FR2509948A1 - ELECTRICAL CIRCUIT ASSEMBLY COMPRISING AT LEAST ONE ENROBE COMPONENT - Google Patents

Abstract

THE ELECTRICAL CIRCUIT ASSEMBLY INCLUDES AT LEAST ONE ELECTRICAL COMPONENT 10 INTENDED TO BE POWERED BY A HIGH ELECTRICAL VOLTAGE, THIS COMPONENT BEING WRAPPED IN A DIELECTRIC COVERING MATERIAL 11 AND PROVIDED WITH A METAL ENCLOSURE 13. THE CIRCUIT ASSEMBLY IS ALSO EQUIPPED WITH A DEFORMABLE INTERMEDIATE MATERIAL 15 PROVIDED BETWEEN THE DIELECTRIC COVERING MATERIAL 11 AND THE METAL ENCLOSURE 13, THE PROVISION BEING SUCH ALL THE SERVICE CONDITIONS TO WHICH IS NORMALLY SUBJECT TO THE CIRCUIT ASSEMBLY, THE INTERMEDIATE MATERIAL 15 REMAINS CONTIGUOUS WITH ADJACENT PORTIONS OF THE DIELECTRIC COATING MATERIAL AND REMAINS CONTIGUOUS WITH AT LEAST SOME OF THE ADJACENT PORTIONS OF THE METAL ENCLOSURE, AND WHERE IN SERVICE, NO ELECTRICAL SHOCK OCCURS WITHIN THE INSIDE OF THE ENCLOSURE. CIRCUIT SET. USE ESPECIALLY FOR PROTECTING AND INSULATING ELECTRICAL COMPONENTS SUBJECT TO VOLTAGES OVER 3000 VOLTS.

Description

The present invention relates to assemblies

  electric circuits, and in particular it relates to assemblies of the type each comprising a component

  to be powered under high voltage.

  greater than 3000 volts, this component being embedded in a solid dielectric coating compound such as a

silicone elastomer.

  In the operating conditions normally encountered with such an electrical circuit assembly, and when the component is simply embedded in a solid dielectric coating compound, a

  electric charge on the surface of the dielectric coating

  remote from the component, unless

  precautions are taken to eliminate this charge If the charge is not removed,

  discharges by corona or arc, which creates para-

  unwanted electrical sites by giving birth to

  electric fields, which are detrimental to

  the circuit assembly The discharges are also

  may damage the dielectric coating.

  It is known to ensure that this burden of

  face is drained outside the circuit assembly,

  to prevent landfills, by providing the

  embedded in a casing or metal casing also part of the circuit assembly, this casing being contiguous with the dielectric coating material and being connected to a member which is external to the circuit assembly and is maintained at a potential The use of such a metal casing is also advantageous because this casing protects the component of the electric fields, of any origin, coming from outside the circuit assembly, which it confers on the circuit assembly. the mechanical robustness, and that it facilitates the assembly of the circuit assembly over other organs However, the inevitable existence of differences between the expansion coefficients of the

  metal of the envelope and the dielectric coating material

  under the conditions of temperature variation normally encountered, may result in shrinkage of the shell with respect to adjacent

  dielectric coating material, from which follows the

  This effect can be reduced by resorting to a flexible envelope, but this solution may not be desirable if the envelope

  flexible does not give the circuit assembly a robust

  desired mechanical strength, or if the flexible envelope

  can not be used satisfactorily to facilitate

  liter the possibly imposed assembly of the set to

  circuit over other organs.

  For an electrical circuit assembly in which an electrical component forming part of it is to be powered by a high electrical voltage and

  wherein the component is coated in a compound of

  solid dielectric packing and provided with a metal shell

  It is intended to be connected to a member external to the circuit assembly and maintained at a zero potential, the metal casing being intended to enable the load

  electrical power appearing on the surface of the embedding

  electrical device remote from the component to be removed from the circuit assembly, the present invention aims to provide a novel and advantageous circuit arrangement with which the metal casing provides effective prevention of electric discharges in the circuits. voids or gaps within the circuit assembly under all normal service conditions, while the metal shell may be conformed

  in order to have any mechanical resistance

  than desired and may be arranged to be able to be used to mount the circuit assembly on other members,

if desired.

  According to the present invention, a circuit assembly

  electric cooker comprising at least one electrical component

  that intended to be supplied by a high electrical voltage and embedded in a dielectric coating compound, and a metal shell associated with the coated component,

  is also provided with deformable intermediate material

  woven between the dielectric coating material and the metal shell, the arrangement being such that under all normal service conditions of the circuit assembly the intermediate material remains contiguous to the adjacent portions of the dielectric coating material

  and remains contiguous to at least some of the adjoining portions

  metal casing, and that in service, no electric shocks occur in the voids

  existing within the circuit assembly.

  It is essential to ensure, by any of the possible arrangements that will be seen later or by any combination of them, that there can be no gaps at least at the interface between the material dielectric coating and the deformable intermediate material under all normally encountered service conditions, if such a result can not be obtained as an inherent feature

  to the arrangement of the electrical circuit assembly.

  It is also essential that the intermediate material is electrically conductive if there may be voids in the intermediate material or at the interface between the metal shell and the intermediate material, such voids being liable to form unintentionally under the conditions In these circumstances, it is necessary for the intermediate material to have sufficient electrical conductivity and to remain sufficiently in contact with the metal casing so that the electric charge which would otherwise appear on the surface of the dielectric coating eliminates at a speed or

  flow rate which makes it impossible to

  within the intermediate material or at the interface between the envelope and the intermediate material When the intermediate material is an elastically deformable cellular material or foam, it is essential that the electrical charge is removed at a flow rate of at least

  sufficient to ensure that it can not be

  discharges within the voids of the foam, in

  all conditions of service normally encountered.

  When the electrically conductive intermediate material

  deformable and plastic material, and regardless of whether it is also elastic or not, it can be made electrically conductive in there

  also adding a charge or electrical supply

  conductor of any suitable shape In general, electrically conductive material is

  driver to oppose the existence and / or training

  Unintentional voids within the circuit assembly under all normal service conditions and / or electrical conductivity sufficient to ensure that it can not occur.

  discharges within the circuit assembly.

  If the deformable intermediate material is not electrically conductive, it can be considered as part of the dielectric coating material, and the electric charge then appears on its surface located away from the coated component instead of appearing at the surface.

  surface of the main part of the dielectric coating

  that, if the arrangement is not such that this surface charge is removed by the metal shell However, it is essential that no vacuum is formed or can be formed accidentally or at the interface between the material intermediate and the metal shell nor

  within the intermediate material, under all conditions

  of service normally

seems to electrical circuit.

  The intermediate material, whether electrical

  conductive or not, and whether or not

  Foam shape, can be elastically deformable.

  With an elastically deformable intermediate material, the tendency to the appearance of voids is less

  greater than it would otherwise be at the interfaces of

  intermediate material with the dielectric coating and with

the metal envelope.

  Whatever the arrangement, the material

  deformable mediator may comprise at least one material

  plastic, such as polyurethane.

  Advantageously, the intermediate material

  deformable has a composition that allows it to

  to adhere, in some way, to the enor-

  In these conditions, irrespective of whether the deformable intermediate material is elastic or non-elastic, it may be possible to ensure that no

  voids in any of the interfaces to which the material adheres

  For example, when the intermediate material comprises at least one polyurethane and the dielectric coating material is a silicone elastomer, the intermediate material may have a rough surface, which allows it to adhere by anchoring.

  to the contiguous portions of the dielectric coating.

  The characteristics and advantages of the invention

  more fully from the detailed description of the

  which is given below as a nonlimited example.

  tative with reference to the accompanying drawing, which

  sectional balancing an embodiment of a set

  with an electric circuit according to the present invention.

  The electrical circuit assembly shown comprises a plurality of electrical components, generally designated by the reference numeral 10, and intended to be subjected to a high voltage power supply, not shown, which is for example 15 000 volts. The components 10 are embedded in a dielectric coating compound 11, formed for example by a silicone elastomer or a solid plastic resin Si, in the circuit assembly, the components 10

  are simply coated in the coating compound

  11, it appears in the conditions of service

  normally encountered an electrical charge to the over-

  face 12 of the dielectric coating located at a distance from the

  components Such a charge may cause discharges

  effected by arcing or arc, which give rise to unwanted electrical noise, by creating electric fields that interfere with the proper functioning of the circuit assembly In addition, such discharges are

  likely to damage the dielectric coating.

  It is known to provide the electrical circuit assembly comprising the component coated with a metal casing, as indicated at 13, this cell being for example made of aluminum. The metal casing 13 is connected to an element, generally designated by the reference numeral 14. which is external to the circuit assembly and is maintained at zero potential. Thus, if the metal casing 13 is contiguous with the dielectric coating material, the

  charge appearing on the surface of the dielectric coating

  that is eliminated, which removes the electric shocks. The implementation of such an envelope is

  also advantageous in that it protects the components

  electrical fields of any origin

  from the outside of the circuit assembly, which it imparts to the circuitry of the mechanical strength and facilitates mounting of the circuit assembly to other members. However, the unavoidable existence differences in the coefficients of dilation of the

  metal of the envelope and the dielectric coating material

  under the usual temperature variation conditions, can lead to a withdrawal of the dielectric coating material with respect to the envelope,

  accidentally giving rise to voids in the-

  which discharges can occur It is known to reduce this effect by using an envelope

  flexible, but this solution may not be desirable.

  ble if the flexible envelope does not confer on the whole

  the desired robustness, or if the flexible envelope

  ble can not be used satisfactorily to facilitate the possibly imposed assembly of

  circuit over other organs.

  According to the present invention, the conventional arrangement

  circuit set which was considered above

  is modified as shown in the drawing below.

  appended by the arrangement of an electrically conductive intermediate material and elastically deformable 15

  between the dielectric coating material 11 and the coating

dielectric loppe 13.

  The arrangement is such that it can not create voids at least at the interface between the dielectric coating material and the intermediate material

  deformable, under all usual service conditions.

  the electric circuit set This result can

  to be obtained as a characteristic of the

  electrical circuit assembly, or

  to any one or any combination of the possible provisions that will be considered below.

  The intermediate material elastically deforms

  mable comprises a cellular or foam material comprising

  both voids in which discharges can occur Thus, it is necessary that the cellular intermediate material has sufficient electrical conductivity and that it remains sufficiently in contact with the envelope

  metal to ensure that the load is dissipated

  In such a way as to prevent discharges from occurring, at least in these voids. An intermediate material comprising a plastic material such as the cellular material referred to above.

  can be made electrically conductive by incorpora-

  to it a charge or supply of electricity

  conductor of any appropriate shape, such as

carbon.

  The intermediate material 15 is sufficiently elastically deformable, and the arrangement of the circuit assembly is such that the intermediate material remains contiguous to both the dielectric coating and the envelope

  metal under all conditions of service

  which is normally subjected to the circuit assembly, without it remains or that it forms accidentally voids at the interfaces between the intermediate material on the one hand and the dielectric coating and the metal shell on the other hand, in which discharges could occur Usually, the arrangement is

  such that the intermediate material is deformed elastically

  under all the conditions of service encountered.

normally.

  Alternatively, the arrangement may be such that

  voids may be formed accidentally

  between the intermediate material and the metal casing, and it is imposed on the intermediate material to be of sufficient electrical conductivity and

  remain in sufficient contact with the metal envelope

  to prevent landfill

in such voids.

  An intermediate material comprising a plastic material such as a polyurethane

  is also advantageous because it pre-

  feels a rough surface, likely to allow him

  to adhere by anchoring to the contiguous portions of the enro-

  dielectric, for example, when the dielectric coating

  The tread comprises a silicone elastomer. It is desirable, but not essential, for the intermediate material to have a composition to allow it to adhere, in any way, to the dielectric coating material, and / or the metal shell, thereby providing an effect complementary to that of the elasticity of the intermediate material as to ensure that the intermediate material remains

  contiguous to adjacent portions of the dielectric coating

  that and remains contiguous to at least some of the adjacent portions of the metal shell, under all conditions normally

circuit.

  In general, the intermediate material is

  avoid the creation and / or accidental training

  such voids within the circuit assembly under all service conditions normally encountered, and / or to have sufficient electrical conductivity to ensure that no discharges occur

within the circuit assembly.

  The arrangement of the intermediate material inside the circuit assembly allows the metal casing to have any desired mechanical strength This mechanical strength is no longer at

  least partially restricted by the need for the

  to bend in order to lend itself satisfactorily

  the evacuation of electrical charges from the sur-

  dielectric coating material, under all service conditions normally

  In addition, the metal casing

  lique may have any form to facilitate the

  mounting the circuit assembly on other members.

  It is desirable, but not essential, that the metal shell form a complete enclosure for

  the coated components In this respect, the

  of an electrical circuit assembly in accordance with this

  invention, such that the electric charge which appears

  otherwise, on any portion of the surface of the enro-

  dielectric bage is evacuated under a flow guaranteeing

  that no landfill can occur.

  The arrangement may be such that the intermediate material does not completely surround the components

  coated, for example, if part of the metal shell

  It is flexible, and is thus suitable in contiguity with the dielectric coating material, and / or if part of the metal shell is not subject to

  to retract adjacent portions of the material of

  dielectric coupling to which it is contiguous, and / or if the arrangement is such that, under the conditions of incomplete overlap of the intermediate material present, the electrical charge tending to appear on the surface of the dielectric coating material is discharged under a flow rate to prevent discharges occurring in existing voids within the circuit assembly, such voids possibly being formed

accidentally.

  The arrangement may also be such that the material

  Intermediate material is not a cellular or foam material, but voids may remain within the circuit assembly, and / or voids may accidentally form under the service conditions normally associated with the circuit assembly. , the essential thing being that such voids are far from the interface between intermediate material and dielectric coating, from which follows that it is necessary that the intermediate material has sufficient electrical conductivity and that it remains sufficiently in contact with

  the metal casing to ensure that discharges

  ghes can not occur in these voids.

  If there is no formation of voids in the

  of the circuit assembly, the intermediate material may not be electrically conductive. Under these conditions, the intermediate material may be considered as part of the dielectric coating, and the

  electric charge then appears on the surface of this

  ci that is located away from the coated components, if the arrangement is not such that this surface charge is evacuated by the metal shell However, it is essential that no vacuum exists or can not be formed accidentally both at the interface between the intermediate material and the metal shell and within the

  intermediate material, in addition to the condition of non-existent

  absence or absence of accidental formation of voids at

  the interface between the intermediate material and the enro-

  dielectric under all operating conditions normally associated with the electric circuit assembly. In such conditions, the material

  intermediate may not be a foam.

  The intermediate material, whether or not electrically conductive, can be elastic without

  as much to understand a foam.

  Intermediate material may not be

  elastic, but it must be deformable.

  If the intermediate material has sufficient adhesion to the dielectric coating material and / or the metal shell, it may not have to be elastic, regardless of whether or not the intermediate material is electrically conductive.

  Whether elastic or not, the material used

  may not adhere to the coating material

  electrical and / or metal enclosure.

Claims (9)

  Electrical circuit assembly comprising at least one electrical component intended to be supplied by a high electrical voltage, said component being embedded in a dielectric coating material and being provided with a metal casing, characterized in that the circuit assembly is also provided with a material   deformable intermediate disposed between the   dielectric coating and the metal casing, the   so that under all operating conditions normally experienced by the circuit assembly, the intermediate material remains contiguous to adjacent portions of the dielectric coating material and remains contiguous with at least some of the adjacent portions of the metal shell , and that in service,   there are no electric shocks inside the in the circuit assembly.   Circuit arrangement according to Claim 1,   characterized in that the deformable intermediate material ble is electrically conductive.   Circuit arrangement according to Claim 2, characterized in that the intermediate material is a   elastically deformable cellular material.   4 circuit assembly according to any one   claims 2 or 3, characterized in that the material   intermediate deformable material comprises a plastic material   tick that is made electrically conductive by   adding thereto an electrically mentally.   5 circuit assembly according to claim 1, characterized in that the intermediate material is an insulator, and in that no vacuum is created or can be created at the interface between the intermediate material   and the metal envelope, nor within the material   under all the conditions of service to which   is normally subjected to the circuit assembly.   6 circuit assembly according to any one of   of the preceding claims, characterized in that the   intermediate material is elastically deformable.   Circuit arrangement according to any one of   of the preceding claims, characterized in that the   deformable intermediate material is a plastic material   tick. Circuit arrangement according to Claim 7,   characterized in that the plastic material is a polyurethane   réthane. 9 circuit assembly according to any one of   of the preceding claims, characterized in that the   deformable intermediate material has a composition   to enable it to adhere to the metal envelope.   lic. Circuit arrangement according to any one   of the preceding claims, characterized in that the   deformable intermediate material has a composition   to allow it to adhere to the enameling dielectric bage.   Circuit arrangement according to claim 1, characterized in that the intermediate material is anchored to the contiguous portions of the coating material. dielectric.   Circuit assembly according to any one of   of the preceding claims, characterized in that the   dielectric coating material comprises an elastomer of silicone.