Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
  • H01F27/00—Details of transformers or inductances, in general
  • H01F27/24—Magnetic cores
  • H01F27/26—Fastening parts of the core together; Fastening or mounting the core on casing or support
  • H01F27/263—Fastening parts of the core together

Definitions

• This invention relates generically to an electrical transformer.
• three-phase transformers in particular those of the so-called “dry” type, generally have three primary windings and three secondary windings mounted on a single core made of ferromagnetic material.
• Dry-type transformers can be further classified as resin-insulated or air-insulated, depending on whether or not the coils are incorporated with an insulating coating, which usually consists of a thermosetting resin; this coating is necessary especially when the transformer is used in highly polluted environments.
• windings are electrically connected, depending on the ratio of the linked voltages to be obtained, by means of conductive connection rods positioned laterally on the coils.
• the frame usually comprise armatures, consisting of metal sheets or profiles, positioned in correspondence with the yokes and designed to protect them, so as not to leave them totally exposed to external agents; the armatures are fixed to each other by means of suitable fastening means, such as tie rods.
• the fastening means are positioned near the side portions of the opposite metal profiles; however, this generates a drawback during the fastening phase of the profiles themselves, which, because they are elastic, bend after tightening the tie rods due to the presence of the columns.
• tie rods which are capable of tolerating such stresses in prior art transformers, due to the method of joining between columns and yokes which is implemented by means of interfaces cut at 45°; this method reduces the losses in the core and improves the noise level compared to cores built by cutting at 90°.
• rigid rods are used to discharge the weight of the transformer during lifting from the upper to the lower armature.
• the aim of the invention is therefore to make an electrical transformer with armatures with improved strength and resistance characteristics compared to the prior art, through the positioning of fastening means in the central area of the armatures.
• a further aim of the invention is to provide a solution to the problem of lifting and transporting electrical transformers, avoiding overstressing the tie rods.
• an aim of the invention is to make an electrical transformer, in particular having a core assembled by cutting at 45°, which ensures the pressing of the core by means of transverse tie rods, and not by means of lateral tie rods as known in the prior art.
• Another aim of the invention is to allow the production of transformers in a simple and fast way.
• FIG. 1 An electrical transformer 100 used with three-phase voltage current is shown in Figures 1 and 2 ; coils 1, which enclose columns 2 of the ferromagnetic core, are visible.
• the primary and secondary coils or windings 1 are connected to each other by the electrical connections 5.
• first housings or openings 51 are made both on the upper armature 41 and on the lower armature 42, for pressing the yokes 31, 32 by means of the first fastening means or tie rods 61, and second housings or openings 52 for pressing the columns 2 by means of second fastening means or tie rods 62.
• tie rods 61, 62 for each armature, and preferably at least one is installed at each column 2, in order to obtain a more uniform distribution of the stresses; in particular, a number of second tie rods 62 may be provided equal to two for each column 2, one connected to the upper armature 41 and one connected to the lower armature 42.
• the tie rods 62 advantageously make it possible to uniform the clamping force exerted by the sheets of the armatures 41 and 42 on both the yokes 31 and 32 and on the columns 2, avoiding any deformation of the armatures.
• the first and second tie rods 61 and 62 are therefore held in tension by suitable bolts and/or tightening nuts 610 and 620, and are inserted in the respective first and second housings 51, 52.
• first and second housings 51, 52 are through holes and made respectively:
• the side tie rods are absent; they are replaced by a total number of ten between first and second tie rods 61 and 62, housed in their respective housings 51 and 52.
• each yoke 31 and 32 there are two housings 51, designed to house the tie rods 61 for pressing the armatures 41 and 42 on the yokes 31 and 32.
• the main function of the tie rods 61 is to press the core using the armatures 41 and 42.
• each column 2 On each column 2, on the other hand, there are two housings 52, at its upper and lower ends.
• the housings 51 and 52 are openings passing, respectively, through the yokes 31, 32, and through the columns 2.
• the positions of the housings 51 and 52 that is, of the tie rods 61 and 62, are not aligned with each other, but lie substantially on two different parallel lines.
• the housings 52 in which the tie rods 62 are inserted do not overlap the joints between the yokes 31, 32 and the columns 2, thus avoiding harmful interference in the operation of the core.
• the tie rods 61 and 62 of the transformer according to the invention pass through and advantageously provide a transformer which is structurally much more rigid than the conventional ones equipped with tie rods located in the side portion of the armatures 41, 42; in fact, according to the invention, it is impossible to obtain connections which are not properly tightened or to incur deformations of the sheets of the armatures 41, 42 deriving from the pressing force.
• Figures 4, 5 , 6A and 6B show the particular arrangement of the housings 51 and 52 with respect to the joining interfaces between columns 2 and yokes 31, 32 of the transformer 100.
• Respective spacers 210, 310 are also positioned on the opposite faces of the columns 2 and the yokes 31, 32, near the tie rods 61, 62, in contact with the armatures 31, 32 and the core itself.
• the same measures are adopted in the lower portion of the core, which is not described here for sake of brevity.
• a support 421 for the low voltage coils installed at the base of each column and fixed to the lower armature 32.
• the position of the housings 52 can be moved without altering the pressing, and without causing deformation of the armatures.
• reinforcement profiles 10 positioned on the sides are visible, which advantageously connect the ends of the upper armature 41 to those of the lower armature 42; the above-mentioned reinforcement profiles 10 are advantageously connected to the armatures 41, 42 by means of suitable connection means 101, for example, bolts and/or nuts.
• the reinforcement profiles 10 can preferably be made of metallic material with a U-profile, and have the function of replacing the rigid bars used in the prior art for lifting the transformer.
• Eliminating the rigid bars also eliminates the need to interpose sheets of insulating material which would normally be necessary to insulate them electrically from the column.
• this feature allows the transformer to be lifted easily, without the risk of failure of the armature connections; in fact, if the transformer were secured, by means of the hooks 8, to a lifting device (for example a crane or a gantry crane) to be lifted, most of the weight of the transformer would lie on the armature 42, which in turn would discharge it to the armature 41, being connected to it by means of the reinforcement profiles 10.
• a lifting device for example a crane or a gantry crane
• Figures 7A-7B are cross-sections of the housings 52 and the tie rods 62 used, respectively, for pressing the upper and lower ends of the columns 2.
• the housings 52 pass through and are spaced from the joining area with the yokes.
• Figure 7C refers, on the other hand, to housings 51 and tie rods 6i used for pressing yokes.
• tie rods 61 and 62 are provided with plugs or washers 611, 621 made with a polymeric and/or insulating coating, to prevent contact with the metal of the core of the transformer 100 so as not to alter its magnetic properties.
• the clamping nuts 620, 610 allow for quick and easy adjustment of the pressing force of the tie rods 61, 62 on the armatures, and thus on the core.

Landscapes

• Engineering & Computer Science (AREA)
• Power Engineering (AREA)
• Housings And Mounting Of Transformers (AREA)
• Regulation Of General Use Transformers (AREA)
• Insulated Conductors (AREA)
• Details Of Television Scanning (AREA)
• Coils Of Transformers For General Uses (AREA)

Applications Claiming Priority (1)

Publications (3)

Family

ID=68234171

Family Applications (1)

Country Status (4)

Family Cites Families (7)

• 2019
  • 2019-06-14 IT IT102019000009093A patent/IT201900009093A1/it unknown
• 2020
  • 2020-06-15 ES ES20179920T patent/ES3062060T3/es active Active
  • 2020-06-15 PL PL20179920.2T patent/PL3751588T3/pl unknown
  • 2020-06-15 EP EP20179920.2A patent/EP3751588B1/en active Active

Also Published As

Similar Documents

Legal Events