EP0769795A2 - High-voltage high-power fuse for an electrical connection line - Google Patents

Abstract

The high voltage (HV) high-power fused coupling provides a cable connection Ä23Ü between a transformer and switchgear. The unit has a cylindrical insulating tube Ä2Ü and this has a conductive outer layer Ä1Ü as well as an inner layer Ä18Ü to limit discharges. Within this is the fuse capsule Ä3Ü with contact caps Ä4,4'Ü having connecting bolts Ä5,5'Ü at each end. The capsule has a ceramic core Ä8Ü on which the fuse wire is wound Ä9Ü. Quartz sand Ä7Ü provides an arc extinguishing action.

Description

The invention relates to a high-voltage, high-performance (HH) fuse for an electrical connecting line, in particular a cable line between a transformer and a switchgear, with a fuse insert accommodated in an insulating sheath and with a connecting element and with a conductive cover that surrounds the insulating sheath on the outside, and with a layer within the insulating sheath to discharge partial discharges.

In local network stations of the energy supply companies, the transformer outlets are protected with HV fuses, which are mostly housed within the enclosure of the switchgear. This technique is complex because the security area is different from the rest Isolation room of the switchgear must be sealed gas-tight. In addition, the accessibility of the HV fuses is very limited and thermal problems are to be expected due to the encapsulation. Overheated HV HRC fuse can destroy the entire switchgear.

Switchgear versions are currently available on the market in which the HV fuses are housed in insulating tubes outside the remaining insulating gas space of the switchgear and connected to it by means of plugs. This version requires an additional, locked metal housing as contact protection, which may only be removed when the transformer switch is switched off. In addition to the considerable structural design, it is objectionable that partial discharges can go out on the very thin fuse links due to the small spacing between adjacent outer conductors, which far exceed the permissible value for the system and do not allow a statement on the insulation behavior of the system based on partial discharge measurements or distort. It is also to be expected that permanent discharges on the fusible conductors due to material removal and chemical reactions will lead to permanent changes in the characteristics and function.

From DE OS 40 14 392 a high-voltage high-performance (HH) fuse of the type mentioned is known, but in which two groups of fusible conductors are accommodated in two separate chamber housings and each chamber housing carries a high-resistance layer on the inside. This HV fuse is complex because of the two separate chambers. It also has the disadvantage that the switching behavior of the fuse can be influenced by the high-resistance layer, which is not further defined. Since the high-resistance layer lies directly in the switching space of the arc, extensive measures are necessary to rule out a negative influence on the otherwise known switching behavior of arcs in uncoated insulating tubes.

The object of the invention is therefore to design the HV fuse of the type mentioned in such a way that the switching behavior is improved, a particularly compact encapsulation of the HV fuse is possible, the radial dimensions of which do not exceed the standard cable sets of the same nominal voltage, and that partial discharges from the fusible conductor in particular can be limited to a permissible size by special control measures of the electrical field.

According to the invention, this object is achieved in that the insulating sheath is a one-piece, cylindrical insulating tube and at least one of the connection elements via one Connector connected to a cable with field control body. The known fuses also have insulating casings, which, however, disadvantageously consist of divided housings, with each disconnection point indicating an electrical weak point. If you allow radial air gaps, for example, you accept a much lower insulation resistance. This could only be remedied by increasing the total thickness of the insulation.

According to the invention, however, a one-piece insulating tube has been chosen, i.e. a one-piece, unbroken insulating tube. This avoids every electrical joint, every weak point and can still keep the thickness of the insulating materials smaller. If the insulating tube is cylindrical in accordance with the invention, the HV HRC fuse can be configured in a manner that complies with the cable, i.e. one achieves a compact design in such a way that the connection dimensions available for commercially available cable fittings - especially in the radial direction - are not exceeded. This also does not affect the electrical properties of the transformer loop.

If, furthermore, a field control body is connected to a connection element, internal partial discharges can also be suppressed. This is achieved according to the invention to such a degree that the product is considered to be "partially discharge-free" if the partial discharges are undershot. The yardstick for this can be, for example, the applicable standard for cable fittings with the same nominal voltage.

The design of the encapsulated HV fuse of the invention preferably corresponds to that of a cable sleeve or that of a pluggable or screwable cable connection according to DIN VDE 0278 part 6.

According to the invention, it is also advantageous if the insulating tube covers at least one connector and at least partially covers at least one field control body. Although field control bodies are commercially available, accommodating such a field control body in the insulating tube, which at least partially covers it, permits a particularly compact encapsulation with a design that conforms to the cable technology. This is favorable for space-saving accommodation on switchgear or the like.

Furthermore, it is advantageous according to the invention if, in order to limit partial discharges within the insulating tube, a field-controlling layer of semiconducting material is arranged on at least a portion of the length of the insulating tube and / or the fuse link with its external fuse tube. The field-controlling devices located inside the insulating tube have, for example, components made of electrically semiconducting Materials. Such devices are used in particular in connection with the cable fitting technology to shut off terminations and to shield connectors. The field-controlling layer of semiconducting material provides sufficient field shielding for the intact fuse element and also provides sufficient insulation between the contact caps located at the ends of the fuse insert during and after the fuse has been switched off.

In an advantageous development of the invention, at least one connector is shielded from a conductive electrode. The conductivity of an electrode considered here is in the range between 1 and 1000 Ωcm. This relatively high conductivity serves for the partial discharge-free electrical shielding of the connection point. When using this electrode shield, an additional field-controlling layer could only be arranged in the area of the fuse link, thus simplifying the overall structure of the HV fuse. These conductive electrodes can advantageously be installed in the insulating body, e.g. by pouring, gluing or the like. A similar gap-free and seamless shielding can also be achieved with a conductive lacquer coating or equivalent measures. According to the invention, it is also favorable if the field-controlling layer made of semiconducting material covers the entire safety tube and at least one connector. In this embodiment, the insulating tube can be manufactured more easily if the field-controlling layer is designed, for example, as a continuous tube. Alternatively, according to the invention, the field-controlling layer made of semiconducting material can also be attached to the safety tube; while in another other embodiment this layer can also be applied in the form of a glaze and / or in connection with a glaze on the porcelain safety tube. Then the porcelain manufacturer can already provide the safety tube with the glaze and deliver it, so that the remaining assembly at the manufacturer of the HV fuse is considerably simplified.

It is also conceivable and advantageous if, according to the invention, the field-controlling layer made of semiconducting material is applied as a hose over the safety tube and / or field control body. You can use a standard fuse and retrofit the hose. For example, it is expedient to design the semiconductor layer as a heat shrink tube or alternatively as an elastomer tube. Such hoses can not only be manufactured practically, but can also be handled, assembled and inserted in the securing structure at low cost.

Other favorable measures for the compact design also consist in selecting a field control body according to the invention, the outer diameter of which is approximately equal to that Outside diameter of the fuse link is. In this way, a cylindrical insulating tube can be easily manufactured and used without gradations. According to the invention, this or the above-mentioned field control body advantageously creates an adaptation to cables with different conductor cross-sections and diameters and thus brings about prerequisites for universal applicability and versatile use.

Field control devices consist of a mixture of electrically insulating and conductive components. The insulating components form the mechanical framework (binder) for the conductive components.

Conductive components can e.g. Carbon black, SiC and metal particles. They are incorporated in paints, casting resins or elastomers, whereby the electrical conductivity of the batch can be varied within wide limits via their concentration.

Conductive varnishes are particularly suitable for application to existing construction elements (e.g. on the safety tube). Components made of casting resins and elastomers, e.g. the field control electrode mentioned above, prefabricated and assembled separately. Semiconductor tubes with the required properties are, in addition to the heat shrink tubes mentioned, also mechanically pre-stressed elastomer tubes (cold shrink tubes).

The field-controlling layer provides adequate shielding of the fuse element during operation and ensures sufficient insulation across the switching path after the fuse has been switched off.

If the field-controlling layer is applied in the form of the heat shrink tubing, then in a preferred embodiment it expediently protrudes beyond the insulating tube and preferably also beyond the open end (s) of the insulating tube as far as the field control body or bodies. There the hose can be connected to an earth conductor.

In a further different embodiment, the tube can be shrunk on as a pre-tensioned elastomer tube, for example in the form of a cold-shrink tube made of silicone rubber. This hose can also protrude beyond the open end of the insulating tube (or beyond its two ends) to the field control body or bodies and there it can preferably be connected to an earth conductor. When using the field control hoses, if they extend in particular over the entire length of the fuse link, the connection points and, if present, the field control body, additional field control electrodes are not necessary over the connectors.

In a further advantageous embodiment of the invention, the insulating tube is open on at least one side for receiving a cable end with field control body and is provided on the other, non-open side with a plug connection for standardized device bushings. The invention therefore enables the plug part of the invention to be used uniformly for all connected cable cross sections and cable types, because the field control body ensures the corresponding adaptation, as mentioned above.

Instead of being used in the form of a fuse plug when one side is open, the insulating tube can alternatively be made open on both sides, so that the fuse acts as a locking sleeve. In another embodiment, device connections could also be provided on both sides of the insulating tube, so that the function of a safety bridge results.

It can also be advantageous if, according to the invention, the insulating tube in the region of the connector to the cable is additionally provided with a plug connection for standardized device bushings. As a result, the T-type design allows additional grounding of the cable. In other words, this embodiment allows a ground circuit.

Figur 1

die Querschnittsansicht einer Hochspannungs-Hochleistungs-(HH-) Sicherung als Winkelstecker im Schnitt und teilweise mit Ausbrechungen,

Figur 2

eine der Figur 1 ähnliche Ansicht, jedoch von einer zweiten Ausführungsform, bei welcher die innerhalb des Isolierrohrs angeordnete feldsteuernde Schicht auf dem in der Zeichnung unten angeordneten Feldsteuerkörper endet, und zwar nur etwa 2 cm vom verbinderseitigen Ende entfernt,

Figur 3

eine der Figur 1 ähnliche Ansicht, jedoch von einer dritten Ausführungsform, bei welcher der feldsteuernden Belag auf den Sicherungseinsatz beschränkt ist mit Überlappungen zu den Elektroden zum Feldsteuerkörper,

Figur 4

eine Querschnittsansicht entlang der Linie IV-IV der Figur 1 oder Figur 5,

Figur 5

die Schnittansicht durch eine HH-Sicherung in Form einer Sicherungsmuffe, bei welcher die Ausgestaltung der feldsteuernden Schicht innen ähnlich aufgebaut ist wie bei der ersten Ausführungsform nach Figur 1,

Figur 6

eine ähnliche Schnittdarstellung wie Figur 5, jedoch von einer anderen Ausführungsform mit einem Aufbau der feldsteuernden Schicht ähnlich wir in Figur 2, wobei nämlich die in Rede stehende Schicht etwa 2 cm vom verbinderseitigen Ende unten und oben entfernt endet, und

Figur 7

wiederum eine ähnliche Ansicht wie Figur 5, wobei jedoch ähnlich dem Innenaufbau der Figur 3 des feldsteuernden Belag auf den Sicherungseinsatz beschränkt ist mit Überlappungen zu den Elektroden zum Feldsteuerkörper oben und unten, wobei die Elektroden den Bereich der Verbinder überdecken.

Further advantages, features and possible uses of the present invention result from the following description of preferred exemplary embodiments in conjunction with the attached drawings. These show:

Figure 1

the cross-sectional view of a high-voltage high-performance (HV) fuse as an angled connector in section and partially with knockouts,

Figure 2

1 is a view similar to FIG. 1, but of a second embodiment in which the field-controlling layer arranged within the insulating tube ends on the field-control body arranged in the drawing below, and only about 2 cm from the connector-side end,

Figure 3

2 is a view similar to FIG. 1, but of a third embodiment in which the field-controlling covering is limited to the fuse link with overlaps to the electrodes to the field control body,

Figure 4

2 shows a cross-sectional view along the line IV-IV of FIG. 1 or FIG. 5,

Figure 5

2 shows the sectional view through a HV fuse in the form of a locking sleeve, in which the design of the field-controlling layer is constructed on the inside similarly to that in the first embodiment according to FIG. 1,

Figure 6

a sectional view similar to Figure 5, but of another embodiment with a structure of the field-controlling layer similar to that in Figure 2, namely namely the layer in question ends about 2 cm from the connector-side end below and above, and

Figure 7

again a view similar to FIG. 5, but similar to the inner structure of FIG. 3 of the field-controlling covering being limited to the fuse link with overlaps to the electrodes to the field control body above and below, the electrodes covering the area of the connectors.

The fuses of all embodiments have a one-piece, cylindrical insulating tube 2 as an insulating sheath under a metallic sheath 1 as the conductive cover. Arranged in the insulating tube 2 is a fuse insert, generally designated 3, which carries contact caps 4 and 4 'at both ends with connecting bolts 5, 5'. Radially from the outside inwards, the fuse link 3 has a fuse tube 6, quartz sand 7 as an extinguishing agent and a winding body 8 made of z. B. ceramic on which fuse element 9 are held taut.

The lower connecting pin 5, which, like the upper 5 ', can be welded, screwed or attached in a similar manner, is connected via a connector 10 to the bare conductor 11 of a cable 23 with field control body 12, for example by pinching or screwing.

In the embodiments of FIGS. 5-7 (securing sleeve), the upper connecting bolt 5 'is arranged almost in mirror image with respect to the securing insert 3 arranged in the middle, namely connected to a field control body 12' via a connector 10 '.

In contrast to this, the embodiments according to FIGS. 1-3 are constructed as angled plugs, the upper connecting bolts 5 'of which are provided with a bore (with or without thread) 13. A plug pin 14 can be inserted through this bore 13 and screwed tight. By means of plug socket 15 with outer cone 16 and sealing plug 16 ', the connection to the bushing designated as a whole 17 is created. This angled plug connection of FIGS. 1-3 can be screwed or plugged via the bushing 17 onto a transformer or switchgear (not shown). One such embodiment is a fuse in the form of a cable connector.

The insulating tube 2 covers the fuse link 3, covering all embodiments. including its contact caps 4, 4 'and connecting bolts 5, 5' and also covers most of the field body 12 or 12 '. In the angled connector according to FIGS. 1 to 3, the essentially cylindrical part of the insulating tube 2 is adjoined at the top by a T-piece 22, which is also insulating and covers the outer cone 16 and sealing plug 16 '. To limit partial discharges, a field-controlling layer 18 made of semiconducting material is arranged within the insulating tube 2. In the embodiment of FIGS. 1 and 5, this field-controlling layer 18 extends over the entire longitudinal direction of the insulating tube 2, ie from the field control body 12 shown below to the upper contact cap 4 '. In the embodiment of FIG. 2, this semiconducting, field-controlling layer 18 is shorter in the lower region, ie it ends on the field control body 12, but is about 2 cm away from the lower connector 10. The situation is similar in the embodiment according to FIG. 6, although the field-controlling layer 18 (dashed line) is shorter there both above and below in the sense of FIG. 2. Therefore, in the remaining area of FIGS. 2 and 6, a layer-free annular space 19 can be seen, namely in FIG. 2 below and in FIG. 6 both below and above.

In the embodiment according to FIGS. 3 and 7, the field-controlling layer 18 only extends over the fuse link 3. It ends overlapping at electrodes 21, 21 '. The lower electrode 21 has a tubular shape, while a short tubular part of the upper electrode 21 '(in the case of the angled connector) is followed by a conical part which ultimately has a similar T-shape in the angled piece or T-piece 22. The upper electrode 21 'in the case of the angled plug according to FIGS. 1 to 3 therefore deviates from the simple tubular shape of the lower electrode 21 in order to overlap the upper connecting bolt 5', the plug socket 15 and the outer cone 16 with sealing plugs 16 '. In FIG. 3, the layer-free annular space 19 can be seen in the lower area of the field control body 12, which is also located at the top in the sleeve embodiment according to FIG. 7, where it is called 19 '.

In all embodiments, the field-controlling layer 18 is located radially inside the insulating tube 2 and outside the fuse tube 6 of the fuse link 3.

With regard to the electrodes or field control electrodes, one can see in all of the embodiments their simple tubular shape in the area around the field control body 12 or partially overlapping them, unless the field-controlling layer 18 is attached there, as in FIGS. 1, 2, 5 and 6, where the No need for an electrode. The simple tubular electrode 21 is therefore located in the lower region near the field control body 12 in the embodiments of FIGS. 3 and 7; 7 also at the top, because the sleeve embodiment is constructed symmetrically and also has a field control body 12 'at the top.

1 to 3, the electrode 21 'described above with the somewhat more complicated shape is located in the upper region of the bushing 17.

The field control devices are insulating in the longitudinal direction and conduct (in the manner of a Faraday cage) in the radial direction, so that the partial discharge is deactivated.

It has already been stated above that the field-controlling layer 18 is preferably made from semiconducting material, e.g. B. as a layer on the fuse tube 6 of the fuse link 3. The manufacturer of the porcelain fuse tubes 6 could alternatively apply a glaze which has field-controlling properties. Alternatively, the field-controlling layer can also be covered as a hose over the securing tube 6, be it as a heat-shrinkable hose or as an elastomer hose. A field-controlling layer can also be applied to the inner surface of the insulating tube 2 by dipping or spraying, which would then also be provided in the assembly described here in the space between the insulating tube 2 and the parts arranged inside, such as the fuse link 3, connector 10 and field control body 12.

All figures show an insulating tube 2 open on the underside. There, the end of a cable 23 with the field control body 12 is received by the insulating tube 2.

In the embodiments according to FIGS. 5 to 7 (securing sleeve), the side of the insulating tube 2 shown above is also open, where the end of a cable 23 'is also received via the field control body 12'.

In the embodiments according to FIGS. 1 to 3, however, the upper end of the insulating tube 2 is not open but is provided with a bushing 17 as a plug connection for standardized device bushings.

Another possible embodiment is not shown, in which the insulating tube 2 in the area of the connector 10 is additionally provided radially outward with a plug connection for standardized device bushings. There you could ground the cable 23. The fuse could then also be used as a safety bridge.

The invention can also be expressed in such a way that a field-controlling layer 18 is arranged in the insulating tube 2 at least around the fuse link 3. Before assembly, ie after the connector 10 has been produced, the field-controlling layer 18 would then be in the Embodiment of Figure 1 applied according to the dashed line, ie starting from the cap 4 'down to around the field control body 12. Then the insulating tube 2 with the upper electrode 21 'could be put on. In the case of the embodiment in FIG. 3, the field-controlling layer 18 is in turn only applied to the fuse tube 6 of the fuse link 3, for example in the form of a prefabricated fuse link, after which the electrode 21 shown in FIG. 3 is to be applied, which overlaps the area of the connector 10 . This would practically have a T-plug with the tubular electrode 21 attached below the fuse link 3.

The electrode could also be regarded as an integral part of the field-controlling layer 18, so that the starting form according to FIGS. 3 and 7 would represent a first solution principle, according to which the field-controlling layer in any case extends over the fuse link 3; with the second embodiment according to FIGS. 2 and 6, in which the field-controlling layer also passes over the connectors 10 and 10 and 10 'from the area above the fuse link 3; as a third embodiment corresponding to FIGS. 1 and 5, in which the field-controlling layer 18 is drawn out from the upper cap 4 'to beyond the field control body 12 or in FIG. 5 is drawn from the lower field-controlling body 12 to the upper body 12' ; and a further fourth embodiment corresponding to FIGS. 3 and 7, where the field-controlling layer in the region of the connector or connectors 10, 10 'is designed as an electrode 21.

Claims (11)

High-voltage, high-performance (HV) fuse for an electrical connecting line (23, 23 '), in particular a cable line (23, 23') between a transformer and a switchgear, with a fuse link (3) which is covered in an insulating sheath (2) ) with connection element (5, 5 ') and with a conductive cover (1) surrounding the insulating sheath (2) and with a layer (18) inside the insulating sheath (2) to limit partial discharges, characterized in that the insulating Sheathing is a one-piece, cylindrical insulating tube (2) and at least one of the connection elements (5, 5 ') is connected to a field control body (12, 12') by means of a connector (10, 10 ') with a cable (23, 23'). High-voltage fuse according to claim 1, characterized in that the insulating tube (2) covers at least one connector (10, 10 ') and at least partially covers at least one field control body (12, 12'). HV fuse according to claim 1 or 2, characterized in that to limit partial discharges within the insulating tube (2) a field-controlling layer (18) made of semiconducting material on at least a portion of the length of the insulating tube (2) and / or the fuse link (3rd ) is arranged with its external safety tube (6). HR fuse according to one of Claims 1 to 3, characterized in that at least one connector (10, 13-16) is shielded by a conductive electrode (21). HV fuse according to one of Claims 1 to 4, characterized in that the field-controlling layer (18, 21) made of semiconducting material covers the entire securing tube (6) and at least one connector (10, 14-16) (Figures 1 and 2; 5 and 6). HV fuse according to claim 1 or 4, characterized in that the field-controlling layer (18) made of semiconducting material is applied to the securing tube (6). HR fuse according to one of Claims 1, 4 or 6, characterized in that the field-controlling layer (18) made of semiconducting material in the form of a glaze and / or in connection with a glaze is applied to the security tube (6) made of porcelain. HRC fuse according to one of Claims 1 to 4, characterized in that the field-controlling layer (18) made of semiconducting material is applied as a hose over the securing tube (6) and / or the field control body 12. HV fuse according to one of Claims 1 to 8, characterized in that the field-controlling layer (18) made of semiconducting material is applied to the inner surface of the insulating tube (2). HV HRC fuse according to one of Claims 1 to 9, characterized in that the insulating tube (2) is open on at least one side for receiving a cable end (23) with field control body (12) and on the other, non-open side with a plug connection ( 14-16) is provided for standardized device bushings (Figures 1-3). High-voltage fuse according to one of claims 1 to 10, characterized in that the insulating tube (2) in the region of the connector (10) to the cable (23) is additionally provided with a plug connection for standardized device bushings.

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