EP1973127A1 - Live part of an encapsulated transformer equipped with a connection system at one end and modular HV/LV transformer including same - Google Patents

Abstract

The part (12) has a low voltage internal coil contained in an insulation coating in resin, and low voltage terminals located on an end face of the part for connecting the internal coil. A high voltage external coil (20) has a spiral winding (60) between an input and an output contained in the insulation coating. A connection system (30) connects the external coil with an input terminal (22) and an output terminal (24), and located on the end face such that the low voltage, input and output terminals are accessible from the end face.

Description

TECHNICAL AREA

The invention generally relates to the production of power transformers or distribution of electrical energy, single phase or multiphase type shielded coated, in which the electrical connection is facilitated for both high and low voltage.

In particular, the invention relates to an active transformer part provided with a connection system comprising the input / output terminals at one end of this element. Three active parts can be associated with a magnetic circuit to realize a three-phase transformer module, modules can be coupled in parallel to increase the power.

STATE OF THE ART

For the distribution of energy to the public, the mains voltage is usually lowered from the "high voltage" level (between 5 and 52 kV) to a "low voltage" level (less than 1000 V); high voltage / low voltage transformers (HV / LV) allow this modification, at the cost of significant heat exchange. Traditionally, these transformers use mineral oils as insulating and heat transfer fluid.

In particular in order to preserve the environment and to avoid the risk of fire, so-called coated or solid-insulated transformers have been developed in which the concentric primary and secondary windings are each embedded in dielectric molding resin. In addition to electrical insulation, the resin also exchanges heat with the air to cool the transformer. This type of insulator is known in low voltage, and for example for LV / LV transformers as described in US 2,998,583 ; however, its application to high voltage is not directly differentiable, given the difference between dielectric stresses. In particular, the ends of the HV windings, corresponding to the connection terminals of the coils and transformers, can not, unlike the low voltage, be simply anodized, but also require an insulating coating.

An exemplary embodiment of a high-voltage transformer with solid insulation is given in the document WO 98/10447 . As also illustrated in the figure 1E of said document, the active parts of coated transformers comprise, in the insulating coating of the outer coil HT, orifices permitting the passage of the conductor ends of the turns to connect them to other components, so that the coating includes the entry and exit of the windings of turns. Three individual active parts can be associated with a magnetic circuit and with connecting bars to form a three-phase transformer; upper and lower yokes then allow the mechanical maintenance and protection of individual units. The active parts of current coated power transformers are also sometimes shielded at each cell to increase their insensitivity to the environment.

In the prior art, each power step corresponds to a single dry transformer, which is therefore most often manufactured to order from a specification; this type of coated transformer remains expensive. It would be particularly desirable to manufacture "standard" modules, entities that are then to be coupled together according to the power envisaged: such a modularity makes it possible to reduce the manufacturing costs and to adapt the desired power of the transformer by a minimum number of rooms.

It appears, however, that for HT / LV transformers with solid insulation, the connections quickly become problematic and that the assembly on site is complex: the terminals HT of connection, lateral and embedded in the insulator, coated transformers are hardly accessible, and their connection generates minimal spacings between modules that no longer meet certain requirements of congestion processing stations.

In addition, the weight of the order of several hundred kilograms of these transformers does not allow easy handling, especially on site. It thus appears desirable to facilitate the handling operations and to standardize them.

SUMMARY OF THE INVENTION

Among other advantages, the invention aims to overcome the disadvantages of existing coated transformers by setting up a separate connection system remote on one side of the transformer. The connection system preferably located in the upper part of the transformer makes it possible to form several HT / LV transformation benches of variable size and power, with the possibility of modification, for example extension, even after their introduction.

The invention relates to a generally cylindrical active part of HV / LV transformer concentrically comprising an internal coil, advantageously the low voltage winding, provided with its connections to an end face, and an external coil, which comprises on said face. end of a connection system having at least one input terminal and one output terminal. This location facilitates connection procedures. To simplify them further, it is preferable to have two sets of terminals on the connection system.

Preferably, the connection system is an isolated entity that can be secured to the winding of turns, and incidentally to a lower wafer. With this configuration, the parts can be standardized, and the modular structure of the transformer is optimized.

The solidarizations are advantageously carried out in overmoldings or protuberances of the resin, both for the connection system and the coil, or even the lower wafer, in which electrical or insulating connectors can be put in place. One of the connections, for example the "rising" of the output of the coil winding to the connection system, can be achieved via an external connection from the lower end of the coil; advantageously the other connections electric are made directly in the protuberances. It may be advantageous to have other overmoldings on the coil, for example three protuberances at 120 ° with orifices at the ends, some of the protuberances then being intended for example for mechanical stability.

According to another aspect, the invention relates to a three-phase transformer module comprising a magnetic circuit and three active parts connected at their external coil by the terminals of their connection system by means of connecting means.

Such a module can be associated with other identical modules in parallel by said terminals to form a transformation bank in which the useful power is increased. The star or delta coupling is advantageously performed on the last transformer module via its connection system, said system preferably comprising several terminals. This embodiment allows a single star or delta connection of the outer coils for increased power.

BRIEF DESCRIPTION OF THE FIGURES

Other advantages and features will emerge more clearly from the following description of particular embodiments of the invention, given by way of illustration and in no way limiting, represented in the appended figures.

The Figures 1A and 1B schematically illustrate a three-phase transformer module according to the principle of the invention.

The Figures 2A to 2D represent a transformer coil and its various elements according to a preferred embodiment of the invention.

The figure 3 shows the combination of three active parts to achieve a three-phase transformer module according to the invention.

The figure 4 shows a modular transformer according to one embodiment of the invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Although described below with reference to a three-phase transformer, the system according to the invention can also be used in single-phase or any other mode: the skilled person will recognize the advantages of the invention and the changes to be made. The coils and the terminals are advantageously shielded in order to allow a saving of space during a side-by-side installation for the formation of a modular transformation bench.

As schematized in Figures 1A and 1B , a three-phase transformer module 10 comprises a magnetic circuit associated with three active transformer parts 12, which are placed side by side and held by an upper yoke 14. Each active part 12 comprises, around a magnetic circuit core an internal coil, usually the "low voltage" coil provided on the upper face 16 of two LV terminals 18, that is to say a terminal 18p for the phase and a terminal 18 _n for the neutral, for a connection on the LV busbars. The LV coil is surrounded by an HT coil 20.

In order to be able to produce a bank of modular shielded embedded power transformers, according to the invention, a transfer of the connection of the active transformer parts 12 is put in place, and all the terminals are located on said upper face 16 of the module 10 of to facilitate the installation, connection and possible replacement of the module 10 if it is associated in parallel in a transformation bench. It should be noted that even if the top is the most easily accessible area for a transformer whose axis is vertical, it is possible to deport the different connection points at the other end.

Thus, according to the invention, the ends of the outer winding 20 are connected to a set of shielded input and output terminals 22 and 24, which are located on the end face 16 of the active part 12. Tel schematically, the set of terminals 22, 24 is advantageously doubled, so that two input terminals 22 ₁ , 22 ₂ and two terminals of output 24 ₁ , 24 ₂ are available to facilitate connections to the high voltage source, to the next module 10, and the Y or D coupling for the end module of a transformation bench. The complexity of shaping the coating in the insulating resin 26 of the turns of the HT coil 20 is, however, such that a simple transfer of the terminals with respect to the location of the ends of the coil winding HT 20 can not be envisaged, and that the transfer of connections from their lateral outlet to a front location according to the invention causes changes in the design of the coil 20, which can not be considered as a direct transposition of the coil BT.

Preferably, the high voltage connection system is an independent element that can be secured on a coil winding: this solution simplifies the parts to be manufactured and to standardize them; a lower element can then be provided to be secured to the other end of the coil winding. This solution also makes it possible to manufacture the winding of turns in several elements, in particular by the superposition of identical power wafers, an example of which is described in the patent application. FR 07 02010 entitled "Adjustable Primary Voltage Coil for Dry Transformer and HV / LV Transformer Including It ".

In the preferred embodiment illustrated in figures 2 , the different elements for the manufacture of an active part 12 ( Figure 2A ) are represented. Thus, the connection system, or end plate, comprises an annular element 32 ( Figure 2B ) secured to the winding of turns. On the wafer 30, preferably in the same resin as that of the coil 20, are positioned the terminals 22, 24, in this case two input terminals 22 ₁ , 22 ₂ and two output terminals 24 ₁ , 24 ₂ . Each of the terminals 22, 24 is "right", that is to say that it is open on the upper face 34 of the wafer 30 so as to be easily connected from the outside, preferably parallel to the axis of the coil 20. Advantageously, each terminal 22, 24 is made with a connection insert 36 placed in a suitable arrangement 38 of the ring 32, which may be, depending on the desired average size, a protrusion on the upper face 34 or, as shown, a lateral protuberance of the ring 32.

The connection inserts 36 are electrically connected to means for connection to the input and output of the winding of turns to which the system 30 is intended. In particular, an electrical connection 40 is embedded in the resin ring 32 between each terminal 22, 24 and an orifice adapted to receive a connector to the winding. The connection orifice may be lateral, but it is preferable that it be integrated with a lateral protuberance 42, 44 of the ring 32, so that the connection will also be longitudinal parallel to the axis: this system makes it possible to stabilize the stack at the same time as the electrical connection while facilitating installation. Advantageously, the connection orifice of each protuberance 42, 44 does not open into the upper face 34 to isolate the system.

The connection system 30 thus comprises at least two protuberances 42, 44 opening on the face opposite to the connection face 16, that is to say the lower face, for example provided with connection inserts 36, electrically connected to terminals 22, 24 by a line 40. The connection inserts 36 are advantageously identical to those used for the terminals 22, 24 to rationalize the manufacture and storage; the connection protuberances 42, 44 are intended to receive a connector 46 (for example a biconica as illustrated in FIG. Figure 2C ) for electrically connecting the terminals 22, 24 to the input and output of the winding to allow the passage of current.

On the face of the coil opposite the connection system 30 is similarly positioned an end wafer 50, illustrated in FIG. 2D figure which comprises two protuberances 52, 54 suitable for the electrical connection at least; the protuberances 52, 54 are intended to receive a connector for connecting them respectively to the coil winding to allow the passage of current, and directly to the output protrusion 44 of the upper wafer 30, for example via In particular, the protuberances 52, 54 are provided with the same connection inserts 36.

The coil 20 comprises a winding of turns 60 between an inlet and an outlet, usually at each end of the winding, which open laterally on the resin ring 26, preferably each in a protrusion 62, 64 adapted to cooperate with the connection arrangements 42, 52, 54 of the end plates 30, 50. The protuberances 62, 64 are open at each end: an orifice, provided for example with an insert 36 similar to the previous ones in electrical connection with the end of the turns, allows a connection by the two faces of the winding 60.

According to the illustrated embodiment, a transformer coil HT 20 thus comprises a stack of a lower wafer 50 provided with two protuberances 52, 54 and a power wafer 60 provided with a protrusion for the inlet 62 and A protrusion for the output 64. An electrical connector 46, inserted in a protrusion 64 of the coil 60 and in a first protrusion 52 of the lower wafer 50, connects the output of the power wafer 60 to the output 54 of the lower wafer 50. Next, a connection system 30 provided with two protuberances 42, 44 and two terminals 22, 24 is put in place, an electrical connector 46 inserted into the input protrusion 42 and the protrusion 62 connecting the input of the winding 60. A bar 56 connects the output protrusion 44 of the connection system 30 and the second protrusion 54 of the lower wafer 50.

It is clear from this reading of an embodiment that the protrusion system can be replaced by an equivalent. It is further preferred, as illustrated, to add on each element 30, 50, 60 one or more arrangements, for example similar protuberances 48, 58 for mechanically connecting the elements 30, 50, 60 to each other in order to stabilize the assembly, for example by an insulating mechanical connector 66 of the plug type.

According to the preferred embodiment illustrated in Figure 2A a transformer cell 12 of 160 kVA supplying a voltage LV of 230 V comprises a lower wafer 50, a power winding 60 and an upper wafer 30 of the same dimensions as the lower wafer 50. The power winding 60 comprises three protuberances (one being hidden in Figure 2A ) distributed at 120 °, two protuberances 62, 64 allowing access to the inlet and the outlet of the coil winding. The lower wafer 50 comprises three protuberances 52, 58, 58 'distributed at 120 °, at least one, and preferably all three, being electrically connected to a fourth protrusion 54 ("exit" of the turns) diametrically opposite to the one of the other three protuberances 52; the protuberances 52, 54, 58, 58 'open on the same side. The connection system 30 also comprises three first protuberances 42, 48, 48 'to 120 ° and a second diametrically opposite protrusion 44 opening into a face of the system; one of the first protuberances 42 and the second protrusion 44 are electrically connected to two terminals 22 ₁ , 22 ₂ , 24 ₁ , 24 ₂ disposed on either side in protuberances 38 opening on the upper face 34. The HT coil 20 can then be assembled, by interlocking with means of connection 46 electrical or mechanical 66, and a bar 56. Preferably, this nesting is done on site, once the low voltage coil placed around the core magnetic circuit.

According to an advantageous embodiment, the power winding 60 can be realized by the superposition of adjustable slabs, according to the invention described in the patent application. FR 07 02010 .

Three active parts 12 according to the invention may be coupled in a star or in a triangle to form a three-phase transformer 10 illustrated in FIG. figure 3 : the terminals 22 ₁ , 24 ₁ input / output are connected in pairs by a conventional medium or high voltage flexible connection cable 70 overmolded conventional. The low-voltage terminals 18 are connected, in a star or in a triangle, by a set 72 of four 20 x 5 bars separated by insulators ( figure 4 ).

It is also possible to make modules 10 to be coupled in parallel in order to increase the power, for example four times three modules 10 of 160 kVA for a three-phase transformer 80 of 640 kVA partially illustrated in FIG. figure 4 the BT terminals 18 are connected as usual by a busbar 72 to form a module 10, and each module 10 is connected to the others in parallel by a second set of busbars 74. The terminals 22 ₁ , 24 ₁ d The high voltage input / output can be connected two by two by a connection connector 70 to form a transformer block, in particular by the same type of conventional overmolded high voltage flexible cable 70. To make the modular transformer 80, it is also necessary to make a phase connection of the external coils 20.

Thanks to the connection system 30 according to the invention, only one of the modules 10, the end module 82, is coupled in a star or a triangle: in this case it is preferred to use the second terminals 22 ₂ , 24 ₂ , different from the parallel connection terminals, to facilitate connections and reduce the number of industrial references; the use of a T-system on a single terminal 22, 24 is possible. The same cables 70 can be used for the parallel connection and the "star / delta" connection.

Although schematized with an alignment 80 of 10 straight modules, it is possible to stack the modules 10 by "sunset"; any vertical and / or horizontal configuration is possible. Furthermore, in the illustrated embodiment, only three modules 10, 82 of three cells are present, a slot 84 being free: in fact, according to the invention, it is possible, for example following a failure of a module 10, continue to operate the installation by adapting the power and replacing the missing module 10 by a simple connection 86.

• réaliser des bancs de transformation de dimensions et de puissance variables à partir de transformateurs standardisés et donc avec peu de références industrielles ;
• réduire les délais et les coûts de fabrication par l'optimisation de l'outil industriel ;
• réduire les délais de livraison grâce à un assemblage sur des stocks que l'on peut optimiser ;
• réaliser un système permettant d'augmenter la VA locale, notamment en étendant la puissance par rajout de modules si besoin ;
• faciliter le transport et la manutention, les modules pouvant être de taille réduite ;
• faciliter l'installation lorsque l'accès au site est difficile (couloir, escalier, ascenseur,...), en fournissant les différents éléments séparément ;
• réaliser le couplage de l'ensemble des bobines en un seul point ;
• réduire les coûts de maintenance ;
• pouvoir fonctionner en mode dégradé pendant le remplacement d'un module.

The invention thus makes it possible, among other advantages, to:

• realize transformers of variable size and power from standardized transformers and therefore with few industrial references;
• reduce manufacturing time and costs by optimizing the industrial tool;
• reduce delivery times by assembling inventory that can be optimized;
• to realize a system allowing to increase the local VA, notably by extending the power by adding modules if necessary;
• facilitate transportation and handling, modules may be small in size;
• to facilitate the installation when the access to the site is difficult (corridor, staircase, elevator, ...), by providing the different elements separately;
• coupling all the coils at one point;
• reduce maintenance costs;
• can operate in degraded mode while replacing a module.

Claims (10)

Active portion of high-voltage / low-voltage transformer with solid insulation of generally cylindrical shape (12) comprising: - a low voltage internal coil contained in a resin insulation coating; - connection terminals (18) of the inner coil located on an end face (16) of the active portion of the transformer (12) and accessible from said end; a high voltage external coil (20) comprising a winding of turns (60) between an input and an output contained in an insulating coating and a connection system (30) of the outer coil (20) with at least one terminal an input terminal (22) and an output terminal (24); characterized in that the connection system (30) is located on said end face (16) so that each terminal (18, 22, 24) of the active portion (12) is accessible from the end. Active part according to claim 1, wherein the connection system (30) comprises an annular element (32) which can be secured to the winding of turns (60), the terminals (22, 24) being connected to means (42). , 44) of the connection system (30) for electrical connection with the input and output of the winding coil (60). Active part according to Claim 2, in which the entry and exit of the coil winding (60) opens out of the coating in a lateral manner. Active part according to Claim 3, in which the coating of the winding of turns (60) comprises lateral protuberances (62, 64) in which the inlet and outlet open and each provided with a connection device (36) in which means (46) can be positioned to electrically connect the input / output to the terminals (22, 24). Active part according to Claim 4, in which the annular element (32) is provided with at least one protuberance (42) provided with an electrical connection device (36) connected to a terminal and corresponding to a lateral protuberance (62, 64) of the coil winding (60), a connector (46) providing the mechanical and electrical connection between the coil (60) and the connection system (30) by said protuberances (42, 62, 64). Active part according to one of claims 1 to 5 wherein the outer coil (20) further comprises a lower wafer (50) comprising means (52, 54) for electrical connection with the winding exit ( 60) and an electrical connection with the output terminal (24) of the connection system (30). Active part according to one of claims 1 to 6 wherein the connection system (30) comprises two input terminals (22 ₁ , 22 ₂ ) and two output terminals (24 ₁ , 24 ₂ ) accessible from said face of end (16). Module (10) of a three-phase modular transformer (80) comprising a magnetic circuit and three active transformer parts (12) according to one of Claims 1 to 7. Three-phase transformer comprising a module according to claim 8 and three connecting means (70) connecting in delta or star the external coils (20) of the three active parts via the terminals (22, 24) of their connection system ( 30). Three-phase modular transformer (80) comprising a plurality of transformer modules according to claim 8, connection means connecting in parallel the modules (10) to each other via their terminals (22, 24), and three connecting means (70) connecting in a triangle or star, the external coils (20) of one of the modules (82) via the terminals (22, 24) of its connection system (30).

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