CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of Chinese Patent Application No.CN201510534309.3 filed on August 27, 2015 in the State Intellectual Property Office of China, the whole disclosure of which is incorporated herein by reference. BACKGROUND OF THE INVENTION

Field of the Invention

Embodiments of the present invention relates to an insulation termination assembly, more particularly, relates to an insulation termination assembly for a current carrying conductor from a circuit breaker or a transformer.

Description of the Related Art In a high-voltage or ultra high voltage cable connection system with a voltage level of

66KV or more, in order to realize a reliable electrical connection between a high voltage cable and an overhead line, it is required to install an insulation terminal assembly on a joint of the cable to form a cable accessory. In the prior art, the insulation termination assembly generally comprises an insulation tube, an insulation umbrella skirt, a metal flange and a conductive rod led out of an end of the insulation tube. Insulation oil is filled in the insulation tube. The cable is partly peeled at a connection end thereof, to form a cable joint. The cable joint is received in the insulation tube. The insulation umbrella skirt is formed on an outer wall of the insulation tube. The metal flange is attached to a base of the insulation base.

In the prior art, a plurality of support insulators are pre-installed on the metal flange.

Thereby, it increases the size of the metal flange, complicates the structure of the whole insulation termination assembly, and increases the cost of the metal flange and the insulation termination assembly. SUMMARY OF THE INVENTION

The present invention has been made to overcome or alleviate at least one aspect of the above mentioned disadvantages.

According to an object of the present invention, there is provided an insulation termination assembly comprising a tail assembly to simplify the structure of the insulation termination assembly and decrease the cost thereof.

According to an aspect of the present invention, there is provided an insulation termination assembly, comprising: an insulation tube having an inlet end and an outlet end opposite to the inlet end; an annular bottom plate mounted at the inlet end of the insulation tube; and a tail assembly The tail assembly comprises an insulation connection tube mounted on the annular bottom plate, and a shield tail tube communicated with the insulation connection tube. An inner space of the insulation tube is filled with insulation liquid, a joint of a cable is introduced into the inner space of the insulation tube from the inlet end of the insulation tube after passing through the shield tail tube and the insulation connection tube.

According to an exemplary embodiment of the present invention, the insulation connection tube comprises of: an inner tube; an outer tube provided outside the inner tube; and a connection part connected between the inner tube and the outer tube at ends of the inner tube and the outer tube. An installation end of the shield tail tube passes through a gap between the inner tube and the outer tube and is connected to the connection part.

According to another exemplary embodiment of the present invention, a first installation flange radially protruding outward is provided on the installation end of the shield tail tube, the shield tail tube is mounted to the connection part by use of a plurality of first connection pieces passing through a plurality installation holes in the first installation flange, respectively.

According to another exemplary embodiment of the present invention, a first seal pad is provided between the installation end and the connection part.

According to another exemplary embodiment of the present invention, the connection part radially protrudes outward beyond the outer tube, so as to form a second installation flange, and the second installation flange is mounted on the annular bottom plate.

According to another exemplary embodiment of the present invention, a second seal pad is provided between the second installation flange and the annular bottom plate.

According to another exemplary embodiment of the present invention, the shield tail tube is provided with a connection part which is used for connecting a grounding wire.

According to another exemplary embodiment of the present invention, the insulation termination assembly further comprises a connection base mounted at the inlet end of the insulation tube, and the annular bottom plate is mounted on the bottom of the connection base.

According to another exemplary embodiment of the present invention, the connection base comprises a third installation flange and an auxiliary insulation tube which are formed into a single piece, the auxiliary insulation tube is connected to the inlet end of the insulation tube, and the annular bottom plate is mounted on the third installation flange. According to another exemplary embodiment of the present invention, the connection base further comprises a plurality of insulation reinforcing ribs integrally formed with the third installation flange and the auxiliary insulation tube. The plurality of insulation reinforcing ribs each is connected to a surface of the third installation flange and an outer wall of the auxiliary insulation tube, so as to increase the connection strength between the third installation flange and the auxiliary insulation tube.

According to another exemplary embodiment of the present invention, the auxiliary insulation tube comprises: a first tube portion located at one end of the auxiliary insulation tube adjacent to the third installation flange; a second tube portion located at the other end of the auxiliary insulation tube far away from the third installation flange; and a third tube portion located between the first tube portion and the second tube portion. The first tube portion has a constant first outer diameter, the second tube portion has a constant second outer diameter less than the first outer diameter, and the third tube portion has third outer diameters gradually decreasing from the first outer diameter to the second outer diameter.

According to another exemplary embodiment of the present invention, an inner diameter of the insulation tube is slightly larger than the outer diameter of the second tube portion of the auxiliary insulation tube and less than the outer diameter of the first tube portion of the auxiliary insulation tube; the inlet end of the insulation tube is sleeved and connected to the outer wall of the second tube portion of the auxiliary insulation tube.

According to another exemplary embodiment of the present invention, the connection base and the insulation tube are made of the same insulation material.

According to another exemplary embodiment of the present invention, the joint of the cable comprises a conductor core, an inner insulation layer covered on the conductor core, a conductive shielding layer covered on the inner insulation layer, and an outer sheath layer covered on the conductive shielding layer, the insulation termination assembly further comprises of: a support seat mounted on a side of the annular bottom plate opposite to the tail assembly and extending into the inner space of the insulation tube; and a stress control cone mounted on the support seat. The stress control cone is sheathed at least on a cut end of the conductive shielding layer and a location of the inner insulation layer adjacent to the cut end of the conductive shielding layer.

According to another exemplary embodiment of the present invention, the insulation termination assembly further comprises a conductive output bar. The conductive output bar comprises: a first end extending out of the insulation tube; and a second end inserted into the insulation tube and connected to the first end. The second end of the conductive output bar is provided with a slot, the conductor core of the cable is adapted to be inserted into and engaged to the slot.

According to another exemplary embodiment of the present invention, the insulation termination assembly further comprises a high voltage shielding ring detachably mounted on the outer wall of the outlet end of the insulation tube and surrounding the first end of the conductive output bar.

According to another exemplary embodiment of the present invention, the insulation tube is a winding tube formed by winding glass fiber impregnated with epoxy resin.

In the above various exemplary embodiments of the present invention, the cable entering into the insulation tube is electrically shielded by the shield tail tube, and the shield tail tube is electrically isolated from the annular bottom plate made of metal by means of the insulation connection tube. In this way, the tail assembly is acted as a support insulator, which may reduce the size of the annular bottom plate used for mounting the tail assembly, simplify the structure of the insulation termination assembly, and decrease the cost. Furthermore, the assemble of the insulating connection tube and the shield tail tube may be completed in factory, and on field it only needs to connect the insulation connection tube to the annular bottom plate by bolts. Thereby, it simplifies the installation of the insulation termination assembly on field.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other features of the present invention will become more apparent by describing in detail exemplary embodiments thereof with reference to the accompanying drawings, in which:

Fig. l is a local longitudinal cross section view of an insulation termination assembly according to an exemplary embodiment of the present invention;

Fig.2 is a longitudinal cross section view of the insulation termination assembly of

Fig. l;

Fig.3 is an illustrative enlarged view of a portion indicated by A of Fig.2;

Fig.4 is an illustrative enlarged view of a portion indicated by B of Fig.2;

Fig.5 is a local longitudinal cross section view of a tail assembly of an insulation termination assembly according to an exemplary embodiment of the present invention;

Fig.6 is an illustrative exploded view of the tail assembly of Fig.5;

Fig.7 is an illustrative perspective view of a connection base, according to another exemplary embodiment of the present invention, for the insulation termination assembly of Fig. l; and

Fig.8 is a longitudinal cross section view of a cable joint at an end of a cable according to an exemplary embodiment of the present invention. DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE IVENTION

Exemplary embodiments of the present disclosure will be described hereinafter in detail with reference to the attached drawings, wherein the like reference numerals refer to the like elements. The present disclosure may, however, be embodied in many different forms and should not be construed as being limited to the embodiment set forth herein; rather, these embodiments are provided so that the present disclosure will be thorough and complete, and will fully convey the concept of the disclosure to those skilled in the art.

In the following detailed description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the disclosed

embodiments. It will be apparent, however, that one or more embodiments may be practiced without these specific details. In other instances, well-known structures and devices are schematically shown in order to simplify the drawing.

According to a general concept of the present invention, there is provided an insulation termination assembly, comprising: an insulation tube having an inlet end and an outlet end opposite to the inlet end; an annular bottom plate mounted at the inlet end of the insulation tube; and a tail assembly. The tail assembly comprises an insulation connection tube mounted on the annular bottom plate, and a shield tail tube communicated with the insulation connection tube. An inner space of the insulation tube is filled with insulation liquid, a joint of a cable is introduced into the inner space of the insulation tube from the inlet end of the insulation tube after passing through the shield tail tube and the insulation connection tube.

Fig. l is a local longitudinal cross section view of an insulation termination assembly 100 according to an exemplary embodiment of the present invention; Fig.2 is a longitudinal cross section view of the insulation termination assembly 100 of Fig.l.

In an embodiment of the present invention, as shown in Figs.1-2, the insulation termination assembly 100 may be used to electrically connect a high voltage or ultra high voltage cable 200, for example, with a voltage level of 66KV or more, to another high voltage cable or an overhead line.

As shown in Figs.1-2, in an embodiment of the present invention, the insulation termination assembly 100 mainly comprises an insulation tube 1, an annular bottom plate 2 mounted at the inlet end of the insulation tube 1, and a tail assembly 3. More specifically, the insulation tube 1 has an inlet end (right end in Figs.1-2) and an outlet end (left end in Figs.1-2) opposite to the inlet end. A plurality of insulation umbrella skirts 11 are formed on an outer wall of the insulation tube 1. An inner space 12 of the insulation tube 1 is filled with insulation liquid, for example, insulation oil. A joint of the cable 200 is introduced into the inner space 12 of the insulation tube 1 from the inlet end of the insulation tube 1.

Fig.5 is a local longitudinal cross section view of a tail assembly 3 of an insulation termination assembly 100 according to an exemplary embodiment of the present invention; Fig.6 is an illustrative exploded view of the tail assembly 3 of Fig.5.

As shown in Figs.1-6, the tail assembly 3 comprises an insulation connection tube 31 mounted on the annular bottom plate 2, and a shield tail tube 32 communicated with the insulation connection tube 31. The joint of the cable 200 extending out of an electrical apparatus (not shown) is introduced into the inner space 12 of the insulation tube 1 from the inlet end of the insulation tube 1 after passing through the shield tail tube 32 and the insulation connection tube 31.

In the insulation termination assembly 100 according to embodiments of the present invention, the cable 200 introduced into the insulation tube 1 is electrically shielded by the shield tail tube 32, and the shield tail tube 32 is electrically isolated from the annular bottom plate 2 made of metal by means of the insulation connection tube 31. In this way, the single tail assembly 3 is served as a support insulator, which may simplify the structure of the insulation terminal assembly and reduce the cost of it.

As shown in Figs.5 and 6, the insulation connection tube 31 comprises an inner tube 311, an outer tube 312 provided outside the inner tube 311, and a connection part 313 connected between the inner tube 311 and the outer tube 312 at ends of the inner tube 311 and the outer tube 312. An installation end 323 (upper end in Fig.6) of the shield tail tube 32 passes through a gap between the inner tube 311 and the outer tube 312 and is connected to the connection part 313. In this way, a portion of the shield tail tube 32 is sandwiched between the inner tube 311 and the outer tube 312, improving the insulation effect for the shield tail tube 32.

In an exemplary embodiment, a first installation flange 321 radially protruding outward is provided on the installation end 323 of the shield tail tube 32. The shield tail tube 32 is mounted to the connection part 313 by use of a plurality of first connection pieces 33, for example, bolts or the like, passing through a plurality installation holes formed in the first installation flange 321, respectively. Also, a first seal pad 34 is provided between the installation end 323 and the connection part 313, so as to improve the sealing performance between the insulation connection tube 31 and the shield tail tube 32. The first connection pieces 33 pass through a plurality of through holes 341 formed in the first seal pad 34, respectively, and mount the shield tail tube 32 on the connection part 313.

In an embodiment, as shown in Figs.4-6, the connection part 313 radially protrudes outward beyond the outer tube 312, so as to form a second installation flange 314. The second installation flange 314 is mounted on the annular bottom plate 2 by means of second connection pieces 36, for example, bolts or the like, so as to mount the whole tail assembly 3 on the inlet end of the insulation tube 1 by means of the annular bottom plate 2. In this way, the assemble of the insulating connection tube 31 and the shield tail tube 32 may be completed in factory, and on field it only needs to connect the insulation connection tube 31 to the annular bottom plate 2, which simplifies the installation of the insulation termination assembly on field.

A second seal pad 35 is provided between the second installation flange 314 or the connection part 313, and the annular bottom plate 2. In an embodiment, an annular protrusion is formed on the connection part 313, and a slot for mating with the annular protrusion is formed in the annular bottom plate 2. The second seal pad 35 and the annular protrusion may both be engaged into the slot, so as to improve the seal performance between the second installation flange 314 and the annular bottom plate 2.

The shield tail tube 32 is provided with a connection part 322 which is used for connecting a grounding wire. In this way, the whole insulation termination assembly 100 may be grounded via the connection part 322.

As shown in Figs. l, 2 and 4, in an exemplary embodiment of the present invention, the insulation termination assemblylOO may further comprise a connection base 4 mounted at the inlet end of the insulation tube 1. The annular bottom plate 2 is mounted on the bottom of the connection base 4.

In an embodiment, the connection base 4 may be a single piece made of metal. In the illustrated embodiment, the connection base 4 comprises a third installation flange 41 and an auxiliary insulation tube 42 which are formed into a single piece. The third installation flange 41 is formed on the base of the auxiliary insulation tube 42. The auxiliary insulation tube 42 is connected to the inlet end of the insulation tube 1, and a portion of the inlet end of the insulation tube 1 is inserted into the auxiliary insulation tube 42.

In an embodiment, as shown in Fig.4, the connection base 4 further comprises a plurality of insulation reinforcing ribs 43 integrally formed with the third installation flange 41 and the auxiliary insulation tube 42. The plurality of insulation reinforcing ribs 43 each is connected to a surface of the third installation flange 41 and an outer wall of the auxiliary insulation tube 42, so as to increase the connection strength between the third installation flange 41 and the auxiliary insulation tube 42. The plurality of insulation reinforcing ribs 43 are evenly spaced and arranged around the base of the auxiliary insulation tube 42.

Fig.7 is an illustrative perspective view of a connection base 4', according to another exemplary embodiment of the present invention, for the insulation termination assembly of

Fig. l .

As shown in Fig.7, the connection base 4' comprises a third installation flange 4 and an auxiliary insulation tube which are formed into a single piece.

The auxiliary insulation tube comprises a first tube portion 42a, a second tube portion

42c, and a third tube portion 42b. The first tube portion 42a is located at one end of the auxiliary insulation tube adjacent to the third installation flange 4 . The second tube portion 42c is located at the other end of the auxiliary insulation tube far away from the third installation flange 4 . The third tube portion 42b is located between the first tube portion 42a and the second tube portion 42c. The first tube portion 42a has a constant first outer diameter, the second tube portion 42c has a constant second outer diameter less than the first outer diameter, and the third tube portion 42b has third outer diameters gradually decreasing from the first outer diameter to the second outer diameter. The second tube portion 42c of the auxiliary insulation tube is inserted into and connected to the inlet end of the insulation tube 1, for example, threaded to the insulation tube 1. The connection base 4' further comprises a plurality of insulation reinforcing ribs 43 ' integrally formed with the third installation flange 4 and the auxiliary insulation tube 42' . A plurality of installation holes 41a are formed in the third installation flange 41 ' . The third installation flange 41 ' may be connected to the annular bottom plate 2 by means of a plurality of bolts (not shown) passing through the installation holes 41a.

In this case, the insulation tube 1 is mated with the second tube portion 42c with a smaller diameter, instead of being mated with the third installation flange 41 ' with a larger diameter. Thereby, it reduces the diameter of the insulation tube 1, decreases the amount of material for manufacturing the insulation tube 1, and reduces the cost.

Also, in the above embodiments of the present invention, the inner diameter of the lower portion of the auxiliary insulation tube is larger than the inner diameter of the upper portion of it. The lower portion of the auxiliary insulation tube is just a location where the electric field is relatively concentrated. Thereby, it more effectively improves the insulation efficiency and reduces the cost because there is not a need to make the entire auxiliary insulation tube and the insulation tube 1 have the same diameter.

In the illustrated embodiments, the an inner diameter of the insulation tube 1 is slightly larger than the outer diameter of the second tube portion 42c of the auxiliary insulation tube 42 and less than the outer diameter of the first tube portion 42a of the auxiliary insulation tube 42. The inlet end of the insulation tube 1 is sleeved and connected to the outer wall of the second tube portion 42c of the auxiliary insulation tube 42.

In an exemplary embodiment, the connection base 4' and the insulation tube 1 may be made of the same insulation material. In this way, the connection base 4' and the insulation tube 1 have the same thermal expansion coefficient. Thereby, there is not easily to form a gap between the connection base 4' and the insulation tube 1. In another embodiment, the connection base 4' may be made of metal.

In an embodiment, the insulation tube 1 may be a winding tube formed by winding glass fiber impregnated with epoxy resin. The connection base 4' may be a pressed piece made of glass fiber impregnated with epoxy resin. In an embodiment, the inlet end of the insulation tube 1 may be wrapped and sealed onto the second tube portion 42c of the auxiliary insulation tube, so as to form a whole sealing structure, and improve the seal performance of the insulation termination assembly.

As shown in Fig.8, the cable 200 comprises a joint at a connection end thereof. The cable joint comprises a conductor core 210, an inner insulation layer 220 covered on the conductor core 210, a conductive shielding layer 230 covered on the inner insulation layer

220, and an outer sheath layer 240 covered on the conductive shielding layer 230. Before connecting the cable joint, it needs to remove a section of outer sheath layer 240 from the connection end of the cable to be connected, so as to expose a section of conductive shielding layer 230. Then, a portion of the exposed conductive shielding layer 230 is removed, so as to expose a section of inner insulation layer 220. Finally, a portion of the exposed inner insulation layer 220 is removed, so as to expose a section of conductor core 210. In this way, the cable joint to be connected is formed.

In an embodiment, as shown in Figs.l, 2 and 8, the insulation termination assembly 100 may further comprises a support seat 5 and a stress control cone 6 made of rubber material. The support seat 5 is mounted on a side of the annular bottom plate 2 opposite to the tail assembly 3 and extending into the inner space 12 of the insulation tube 1. The stress control cone 6 is mounted on the support seat 5. The stress control cone 6 is sheathed at least on a cut end of the conductive shielding layer 230 and a location of the inner insulation layer 220 adjacent to the cut end of the conductive shielding layer 230. The stress control cone 6 may prevent charges from being concentrated at the location of the inner insulation layer 220 adjacent to the cut end of the conductive shielding layer 230, and may protect the insulation tube 1 from being charged breakdown.

As shown in Figs.1-3, in an embodiment, the insulation termination assembly 100 may further comprises a conductive output bar 7. The conductive output bar 7 comprises a first end 71 extending out of the insulation tube 1 and a second end 72 inserted into the insulation tube 1 and connected to the first end 71. The second end 72 is located in the inner space 12 of the insulation tube 1. The second end 72 of the conductive output bar 7 is provided with a slot 721, the conductor core 210 of the cable 200 is adapted to be inserted into and engaged to the slot 721. The conductor core 210 is inserted into the slot 721 in an interference manner, so as to ensure a stable electrical connection between the conductor core 210 and the second end 72. A fixation member 9 is crimped on a joint of the conductor core 210 and slot 721, so as to further ensure the electric connection between the conductor core 210 and the second end 72.

In an embodiment, the insulation termination assembly may further comprises a high voltage shielding ring 8 detachably mounted on the outer wall of the outlet end of the insulation tube 1 and surrounding the first end of the conductive output bar 7. The high voltage shielding ring 8 is used to uniform the electric field produced at the first end 71 of the conductive output bar 7, so as to prevent the concentrated discharge.

According to the insulation termination assembly of the above various exemplary embodiments of the present invention, the cable introduced into the insulation tube is electrically shielded by the shield tail tube, and the shield tail tube is electrically isolated from the annular bottom plate made of metal by means of the insulation connection tube. In this way, the tail assembly is served as a support insulator, which may reduce the size of the annular bottom plate used for mounting the tail assembly, simplify the structure of the insulation termination assembly, and decrease the cost. Furthermore, the assemble of the insulating connection tube and the shield tail tube may be completed in factory, and on field it only needs to connect the insulation connection tube to the annular bottom plate by bolts. Thereby, it simplifies the installation of the insulation termination assembly on field. In addition, since the connection base and the insulation tube have the same or the similar thermal expansion coefficient, it is easy to connect the connection base and the insulation tube, and there is unlikely to form a gap between them, improving the seal performance between them.

It should be appreciated for those skilled in this art that the above embodiments are intended to be illustrated, and not restrictive. For example, many modifications may be made to the above embodiments by those skilled in this art, and various features described in different embodiments may be freely combined with each other without conflicting in configuration or principle.

Although several exemplary embodiments have been shown and described, it would be appreciated by those skilled in the art that various changes or modifications may be made in these embodiments without departing from the principles and spirit of the disclosure, the scope of which is defined in the claims and their equivalents.

As used herein, an element recited in the singular and proceeded with the word "a" or "an" should be understood as not excluding plural of said elements or steps, unless such exclusion is explicitly stated. Furthermore, references to "one embodiment" of the present invention are not intended to be interpreted as excluding the existence of additional embodiments that also incorporate the recited features. Moreover, unless explicitly stated to the contrary, embodiments "comprising" or "having" an element or a plurality of elements having a particular property may include additional such elements not having that property.