FR2579365A1 - HIGH VOLTAGE CAPACITOR - Google Patents

Abstract

HIGH VOLTAGE CAPACITOR, WITHOUT OIL OR GAS INSULATION. THE DIELECTRIC LAYERS IN THE CAPACITOR ELEMENTS A ARE IMPREGNATED WITH A SYNTHETIC RESIN AND THE CAPACITOR ELEMENTS ARE ALSO INSULATED WITH A SYNTHETIC RESIN, BY IMPREGNATION OF THE INSULATING MATERIAL B, C AROUND THE CAPACITOR ELEMENTS 10, WITH SYNTHETIC RESIN 10, PASSAGES THE AIR BEING CENTRALIZED IN THE INSULATING LAYER SURROUNDING THE CAPACITOR ELEMENTS.

Description

High voltage capacitor.

  The present invention relates to a conden-

high voltage generator.

  The usual high-voltage capacitors have heretofore been manufactured in the manner described hereinafter with reference to FIG. 1. First, capacitor elements A are superposed,

  alternation, electrode layers and dielectric layers

  of insulating paper or film of plastic material

  that, and winding of the laminated sheet obtained.

  A plurality of such capacitor elements are housed in a steel casing 4 and are connected to each other and to high voltage insulating terminals 7 by means of conductors 6. Finally, the elements are impregnated under vacuum with an oil. insulating 8

  for high voltage and they are sealed.

  In such high voltage capacitors,

  the dielectric layers must have a characteristic

  very low isolation cost because

  comes a lot in the life of the capacitor.

  In conventional high-voltage capacitors, it is important to

  the dielectric layers with an insulating oil

  for high voltage, in order to form insulating layers

  between the electrode layers. However, even with this arrangement, the capacitors are not

  completely free from insulation or elevation failures

abnormal temperature.

  If such an incident occurs, the temperature

  the capacitor itself amounts to an abnormal value

  male and the capacitor elements and the oil iso-

  lante expands under the effect of heat. This can lead to rupture or explosion of the steel casing and pollution of the environment by

  insulating oil projections. In addition, this can

  a fire, since an insulating oil is a combustible liquid with an included flash point

between 130 and 2000C.

  If a fire breaks out in a frequent

  such as high-rise buildings, underpasses, hospitals or schools, it is

  can be a lot of victims. Therefore

  Therefore, non-combustibility and explosion resistance characteristics are required for all electrical equipment. Oil-free devices have been realized for all electrical equipment at

  except for high voltage capacitors.

  In view of the above, the present Applicant has proposed, in Japanese Patent Application No. 59-3993, a high voltage capacitor

  comprising capacitor elements whose

  dielectric layers are arranged between the electrode layers and impregnated with synthetic resin, the

  capacitor elements being contained in a bowl-

  water-resistant synthetic resin molded housing, the housing being filled with gaseous sulfur hexafluoride (SF6) as insulation. Even with this capacitor, the gas pressure can increase and cause the explosion of the housing, if the protective device malfunctions so that the capacitor itself heats

up to an excessive value.

  The present invention relates to a high voltage capacitor which can be manufactured easily and is free of fire and explosion hazards.

  The invention also relates to a conden-

  high voltage generator which ensures a good dissipation

heat.

  According to the present invention, no gas or liquid is used as the insulating medium. To the

  instead, not only the dielectric layers are impregnated

  in the capacitor elements with a synthetic resin, to increase the value of the insulation, but the capacitor elements -are also insulated with a synthetic resin, in that their outer periphery is molded in synthetic resin. This provides high voltage capacitors that do not pose a fire hazard or

  explosion due to an insulation fault.

  In addition, according to the present invention,

  relaxation layers of elastic material are pre-

  seen at regular radial distances in each capacitor element, to avoid cracking

  dielectric layers and the detachment at the junction

  between the electrode layers and the dielectric layers. Finally, according to the invention, several passages for the air are formed in the insulating layer around the elements of the capacitor to dissipate the heat of each of the capacitor elements and prevent

  their temperature rise abnormally.

  In accordance with the present invention, without the use of oil or an insulating gaseous medium, high voltage capacitors of large size are obtained.

  quality, non-flammable and resistant to explosion.

  Other objects and advantages of this

  invention will appear in the light of the description

  hereinafter of its non-limiting embodiments

  shown in the accompanying drawings in the

  which: Figure 1 is a section of a high voltage capacitor, according to the prior art; Figure 2 is a section of a high voltage capacitor according to the present invention;

  Figure 3 is a horizontal sectional view of

  the X-X line of Figure 2; Figure 4 is a view of another embodiment, similar to Figure 3; Figures 5 to 8 are plan views of exemplary capacitor elements;

  FIG. 9 is a section of the dielectric layer

  cudgel; Figure 10 is a section of the element of

capacitor, not coiled; -

  Figure 11 is a sectional view of yet another embodiment similar to that of Figure 3, but having several passages for air; and FIG. 12 is a sectional view of an embodiment similar to that of FIG. 4, but

  with several passages for air.

  We now refer to the drawings.

  FIG. 9 illustrates a dielectric layer

  comprises an insulating material 2, porous and of high caliber

  impregnation capacity, for example a woven or non-woven fabric, on both sides of which is fixed a film 1 of synthetic resin, for example polyester or

  polypropylene. The capacitor elements A, illus-

  FIGS. 5 and 6 are prepared by super-

  position of the dielectric layers a and electrode layers b, alternately, as shown in FIG. 10, and winding of the laminated sheet

thus obtained.

  A plurality of con-

  the densifier A along a wiring 6 ', as shown in FIG. 2. The gaps C and the periphery B are filled with an electrically insulating material with a high impregnation capacity, for example a fiberglass strip, a glass fabric, a glass mat, fragmented glass, a non-woven fabric

  woven fabric or paper, so as to obtain a

  predetermined peripheral ration. The set of capacitor elements is then placed in a metal matrix, as shown in FIG. 2, and subjected to hot drying and drying under

  empty, then to an impregnation with a synthetic resin

  such as an epoxy resin under high vacuum. The

  porous part of the dielectric layers a and the material

  Insulating material is impregnated with the same resin at the same time. To obtain better impregnation, the temperature of the synthetic resin must be maintained at 1000 ° C. and its viscosity lowered to about 20 cp and the high vacuum must be maintained during

  more than three hours. This ensures dielectric layers

  has good isolation characteristics. In addition, the outer casing is molded of resin

  synthetic, in solidarity with the condensate elements

  tor. Although, in the preferred embodiment,

  the impregnation of the capacitor elements and the

  In addition, the capacitor elements are impregnated with the insulator layer around the capacitor elements, mounted in a metal mold, and an insulating layer formed around the capacitor elements. This process is

  advantageous in that synthetic resins can be

  different materials, in particular a resin having a very good impregnability and a low viscosity, for the capacitor elements, and a resin having a good mechanical strength and

  a high viscosity, for the insulating layer.

  In the preparation of a capacitor element A by superposition of the electrode layers b and the dielectric layers a, as shown in FIGS. 7 and 8, relaxation layers 9 of elastic material must be interposed at regular intervals. eg "Hycar" cork, cork sponge and chipboard. The layers located between the relaxation layers 9 are electrically connected

  in parallel to each other. The layers of relationship

  xation absorb the force of contraction during the dura-

  curing of the synthetic resin, which avoids

  cracking of the dielectric layers and the detachment

  at the junction between the electrode layer and the dielectric layer and thus prevents the degradation of

  isolation. The distance t between the layers of relationship

  For example, if the thickness T of the capacitor element is 50 mm, the distance t should be 10 to 20 mm for ease of work, the value of

the weaker the better.

  The embodiment of Figure 11 is

  similar to that of Figure 3, except that

  two passages for the square section air 10 are formed in the insulating layer around the capacitor elements in the axial direction. Similarly, the embodiment of FIG. 12 is identical to that of FIG. 4, except that several

  passages for the air 10 'of elliptical section are

  swam in the insulating layer, in the axial direction.

  Air passages may have any

desired.

  The passages for the air 10 o L10 'can

  be formed during the molding of the insulating layer.

  As shown in Fig. 11, the air passages may be formed such that a portion of the outer periphery of the capacitor elements is exposed to the air passages to cool them directly. Air can circulate in the passages by natural or forced ventilation. The passages for the air cool the elements of the capacitor,

which prolongs their life.

Claims (3)

1. Capacitor that understands   a plurality of capacitor elements (A) comprising   each of the electrode layers b and the dielectric layers alternately superposed and wound   capacitor elements (A) being   of a layer of an electrically insulating material   lant (B, C) impregnated with a synthetic resin, the dielectric layers being impregnated with a synthetic resin, characterized in that axial passages for air (10, 10 ') are formed in said insulating layer. 2. Capacitor according to the   claim 1, characterized in that the capacitor elements (A) each comprise a plurality of   relaxation layers (9) of elastic material,   at regular radial distances t each other. 3. Capacitor according to the   2C vendication 1, characterized in that the axial passages (10) for air are formed so that a part of the outer periphery of the elements of   capacitor (A) is exposed in the axial passages.