Patent Description:
Documents <CIT>, <CIT> and <CIT> refer to rupture discs for transformers. <CIT> and <CIT> disclose oil-filled lead-through housings open to the transformer tank.

An object to be achieved is to provide a housing part that can resist the pressures resulting from electric arcs occurring therein.

This object is achieved, inter alia, by a housing part, by an electrical system and by an operating method as specified in the independent claims. Exemplary further developments constitute the subject matter of the dependent claims.

For example, the housing part is filled with transformer oil and is mechanically strengthened in such a way that a pressure rise due to an electric arc is absorbed and led into a greater component to that the pressure rise is deflected by the housing part, before the pressure rise can cause rupture or significant leakage of the housing part. Thus, damage to the housing part and also to surrounding equipment, for example, caused by fire due to rupture or leakage of the housing part, can be prevented.

In at least one embodiment, the housing part is configured to be connected to an electric component, like a transformer or a shunt reactor, and is configured to house an electric line.

Moreover, the housing part is configured to be filled with a liquid, wherein the housing part comprises an electrically conductive material. The housing part has an open mounting side to be connected to the electric component. Claim <NUM> specifies the parameters for the housing part, and claim <NUM> specifies the operating method.

For example, the housing part is a turret to be mounted on a transformer or shunt reactor. The liquid may be a transformer oil configured to provide more efficient cooling than air. The electrically conductive material may be at least one metal, for example steel, like stainless steel.

The open mounting side is, for example, a bottom side of a cylinder that forms the housing part. Accordingly, at the open mounting side the housing part comprises an aperture so that the mounting side is, for example, to at least <NUM>% or <NUM>% or <NUM>% free of any solid material. Remaining areas of the mounting side may be formed of a material to rest on the electric component on which the housing part is mounted.

The open mounting side may be of plain fashion so that the housing part can rest on an even surface of the electric component. Otherwise, the open mounting side may comprise a structuring to improve connectivity with the electric component. Such a structuring may be formed, for example, by an indentation, by an adaptor or by a fit ring.

The surface-to-volume ratio of the housing part is comparably large. Thus, the surface-to-volume ratio is at least <NUM>-<NUM> or at least <NUM>-<NUM> or at least <NUM>-<NUM>.

The surface-to-volume ratio is at most <NUM>-<NUM>. The surface of the housing part relevant to determine the surface-to-volume ratio may be an interior surface of the housing part excluding an area of the opening in the mounting side, or the relevant surface may also be an exterior surface of the housing part, again not taking into account the area of the opening in the mounting side.

For example, if the housing part has the shape of a hollow cylinder, the relevant surface is an area of a cylinder barrel plus an area of a top side of the cylinder, assuming that a bottom side of the cylinder is completely open; when the cylinder has a height H and a radius R, then in this case the relevant surface is 2πRH + πR<NUM>. In another example, the housing part has the shape of a cuboid with a height H and a width W and a length K, then the relevant surface is <NUM>(L+K) + KL, again assuming that a bottom side of the cuboid is completely open.

Further assuming that a wall thickness of the housing part is small compared with its diameter, it is noted that the exterior surface and the interior surface of the housing part are approximately the same. 'Small compare with' can mean that there is a at least a factor of <NUM> or <NUM> between the wall thickness and the diameter. If the housing part is not of round fashion, the diameter may be calculated as the square root of four times an area of the housing part in said plane divided by π.

By means of the aforementioned values and the values for the ratio of the volume and wall rupture pressure addressed below, on the one hand a sufficiently stable housing part can be achieved, while on the other hand mechanical load to the electric component as well as manufacturing costs can be kept comparably low and high manageability can be achieved. Accordingly, the surface-to-volume ratio is between <NUM>-<NUM> and <NUM>-<NUM> inclusive, and the ratio of the volume and the wall rupture pressure of the housing part depends on the shape of the housing part: for straight turrets this value is between <NUM><NUM>MPa-<NUM> and <NUM><NUM>Mpa-<NUM> inclusive, for external or side turrets this value is between <NUM><NUM>MPa-<NUM> and <NUM><NUM>MPa-<NUM> inclusive, and for cable boxes this value is between <NUM><NUM>MPa-<NUM> and <NUM><NUM>MPa-<NUM> inclusive, to ensure both sufficient mechanical strength and manageability.

The rupture pressure may be the interior pressure of the housing part at which the hull of the housing device begins to disintegrate and begins to fracture and crack. The rupture pressure can be calculated, for example, by means of a finite element method, FEM for short, or may also be measured.

Accordingly, the housing part may be a reinforced turret for electrical equipment.

A high-energy internal electric arc in an oil-filled turret can create an extreme sudden pressure rise because of the small volume of the turret, and rupture may be accompanied by large oil spill and fires. The housing part, for example, the oil-filled reinforced turret described herein is designed to resist this large pressure rise without rupture and significant oil leak. Turret design modifications are, for example, thicker turret shells of steel or stainless steel, flanges, and stronger bolt connections. Then, the pressure rise is transferred to the electric component, for example, the transformer main tank, which is configured to absorb energy injected by elastic-plastic deformation. It is noted that the internal tank pressure in the electric component is much lower because of its large volume. This safety feature could prevent turret rupture and fires.

In addition, this reinforced design solution is applicable to other oil-filled small compartments such as cable terminations, cable boxes and side turrets like chimneys. This design may also apply to an on-load tap charger cover, OLTC cover for short, and to connections to the transformer tank.

Transformer turrets in which there is a bushing end and/or a bushing shield, cable terminations and cable boxes are the second most cause of fires in the case of internal electric arcing. An arcing peak pressure rise in such a small oil volume could be up to <NUM> times higher in comparison to the same event located in the main transformer tank.

One might think that a pressure relief valve could be the solution, but several studies reveal that such valves are not effective because of their comparably slow reaction time and small diameter. Other alternatives would be to avoid transformer designs with oil-filled turrets, cable terminations and cable boxes, or to use a large opening pressure relief device at a top cover of the transformer. However, these alternatives may come with reduced breakdown voltage or with an increased danger of oil spills.

The housing part described herein is intended to resist a specific internal arc energy and the related pressure. Thicker turret shells and flanges can provide better mechanical resistance to withstand rupture. A bigger bolt size including higher tightening torque and thicker turret flanges can prevent potential oil leakage. All these design changes can be a result of calculations and of a nonlinear finite element analysis. Said specific internal arc energy is, for example, <NUM> MJ or <NUM> MJ.

Once the pressure is contained in the turret, it will be transferred to the transformer main tank. The tank is going to deform to absorb this extra arcing gas volume. Tank displacement and resistance may be ensured by nonlinear finite element analysis.

As an example, the following modifications on a <NUM> diameter straight turret are performed:.

The turret could also be equipped with a pressure relief valve. The shape of the valve can be straight, or can be of an elbow or chimney type. The same principle could also be applied to other oil-filled small compartments such cable terminations and cable boxes.

The housing part and the design principles described herein can be applied, for example, to.

According to at least one embodiment, the housing part is a turret configured to be added to a transformer or also to a shunt reactor as the electric device. Thus, the electric line may be a high-power line or a high-voltage line configured to be applied with a voltage of at least <NUM> kV or of at least <NUM> kV, for example.

Further, an electric system is provided. The electric system comprises a housing part as indicated in connection with at least one of the above-stated embodiments. Features of the electronic system are therefore also disclosed for the housing part and vice versa.

In at least one embodiment, the electric system comprises one or a plurality of the housing parts. By means of the at least one housing part, the electric system may be provided with one or with a plurality of electric power lines. The electric system also comprises an electric component like a transformer or a shunt reactor, having at least one component tank. The at least one housing part is mounted to the component tank by the open mounting side so that an interior of the component tank is connected with an interior of the at least one housing part at the corresponding open mounting side. A volume of the component tank exceeds the volume of the housing part by at least a factor of <NUM> or by at least a factor of <NUM> or by at least a factor of <NUM>.

According to at least one embodiment, the housing part comprises a top side opposite the open mounting side. For example, the top side comprises at least one aperture to feed through the at least one electric line that is housed by the housing part.

According to at least one embodiment, the housing part comprises a side wall. The side wall connects the top side and the open mounting side. The side wall may be of a one-piece fashion or of a multi-piece fashion. As an option, the top side is thicker than the side wall.

According to at least one embodiment, the side wall and/or the top face is of a metal having a modulus of elasticity of at least <NUM> GPa or of at least <NUM> GPa at room temperature.

For example, the top face and/or the side wall are made of steel or stainless steel.

According to at least one embodiment, a wall thickness of the side wall is at least <NUM> or at least <NUM> or at least <NUM>. As an option, the wall thickness is at most <NUM> or at most <NUM> or at most <NUM>.

According to at least one embodiment, the side wall is composed of at least two elements, for example, of two elements or of three elements. These elements may be of identical or different design.

According to at least one embodiment, the side wall elements are connected by means of intermediate flanges located along the side wall between the top side and the open mounting side. Hence, in the case of two elements, each one of the side wall elements can comprise one intermediate flange; in the case of three and more elements, the at least one middle part comprises two intermediate flanges, and the two end elements each comprise one intermediate flange.

According to at least one embodiment, the intermediate flanges mechanically strengthen the side wall. Thus, the intermediate flanges can be reinforcing rings that thicken the side wall in the respective locations. For example, at the intermediate flanges the wall thickness of the side wall is increased by at least a factor of <NUM> and/or by at most a factor of <NUM>, compared with remaining areas of the side wall that are free of any flanges or the like.

According to at least one embodiment, the electric line housed by the housing part is connected to a bushing of the electric component. By means of the bushing, the electric line may be electrically connected to a cable or electric line of the electric component, for example, to an interior power line.

According to at least one embodiment, the bushing and/or the interior power line of the electric component protrudes out of the component tank. The bushing and/or the interior power line may terminate within the housing part. Thus, the housing part may also house the bushing.

According to at least one embodiment, the bushing comprises a shield. By means of the shield, an end of the electric line fed through the housing part is clutched. Optionally, said end of the electric line and an end of the interior power line of the electric component are clutched and/or coupled and/or connected by means of the shield and/or by means of the bushing.

According to at least one embodiment, the intermediate flanges run, or at least one of the intermediate flanges runs, around the bushing, the shield and/or cable on an exterior face of the side wall. Hence, the intermediate flanges can provide mechanical strengthening at or near a location at which there is the highest probability of an electric arc occurring.

According to at least one embodiment, a diameter and/or a length of housing part is/are at least <NUM> or at least <NUM> or at least <NUM>. Optionally, said diameter and/or said length of housing part is/are at most <NUM> or at most <NUM> or at most <NUM>. The length may be determined along a direction perpendicular with the open mounting side. The diameter may be determined in a plane in parallel with the open mounting side.

According to at least one embodiment, a minimum distance between the side wall of the housing part and the electric line housed in the housing part and/or the component interior line and/or the bushing and/or the shield is at least <NUM> or at least <NUM> or at least <NUM>. Alternatively or additionally, said distance is at most <NUM> or <NUM> or <NUM>. For example, said distance is between <NUM> and <NUM> inclusive. Hence, a diameter of the housing part is comparably large in order to reduce an internal arc risk. This distance may completely be filled with the liquid, before the electric arc occurs.

According to at least one embodiment, the volume of the component tank is at least <NUM><NUM> or at least <NUM><NUM> or at least <NUM><NUM>. As an option, said volume is at most <NUM><NUM> or at most <NUM><NUM> or at most <NUM><NUM>. Said volume may be the entire volume enclosed by the component tank. Hence, the actual volume of the liquid that fills the component tank may be smaller. For example, the volume of the liquid in the component tank is at least <NUM><NUM> or at least <NUM><NUM> or at least <NUM><NUM> and/or is at most <NUM><NUM> or at most <NUM><NUM>.

According to at least one embodiment, the liquid that fills the housing part and also the component tank is transformer oil. The transformer oil may be a silicone-based oil or a mineral oil.

According to at least one embodiment, the housing part further comprises at least one bottom flange. The bottom flange, or the bottom flanges, can surround the open mounting side. Like the intermediate flanges, the bottom flange can be a thickened portion of the side wall at the very end of the side wall at the open mounting side. The housing part can be mounted to the component tank by means of the bottom flange.

According to at least one embodiment, the housing part further comprises at least one top flange. The top flange, or the top flanges, may be located on a side of the side wall remote from the open mounting side, that is at the side wall near the top side.

According to at least one embodiment, at least one cover of the housing part forms the top side. The cover or the covers and, hence, the top side can comprise at least one cover flange. The at least one cover is fastened to the side wall by means of the at least one top flange and the at least one cover flange. Like the intermediate flanges and the bottom flange, the top flange can be a thickened portion of the side wall, located at the very end of the side wall at the top side.

According to at least one embodiment, a ratio of a thickness of the intermediate flanges and the wall thickness of the side wall is at least <NUM> or is at least <NUM>. Alternatively or additionally, this ratio is at most <NUM> or at most <NUM>. Hence, to avoid leakage of the liquid at the intermediate flange, said flange is designed comparably strong. The same may apply to a ratio of a thickness of the top flange and the wall thickness of the side wall and/or to a ratio of a thickness of the cover flange and the wall thickness of the side wall and/or to a ratio of a thickness of the bottom flange and the wall thickness of the side wall.

According to at least one embodiment, the cover comprises at least one lead-through opening, the electric line is fed into the housing part through the lead-through opening. Hence, the lead-through opening in the cover corresponds to the aperture of the top side.

According to at least one embodiment, at least one of the intermediate flanges, of the bottom flange and the component tank, and of the top flange and the cover flange are flanged together with a tightening torque of at least <NUM> kNm or at least <NUM> kNm or at least <NUM> kNm. As an option, the tightening torque is at most <NUM> kNm or at most <NUM> kNm. Hence, bolts that connect the respective flanges are torqued with a comparably high moment of force.

Further, an operating method for an electric system is provided. The electric system is designed as indicated in connection with at least one of the above-stated embodiments. Features of the electronic system and of the housing part are therefore also disclosed for the operating method and vice versa.

In at least one embodiment, the operating method for the electric system comprises:.

Hence, oil spill and resulting fires can be prevented.

According to at least one embodiment of the method, a travelling time of the pressure rise from a location of the electric arc to the open mounting side within the housing part is smaller than a full build-up time of the pressure rise and/or of the electric arc. For example, the maximum pressure and/or volume expansion and/or the full electric arc is established after at least <NUM> or after at least <NUM> of the beginning of the electric arc. However, the travelling time that the pressure rise needs in the liquid to reach the open mounting side is at most <NUM> or at most <NUM>. Hence, the pressure rise is released in part to the larger component tank before the pressure rise can fully deploy its destructive effect in the housing part having the comparably small volume.

According to at least one embodiment of the method, the electric arc occurs at or near the bushing and/or the shield. For example, a distance between a current carrying part fed through the housing part and the side wall of the housing part is smallest near the bushing and/or the shield.

A housing part, an electric system and an operating method described herein are explained in greater detail below by way of exemplary embodiments with reference to the drawings. Elements which are the same in the individual figures are indicated with the same reference numerals. The relationships between the elements are not shown to scale, however, but rather individual elements may be shown exaggeratedly large to assist in understanding.

<FIG> illustrate an exemplary embodiment of an electric system <NUM> comprising an exemplary embodiment of a housing part <NUM>. The electric system <NUM> also comprises an electric component <NUM> that is, for example, a transformer <NUM> or, as an alternative, a shunt reactor. An electric line <NUM> is provided to the electric device <NUM> through the housing part <NUM>. Hence, the housing part <NUM> may be a top turret <NUM> mounted on the electric component <NUM>.

The electric component <NUM> comprises a component tank <NUM> in which a base element <NUM> is located, see <FIG>. The component base element <NUM> includes, for example, transformer windings and a transformer core. Further, the electric component <NUM> comprises an interior line <NUM> by means of which current is fed to the component base element <NUM>. For example, the component interior line <NUM> is a high-power line and is configured to carry high voltages. The component tank <NUM> as well as the housing part <NUM> are filled with a liquid <NUM>, for example, a transformer oil.

As can be seen from <FIG> and <FIG>, the electric line <NUM> is connected to the component interior line <NUM> by means of a bushing <NUM>, for example. At an end <NUM> of the electric line <NUM>, optionally there is a shield <NUM> of the bushing <NUM> that clamps the electric line <NUM>. Said shield <NUM> may be located in the middle or approximately in the middle of the housing part <NUM>, seen along a direction perpendicular to an open mounting <NUM> side of the housing part <NUM>. For example, the electric line <NUM> comprises an electrically conductive core <NUM> and an electric insulation <NUM> around the core <NUM> that runs up to the end <NUM>.

In the region of the end <NUM>, see <FIG>, a distance between the bushing <NUM> of the shield <NUM> that are configured to carry current on the one hand, and the electrically conductive housing part <NUM> on the other hand, is comparably small. Thus, in this region there is the highest probability that an electric arc <NUM> may occur. Hence, the electric arc <NUM> may occur in a comparably narrow area of the housing part <NUM> and also within a relatively small volume defined by the housing part <NUM>.

Because of the electric arc <NUM>, the liquid <NUM> decomposes in the region of the arc <NUM> and a rapid pressure rise <NUM> occurs in the small volume in the housing part <NUM>, compare also <FIG> below. By means of the mechanically comparably strong housing part <NUM>, the pressure rise <NUM> is deflected into a by far larger volume of the component tank <NUM>. Hence, the pressure rise <NUM> can be absorbed in the component tank <NUM> and harm to the electric system <NUM>, for example, due to fires resulting from a spill of the liquid <NUM> and of gases out of the housing part <NUM>, can be prevented.

Accordingly, see <FIG>, the housing part <NUM> is constructed in a mechanically stable manner. However, attention has to be paid to ensure that the housing part <NUM> is not oversized concerning its mechanical properties in order to avoid too much mechanical load to the component tank <NUM> and in order to keep costs relatively low.

In this exemplary embodiment, the housing part <NUM> has, in principle, the shape of a hollow cylinder. A mounting side <NUM> of the housing part <NUM> facing the component tank <NUM> is essentially open, so that a diameter of an opening at the mounting side <NUM> corresponds to an inner diameter of the hollow cylinder. Hence, the opening at the mounting side <NUM> is as large as possible.

A top side <NUM> of the housing part <NUM> may be formed of a cover <NUM>. As an option, atop the cover <NUM> there is a further element of the housing part <NUM> in order to mount the electric line <NUM>. Thus, by means of the further element a lead-through opening <NUM> is defined at the top side <NUM>.

The top side <NUM> and the open mounting side <NUM> are connected by a side wall <NUM>. As an option, the side wall <NUM> is of multi-piece design so that the side wall <NUM> is composed of two elements <NUM>. The elements <NUM> can be of the same design or can have different shapes. For example, the elements <NUM> of the side wall <NUM> are tubes having flanges <NUM>, <NUM>, <NUM> at their respective ends.

Thus, at the open mounting side <NUM> there is a bottom flange <NUM>, at an interface between the elements <NUM> of the side wall <NUM> there are two intermediate flanges <NUM>, and at the top side <NUM> there is a top flange <NUM> of the topmost element <NUM> of the side wall <NUM> and a cover flange <NUM> of the cover <NUM>. All the flanges <NUM>, <NUM>, <NUM>, <NUM> can be formed integrally with the respective elements <NUM>, <NUM> and may constitute rings or rims at the end of the tubes that form the elements <NUM> of the side wall <NUM>. The flanges <NUM>, <NUM>, <NUM>, <NUM> may be connected by means of bolts <NUM> and by means of an O-ring <NUM> between each one of the elements <NUM>, the cover <NUM> and the component tank <NUM>. The O-rings <NUM> may be of a rubber or also of a metal.

As an option, the intermediate flanges <NUM> are located close to the end <NUM> of the electric line <NUM> and, thus, near the shield <NUM> of the bushing <NUM>. Hence, the intermediate flanges <NUM> may serve as a mechanical strengthening of the side wall <NUM>. Moreover, the probable electric arc position is relatively close to the open mounting side <NUM> so that the pressure rise <NUM> can be led into the larger component tank <NUM> within a short period of time.

The liquid <NUM> may fill, for example, <NUM>% to <NUM>% of a total internal volume of the housing part <NUM>, the remaining space within the housing part <NUM> is occupied by the electric line <NUM>, the bushing <NUM> and the component interior line <NUM>. The same may apply to the component tank <NUM> relative to the component interior line <NUM> and the component base element <NUM>.

Optionally, the following parameters apply to the housing part <NUM>, individually or in any combination, for example, with a tolerance in each case of at most a factor of <NUM> or at most a factor of <NUM> or at most a factor of <NUM>:.

Thus, the housing part <NUM> may have a surface-to-volume ratio of about <NUM>-<NUM>, and a ratio of the volume and a wall rupture pressure r of the housing part <NUM> may be about <NUM><NUM>MPa-<NUM>.

As an option, a valve <NUM> may also be present, for example, at the side wall <NUM> of the housing part <NUM>. However, such a pressure relief valve <NUM> is typically too slow to allow the pressure rise <NUM> caused by the electric arc <NUM> to be relieved in time.

In <FIG>, another exemplary embodiment of the system <NUM> is shown. The electric component <NUM> is, for example, a shunt reactor <NUM>, but may also be a transformer <NUM>, not shown.

There is a plurality of the housing parts <NUM> at a top side of the component tank <NUM>. For example, there are three top turrets <NUM>, each equipped with one electric line <NUM>. Further, additionally or alternatively to the top turrets <NUM>, there can be a cable box <NUM> as further housing part <NUM>.

Otherwise, the same applies for <FIG> as for <FIG>.

In <FIG>, an exemplary embodiment of the housing part <NUM> that is configured as a cable box <NUM> is illustrated. The cable box <NUM> may be of cuboid or of approximately cuboid shape, and may have an open mounting side <NUM> and a closed top side <NUM> as well as a closed side wall <NUM>. Optionally, there are multiple electric insulations <NUM> and electric lines <NUM> within the cable box <NUM>. For example, a surface-to-volume ratio of the cable box <NUM> is <NUM>-<NUM>, and a ratio of the volume and a wall rupture pressure r of the cable box <NUM> is <NUM><NUM>MPa-<NUM>. Therefore, this exemplary cable box is not part of the claimed invention.

Such a cable box <NUM> can be present in all the exemplary embodiments of the electric system <NUM>.

<FIG> schematically illustrate further exemplary embodiments of the electric system <NUM> comprising exemplary housing parts <NUM>.

According to <FIG>, the housing part <NUM> is configured as a side turret <NUM> located at a side wall of the component tank <NUM>. Such a side turret <NUM> can be present in all the exemplary embodiments of the electric system <NUM>, for example, additionally or alternatively to the top turret <NUM>. Otherwise, the same applies for <FIG> as for <FIG>.

According to <FIG>, the housing part <NUM> is configured as a cable termination <NUM>. For example, the cable termination <NUM> is located within the component tank <NUM>, but could alternatively also be located at a side wall or at a top of the component tank <NUM>. Such a cable termination <NUM> can be present in all the exemplary embodiments of the electric system <NUM>. Otherwise, the same applies for <FIG> as for <FIG>.

According to <FIG>, the housing part <NUM> is configured as an on-load tap charger <NUM>. For example, the on-load tap charger <NUM> is located at a top of the component tank <NUM>. Such an on-load tap charger <NUM> can be present in all the exemplary embodiments of the electric system <NUM>. Otherwise, the same applies for <FIG> as for <FIG>.

As in all other exemplary embodiments, the top side <NUM> and the side wall <NUM> may merge to be a single surface of the housing part. Optionally, as shown in <FIG>, the top side <NUM> and the side wall <NUM> may be fashioned together as a dome, for example, as a hollow hemisphere.

In <FIG>, an exemplary pressure rise <NUM> is characterized. As illustrated in <FIG>, the pressure rise <NUM> and the associated electric arc may build up on a time scale of about <NUM>. Hence, in a closed fixed volume a maximum pressure would occur not before <NUM> after the electric arc has initiated. In other words, in the volume of the turret alone, with no tank attached, the maximum pressure in the turret would occur after <NUM>; however, this duration will also depend on the actual arcing duration.

As can be seen from <FIG>, a pressure P in the housing part <NUM> quickly rises and reaches a maximum on a time scale of <NUM> to <NUM>, and then declines. This comparably rapid decline is caused by the pressure release through the open mounting side <NUM> into the component tank <NUM>.

The pressure rises <NUM> in <FIG> are caused by electric arcs having an energy of <NUM> MJ and <NUM> MJ, respectively. Such fast rising high-energy electric arcs exceeding energies of, for example, <NUM> MJ can otherwise be very destructive in high-voltage applications.

Based on the turret <NUM> of <FIG>, the housing part <NUM> has a wall rupture pressure r of <NUM> MPa. However, a leakage pressure l, at which minor and short-term leakage of the liquid <NUM> may occur in a region of the flanges <NUM>, <NUM>, <NUM>, <NUM> in case of high-energetic electric arcs of more than <NUM> MJ, is lower and amounts to <NUM> MPa.

Hence, the housing part <NUM> in the electric system <NUM> described herein can withstand high-energetic electric arcs.

The invention described here is not restricted by the description given with reference to the exemplary embodiments. Rather, the invention encompasses any novel feature and any combination of features, including in particular any combination of features in the claims, even if this feature or this combination is not itself explicitly indicated in the claims or exemplary embodiments.

Claim 1:
A housing part (<NUM>),
configured to be connected to an electric component (<NUM>),
configured to house an electric line (<NUM>), and
configured to be filled with a liquid (<NUM>),
wherein the housing part (<NUM>) comprises an electrically conductive material,
wherein the housing part (<NUM>) has an open mounting side (<NUM>) to be connected to the electric component (<NUM>),
wherein a surface-to-volume ratio of the housing part (<NUM>) is at least <NUM>-<NUM> and is at most <NUM>-<NUM>, characterised in that a ratio of the volume and a wall rupture pressure (r) of the housing part (<NUM>) is either one
- between <NUM><NUM>MPa-<NUM> and <NUM><NUM>Mpa-<NUM> inclusive if the housing part (<NUM>) is a straight turret,
- between <NUM><NUM>MPa-<NUM> and <NUM><NUM>MPa-<NUM> inclusive if the housing part (<NUM>) is an external or a side turret,
- between <NUM><NUM>MPa-<NUM> and <NUM><NUM>MPa-<NUM> inclusive if the housing part (<NUM>) is a cable box.