressure, the vacuum ampoules close.

CLOSING
It suffices to cause the rotation of the beam 24 by 900, in the opposite direction to that of the opening.

 We will now describe, with reference to FIGS. 2 to 4, the mechanism making it possible to cause the sudden rotation of the beam 24.

 A cam 50 is secured to the beam 24 by a tube 51 passing through the plate 25A in which it can pivot freely; we note that inside this tube passes the shaft 30 for operating the poles. We denote by O the trace of the axis of rotation of the cam 50.

The cam 50 is articulated at a first end A of a spring 50A which is kept compressed when the switch is in the closed position. The second end
B of the spring 50A is fixed to the plate 25A. When the switch is in the closed position, the spring pushes the cam in the direction tending to rotate it counter-clockwise. The angle between the axis AB of the spring 50A and the line AO is slightly less than 180 degrees of angle.

 The cam is kept stationary by a lug 52 fixed to a nut 53 displaceable in translation on a threaded rod 54 which can be driven in rotation by a motor 55; the nut 54 is immobilized in rotation by slides 56 and 7; the lug cooperates with a first shoulder 50 'of the cam, which is provided with a second shoulder 50 ".

The operation is as follows:
immediately after the poles open, or with a given delay, the motor 55 is rotated, causing the lug 52 to move to the right of the
Fig.3, which rotates the cam 50 clockwise. As soon as the line AB exceeds the neutral line, the spring 50A suddenly relaxes and causes the cam and all the mobile assembly which is integral with it to rotate rapidly, that is to say beam 24 and poles.

 The sectioned position is shown in dashed lines in FIG. 3.

 The switch is closed by operating the motor in the opposite direction to the direction used for opening; the lug, in abutment on the shoulder 50 ", drives the cam anti-clockwise, until passing neutral, with compression of the spring 50A; after which the lug is brought back into the position in abutment lug 50 ', ready for a new interruption.

 The subject of the present invention is a medium-voltage distribution equipment characterized in that it comprises at least two modules each comprising at least one self-disconnecting circuit breaker and / or at least one self-disconnecting switch.

The invention will be clearly understood on reading the description below of various embodiments of the invention, with reference to the appended drawing in which:
FIG. 1 is an elevation view of a module with a busbar with a self-isolating circuit breaker,
FIG. 2 is a perspective view of a self-disconnecting switch in which the operation of the poles is ensured by a push-pull system,
FIG. 3 is a partial view in elevation of the auto-disconnector switch of FIG. 2,
FIG. 4 is a front view of the auto-disconnector switch of FIG. 2,
FIG. 5 is an electrical diagram of a circuit for protection by a circuit breaker of a transformer,
FIG. 6 is an elevation view of the protection group of the previous diagram produced by means of the modules of the invention,
FIG. 7 is an elevation view of a protection group of a transformer by switch and circuit breaker,
FIG. 8 is an elevation view of a kiosk type station,
FIG. 9 is a top view of an underground MV / LV station,
- Figure 10 is an elevational view of an MV / LV kiosk station for the exterior.

 FIG. 5 represents the electrical diagram for the protection of a low-voltage medium-voltage transformer (abbreviated hereinafter: MV / LV) 100 the primary of which can be supplied by two cable inlets 101 and 102 (looping). The circuit includes two disconnect switches 103 and 104 allowing the routing of one or the other of the cable arrivals, a protective circuit breaker 105 and an isolation switch 106 of the transformer 100. The current is measured in each of the phases by current transformers 107, the voltage by potential transformers 108 protected by circuit breakers 109. Disconnectors 111 and 112 make it possible to earth the cable arrivals 101 and 102.

Figure 6 shows how the diagram in Figure 5 can be achieved using two standard modules of the type
VISAX, referenced 121 and 131, to which is added a box 132.

 The module 121 includes the arrival of cables 101 with the earthing switch 111 and the voltage transformer 108 provided with its circuit breaker 109, a drawer 103 equipped with a switch-disconnector, and a drawer 105 equipped with a circuit breaker -sector. The module 131 includes the arrival of cables 102 with the earthing switch 112, a drawer 104 equipped with a switch disconnector and a drawer 106 equipped with a disconnector, mounted at right angles to the preceding drawers.

 The box 132, which surmounts the transformer 100, contains a link by bars 133 connecting the disconnector switch 106 of the module 131 to the primary of the transformer 100, and a disconnector 134 for earthing the medium voltage terminals of the transformer 100.

 The current transformers 107 (one per phase, toroid or wound) are maintained by isolators 107A fixed to the common ceiling of the modules 121 and 131.

 We therefore produced, by means of two VISAX modules, a reduced size protection group, ensuring all the usual functions with security and ease of operation (all commands can be automated and programmed) and maintenance (easy access and safe, all the extractable elements can be visited with the station remaining energized).

 Note the absence of a cable connection to the transformer, all the connections being made by bars.

 Figure 7 is an alternative embodiment of a transformer protection group; the elements common to this figure and to Figures 5 and 6 have been given the same reference numbers.

 Here again, the group is produced by means of two VISAX modules 121A and 131A.

 The module 121A contains the same elements as the module 121 in FIG. 6, except that the drawer 105 is replaced by a drawer 105A fitted with a switch-disconnector.

 The module 131A is provided with a drawer 106A equipped with a switch-disconnector capable of cooperating with the drawer 104, and connected to the transformer 100 by a circuit breaker 141 (fuses) placed in the box 132.

 Optionally, the switch-disconnector 105A is connected to a cable outlet 143 connected to a satellite transformer not shown.

 The group, consisting of two VISAX cells, has the same advantages of compactness and ease of operation as the group of FIG. 6.

 The group can be placed on the ground and protected by a concrete enclosure 145.

 As a variant, the group can be placed in the basement, and in this case the transformer can be extracted from the top.

 We observe the ease with which the fuses are accessible. Fuses are normally air-cooled.

 Compared to the cells of the prior art, the group described in FIG. 7 has the advantage of having a direct connection of the transformer by bars, which makes it possible to eliminate the dry cables and their connections. This results in savings in implementation, greater operating safety and ease of maintenance.

 In the case where the transformer has its own integrated circuit breakers, the circuit breakers 141 are replaced by simple removable bars, for example thin copper tubes.

 The vacuum switches used generally have significant breaking powers, which results in the advantage of coordinating these switches with circuit breakers; these coordinated associations endowed with great endurance can in some cases replace the more expensive self-disconnecting circuit breakers. This replacement is particularly advantageous in the case of an installation in which the ratio of the value Icc of the short-circuit current to the value In of the nominal current of the feeder is very large.

 The self-disconnecting switches described in the preamble to this memo and which are mounted in all positions, horizontal and vertical in particular, allow the creation of "kiosk" stations.

 Such a kiosk station is shown in FIG. 8. and can be indoor or underground.

 There is a transformer 150 which can be supplied to the primary by two cable inlets 151 and 152.

The transformer usually includes its own 150A circuit breaker.

 The switching is carried out by means of three modules 161, 162, 163 each containing a drawer with switch-disconnector. The modules are arranged so that the switch-disconnectors 171, 172 and 173 are star-shaped.

 The modules 171 and 173 include insulators 174 and 175 maintaining the arrivals of the cables 151A and 152A and carrying the sockets or connection bars to the switch-disconnectors 171 and 173. The references 176 and 177 designate the earthing switches of the heads cables. Reference 178 designates the earthing switch of the transformer primary. The connection between the switch-disconnector 172 and the primary of the transformer is ensured by bars 179 (which can be replaced by a circuit breaker in the case where the transformer does not have its own circuit breaker).

 A great advantage of this construction is that the connection between the various switch-disconnectors does not require any busbar, since they are connected by a triple point. The switch-disconnectors placed in the drawer in the VISAX type modules are all extractable, even under voltage. If all the modules are mounted on 180 feet, the transformer can be made extractable without dismantling the cables.

 The floor area of the substation thus produced is minimal.

The station is placed in a concrete tank 181. The low-voltage equipment connected to the secondary constitutes a low-voltage switchboard which can be placed behind the station along the length of the transformer.

We find the advantages inherent in switch disconnectors as described in the preamble:
- air isolation,
- sectioning by rotation,
- automatic reconstitution of the metallic envelopes whatever the access point considered which is otherwise earthed.

 The devices described above, namely self-disconnecting circuit breakers and self-disconnecting switches, allow very simple MV / LV stations to be produced.

 Fig. 9 shows a top view of an underground MV / LV substation.

 There is a cylindrical concrete tank 200, which can receive a circular cover, not shown.

The assembly is designed to be buried and support the passage of heavy goods vehicles on the surface.

 The tank has an opening 201 closed by a grid for ventilation of the station and an opposite opening 202 for access to the low-voltage cables 203.

 The transformer is placed at the bottom of the tank and we can see the trace 205 in the figure. The transformer is supplied by two arrivals of medium voltage cables 211 and 212. Above the transformer is arranged the medium voltage switchboard 215, produced for example by means of two VISAX modules as has been described with reference to FIGS. 6 and 7. The low voltage switchboard 216 is arranged above the medium voltage switchboard with the low voltage switches 217 on the operating front panel.

 The medium-voltage transformer-panel assembly and low-voltage panel can be removed from the top after removing the cover.

 An operating panel 218 is placed above the transformer, at the bottom of the medium voltage switchboard.

 The transformer heats electrical equipment.

Ventilation is ensured by air circulation around the devices between the wall of the tank and the devices.

 The substation is flooded to the top of the transformer; a manhole, opening onto the operating floor, gives access to the operating front panel (medium voltage maneuvers and low voltage switches).

 It should be noted that this type of post can be carried out in a semi-buried post or above ground. In this case, the station receives a conical or flat roof with natural ventilation openings. Two doors are fitted opposite the short sides of the transformer where the medium voltage and low voltage operating faces will be located.

 One of the doors on the medium voltage side can open enough to allow the isolated transformer to be removed by sectioning on the medium voltage side and the low voltage side.

 In this case, the medium voltage switchboard is placed on legs or on supports integral with the concrete tank.

 Figure 10 is an elevational view of an MV / LV kiosk station for outdoor use.

 It comprises, on a concrete base 220, a concrete tank 220A comprising two doors 221 and 222 facing each other and a cover 223. A transformer 205 rests on the base and can be evacuated by the front door 221.

 The transformer is supplied as described with reference to FIGS. 5 to 7. One distinguishes one of the loop supply cables from the transformer, which comprises a second cable not visible in the figure.

Above the transformer are placed two modules
VISAX 227 and 228, realizing the medium voltage supply in loop of the transformer as described above, with its protection by circuit breaker or by switch associated with a circuit breaker. Advantageously, the modules are fixed to the concrete shell by means not shown, in order to allow the extraction of the transformer without displacement of the modules.

 Reference 230 designates the low voltage compartment, with its protections 231 and its output cables 232.

 The modules 227 and 228 are remotely controlled and maneuverable manually as a backup by the front door 221 which is equipped with a ladder 221A.

 The invention is not limited to the application examples described and shown.

Claims (10)

1 / Medium voltage distribution equipment characterized in that it comprises at least two modules (121, 131) each comprising at least one self-disconnecting circuit breaker (105) in the drawer and / or at least one self-disconnecting switch (103, 104 , 106) in drawer. 2 / Distribution equipment according to claim 1, characterized in that it comprises a transformer (100) supplied in a loop by two cable inlets (101, 102) and protected by a circuit breaker (105), and two modules (121, 131) arranged side by side, a first module (121) comprising in particular one (101) of the cable inlets, in series with a first self-disconnecting switch (103) and with a self-disconnecting circuit breaker (105), a second (131) module comprising the other (102) cable entry in series with a second self-disconnecting switch (104) electrically connected to the common point to the first self-disconnecting switch (103) and to the self-disconnecting circuit breaker (105) module further comprising a third self-disconnecting switch (106) in series with said self-disconnecting circuit breaker and connected by bars (133) to the primary of said transformer. 3 / Distribution equipment according to claim 1, characterized in that it comprises a transformer (100) supplied in a loop by two cable inlets (101, 102) and protected by a circuit breaker (141), and two modules ( 121A, 131A) arranged side by side, a first module (121A) comprising in particular one (101) of the cable inlets, in series with a first auto-disconnector switch (103), a second (131A) module comprising the other (102) cable entry in series with a second self-disconnecting switch (104) and with a third self-disconnecting switch (106A) electrically connected by a first terminal to the first self-disconnecting switch (103) and by a second terminal to the transformer (100) through said circuit breaker (141). 4 / Equipment according to claim 3, characterized in that said first module (121A) further comprises a fourth switch-disconnector (105A) in series with said first switch-disconnector (103) and connected by a cable (143) to a second transformer. 5 / Equipment according to claim 1, characterized in that it comprises a transformer (150) supplied by two cable inlets (151, 152), and a first (161), a second (162) and a third (163) modules arranged side by side above the transformer, said modules each comprising a self-isolating switch (171, 172, 173), said first module (161) further comprising one (151) of the cable inlets connected to a first terminal of the auto-disconnector switch of this module, said third module (163) further comprising the other (152) cable inlet connected to a first terminal of the self-disconnector switch of this module, a first terminal of the self-disconnecting switch of the second module (162) being connected by bars (179) to the transformer (150), the self-disconnecting switches being arranged in the modules so as to be connected in star by their second terminal. 6 / Equipment according to claim 1, comprising a cylindrical tank (200) inside which is disposed a transformer (205) surmounted by a medium voltage assembly (215) providing a loop supply by two cable inlets ( 211, 212) arranged on either side of the transformer, the medium voltage assembly (215) itself being surmounted by a panel (216) containing low voltage equipment. 7 / Equipment according to claim 6, characterized in that the tank is buried and provided with a cover. 8 / Equipment according to claim 6, characterized in that the tank is semi-buried and provided with a roof. 9 / Equipment according to claim 1, characterized in that it comprises a tank (220A) disposed outside and provided with a cover (223) and inside the tank, a medium voltage switching assembly for the 'loop power supply by two current inlet (225) of the transformer, said assembly comprising two modules (227, 228) superimposed and surmounting said transformer, and a low voltage switchboard (230). 10 / Equipment according to claim 9, characterized in that the tank comprises two doors, one (221) allowing the extraction of the transformer and allowing access to the medium voltage assembly (227, 228), the other, (222) diametrically opposite the first and giving access to the low voltage switchboard.