JP3663103B2 - Ground fault prevention method for OF cable connecting part and offset part - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a ground fault disaster prevention method in a connecting portion and an offset portion of an OF cable (oil-insulated power cable).
[0002]
[Prior art]
In general, the connecting part of the OF cable used as a high-voltage underground transmission line and its offset part are provided with a disaster prevention function to prevent secondary disasters such as fire caused by a ground fault. It has become.
[0003]
For example, as shown in FIG. 10, the connecting portion and the offset portion of the conventional OF cable are covered with a box-shaped FRP trough a or a rubber disaster prevention tape b to ensure airtightness. Even if the cable is ignited due to a ground fault, the fire is immediately extinguished by the suffocation effect of the trough a and the disaster prevention tape b to prevent the occurrence of a fire.
[0004]
In addition, when this ground fault occurs, not only ignition but also a rapid pressure increase around the blast is generated. For example, the trough a and the disaster prevention tape b are surrounded by a high tension band c such as stainless steel or aramid. The device is devised to improve the pressure resistance against the blast at the same time by bundling at intervals.
[0005]
[Problems to be solved by the invention]
By the way, when an ultra-high-pressure OF cable is used in the future, the pressure and ignition power due to the blast at the time of the ground fault will increase accordingly, and there is a possibility that the secondary disaster cannot be sufficiently prevented only by the above-described device.
[0006]
That is, when the pressure due to the blast generated at the time of the ground fault increases, the high tension band c that binds the trough a covering the connection part breaks and the trough a opens, or the disaster prevention tape b at the offset part cracks. As a result, a sufficient suffocation effect may not be obtained, and ignition may continue and lead to a fire.
[0007]
Therefore, the present invention has been devised to effectively solve such problems, and its purpose is to ensure excellent pressure resistance and airtightness even when a large ground fault occurs. The present invention provides a novel method for ground fault prevention in an OF cable connecting portion and an offset portion that can exhibit a sufficient suffocation effect.
[0008]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the first invention is to surround the OF cable connecting portion with a trough so that a constant pressure-reducing space is formed around the OF cable connecting portion, and a belt-like aramid fiber sheet directly on the entire outer peripheral surface of the trough A ground fault disaster prevention sheet consisting of a double sheet consisting of an inner sheet and an outer sheet made of an aramid fiber, in which the entire outer periphery of the aramid fiber sheet is uniformly covered, and the entire periphery of the aramid fiber sheet is directly sleeved. It is intended to cover.
[0009]
Therefore, the entire trough is uniformly reinforced by winding a belt-shaped aramid fiber sheet directly around the entire outer circumferential surface of the trough and covering the entire outer circumferential surface uniformly . Compared with the case where the blast pressure is applied, the bombardment pressure can be uniformly received by the belt-shaped aramid fiber sheet, and the pressure resistance of the trough against the blast pressure can be improved. And even if it is damaged by this blast by covering the entire periphery of the aramid fiber sheet with a ground fault disaster prevention sheet consisting of a double sheet of an inner sheet and an outer sheet that are directly sleeved, Since the air-tightness disaster prevention sheet maintains the airtightness of the surrounding area and maintains the suffocation effect, even if ignition occurs, the fire extinguishes immediately and does not cause a fire.
[0010]
The second invention, the ground fault prevention sheet, the inner sheet and having a suture portion extending in the width direction of the OF cable joint, sutures of the outer sheets extending in the longitudinal direction of the OF cable connection Yes and, and using those to a state in which these seamed portions intersect each other, further suturing unit is used in conjunction with superposed on the multiplexed configured stitched for each suit each lap. That is, since the pressure due to the blast generated at the time of the ground fault is applied not only in the width direction but also in the longitudinal direction of the ground fault disaster prevention sheet, the inner sheet and the outer sheet in which the directions of the stitched portions made of aramid fibers intersect each other By forming from, sufficient strength can be exhibited not only in the radial direction but also in the longitudinal direction. As a result, the ground fault disaster prevention sheet will not be broken even if an extremely high explosion pressure is applied so that the trough and the aramid fiber sheet are damaged, and excellent airtightness can be maintained.
[0011]
In the third aspect of the invention, the reinforced ground fault disaster prevention sheet is further covered with a highly airtight sheet, whereby the air tightness of the ground fault disaster prevention sheet itself can be further enhanced.
[0012]
According to a fourth aspect of the present invention, the offset portion of the OF cable is surrounded by a flexible tube so that a constant pressure-reducing space is formed around the offset portion, and the inner sheet and the outer side of the sleeve-shaped aramid fiber are enclosed. The ground fault disaster prevention sheet is a double sheet and a ground fault disaster prevention sheet, and the ground fault disaster prevention sheet further includes a stitched portion in which the inner sheet extends in the width direction of the OF cable connecting portion, and the outer sheet is the OF cable. have a sewn portion extending in the longitudinal direction of the connecting portion, and with which they seamed portion was set to be in a state of crossing each other, further sewn portion is stitched together are superimposed on multiplex each combined each lap It is configured . As in the first aspect of the present invention, even if a ground fault occurs at the offset portion, the explosive pressure is released in the longitudinal direction of the cable along the pressure avoidance space formed by the tube. In addition to preventing damage, even if the tube is damaged, the ground fault disaster prevention sheet covered around it maintains the airtightness of the offset part and maintains the choking effect. Fires can be reliably prevented. Moreover, by this, similarly to said 2nd invention, the intensity | strength and airtightness of a ground fault disaster prevention sheet | seat by the side of an offset part can be improved more.
[0013]
In the fifth invention, as in the third invention, the ground fault disaster prevention sheet is further covered with a highly airtight sheet. Thereby, like the third invention, the strength and air tightness of the ground fault disaster prevention sheet on the offset portion side can be further improved.
[0014]
The sixth invention is a combination of the ground fault prevention method for an OF cable connection part according to any one of claims 1 to 3 and the ground fault prevention method for an offset part according to claim 4 or 5 described above. The trough cable through port on the OF cable connecting portion side and the tube end portion on the offset portion side are connected so that the trough and the tube communicate with each other. Thereby, the ground fault disaster prevention of the OF cable connecting portion and the offset portion can be performed at the same time. In addition, by setting the trough and the tube in communication with each other, the pressure caused by the blast generated in either the trough or the tube escapes to the other pressure-relief space and increases locally. Therefore, the trough or tube can be prevented from being damaged due to a ground fault.
[0015]
7th invention is sewn so that the ground fault disaster prevention sheet end part by the side of OF cable connection and the ground fault disaster prevention sheet end part by the side of the above-mentioned offset may continue. Thereby, since there is no break between the ground fault disaster prevention sheet on the OF cable connection side and the ground fault disaster prevention sheet on the offset part side, it is possible to prevent a decrease in strength and airtightness in the vicinity of the boundary.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Next, a preferred embodiment for carrying out the present invention will be described with reference to the accompanying drawings.
[0017]
1 and 2 show an embodiment of a ground fault prevention method in an OF cable connecting part and an offset part according to the method of the present invention, where C is an OF cable, S is the OF cable C, The connection part between C and R is the offset part.
[0018]
As shown in the figure, the OF cable connecting portion S is provided with a trough 1 made of FRP having a box shape so that a fixed pressure-reducing space is partitioned around the OF cable connecting portion S. The aramid fiber sheet 2 is wound around the trough 1 in a roll shape so as to uniformly cover the entire surface, and a ground fault disaster prevention sheet 3 having a sleeve shape is formed on the aramid fiber sheet 2. A coating is formed.
[0019]
On the other hand, the offset portion R is flexible with a diameter larger than that of the OF cable C so that a constant pressure-reducing space (gap) is formed around the OF cable C as shown in FIGS. It is covered with a tube 4 made of plastic or the like, and a ground fault disaster prevention sheet 5 made of aramid fiber having a sleeve shape is also formed around the tube 4.
[0020]
As shown in FIG. 1, the end of the tube 4 is connected to the cable through hole 6 formed at the end of the trough 1, and the trough 1 and the tube 4 are connected through the cable through hole 6. Are in communication with each other.
[0021]
Here, the ground fault prevention sheet 3 and 5 for use in the present invention is not just a single aramid fiber sheet, as shown in FIG. 4, respectively and outer side sheet 7 made of aramid fibers and an inner side sheet 8 It consists of a double sheet that is overlapped and sewn together at both ends 3a, 3b.
[0022]
The inner sheet 8 has one or more stitching lines 11 extending in the circumferential direction (width direction) of the cable C, and the outer sheet 7 extends in the longitudinal direction of the cable C. It is formed from one having one or more suture lines 11.
[0023]
That is, first the outer side sheet 7 arranges an oblong sheet piece goods 10, 10 in the width direction of the cable C, and a rectangular to each other the edges of adjacent sheets piece goods 10, 10 sewn by sewing machine or the like It is formed on a horizontally long sheet. On the other hand, the inner side sheet 8 is previously arranged plurality which is cut into strips (4 sheets in the present embodiment) seat cloth 9,9,9,9 in parallel in the axial direction of the cable C, as well The edges of adjacent sheet fabrics 9, 9 are sewn together by a sewing machine or the like to form a rectangular sheet having a rectangular shape.
[0024]
Also, both longitudinal end portions 3a of the ground fault prevention sheet 3, 5, 3b, together with the superimposed so as to wrap the end portion of the inner side sheet 8 the end portion of the outer side sheet 7 as shown in FIG. 5 that The wire or the reinforcing rope 12 is wrapped along the inside, and the overlapping portion is integrally formed by sewing along the length direction. Then, as shown in the drawing, a plurality of metal fitting mounting holes 13 are perforated along the overlapping portion with a predetermined interval, and both end portions 3a and 3b are overlapped to form the entire sheet into a sleeve shape. As shown in FIG. 3, the overlapped end portions 3a and 3b are sandwiched between a pair of sewing metal fittings 14 and 14, and both sewing metal fittings 14 and 14 are respectively bolts 15, 15. It is possible to easily create the ground-fault disaster prevention sheets 3 and 5 in the form of a sleeve by fastening at the site. In addition, since this ground fault disaster prevention sheet | seat 3 and 5 differs in the diameter of the corresponding connection part S and offset part R, respectively, the edge part by the side of the ground fault disaster prevention sheet 3 by the side of the connection part S is gradually adjusted for diameter adjustment. By squeezing so as to squeeze and sew it to the end of the ground fault disaster prevention sheet 5 on the offset portion R side, both are connected to each other via this sewing portion.
[0025]
And since this invention employ | adopted the disaster prevention method as mentioned above, the outstanding disaster prevention effect can be exhibited by the effect | action and effect as shown below.
[0026]
First, as described above, the flexible tube 4 is provided on the offset portion R side, and the tube 4 and the trough 1 on the connection portion S side are in communication with each other. Since the pressure of the blast due to the ground fault can escape instantaneously to the other side (longitudinal direction) through the cable through hole 6, the local pressure increase in the radial direction at the site where the ground fault has occurred is suppressed, It becomes possible to prevent the trough 1 or the tube 4 from being damaged. As a result, the airtightness of the connecting portion S and the offset portion R is maintained, so that even if ignition occurs due to a ground fault, the suffocation effect is maintained and the ignition immediately extinguishes, and the occurrence of fire due to continued ignition Can be prevented in advance.
[0027]
Next, even when the blast pressure is high and the trough 1 or the tube 4 is damaged by such a method, the ground fault disaster prevention sheets 3 and 5 provided around the trough 1 or the tube 4 cause a ground fault. Since the airtightness of the connected portion S and the offset portion R can be maintained, the fire is immediately extinguished by the suffocation effect of the ground fault disaster prevention sheets 3 and 5 even if ignition occurs in the same manner, and the occurrence of fire is surely prevented. can do. Further, the ground fault prevention sheet 3, 5 is made of stitching direction different outer side sheet 7 and the inner side sheet 8 Metropolitan as described above, and, relatively strong weak sewn portions 11, 11 ... each sheet 7 can because in a state of intersecting each other at 8, in which not only the width direction of the cable can sufficiently withstand the pressure exerted in the longitudinal direction. Further, the ground fault disaster prevention sheets 3 and 5 are configured such that the end portions 3a and 3b are connected to each other by the sewing metal fittings 14 and the bolts 15, and therefore can be easily provided on the trough 1 at the site. Moreover, the connecting portion of the end portion 3a, 3b, because they are firmly connected to the other suture 11 or by sewing brackets 14 and bolts 15 as described above, the solution or torn sheeting from this portion There is nothing to do.
[0028]
Moreover, since the edge part of the ground fault disaster prevention sheet 3 by the side of a connection part S and the ground fault disaster prevention sheet 5 edge part by the side of an offset part R are mutually stitched together, both have become the state of continuous, and the intensity | strength of the boundary vicinity And a decrease in airtightness can be suppressed at the same time. In addition, if a thread that is weaker than the fiber strength of the sheet 3 is used as a sewing thread that is used for pinching so that the end portion of the ground fault disaster prevention sheet 3 on the connection part S side is squeezed, the sheet is generated when a blast occurs. Since the sewing thread itself is cut before the 3 is fully expanded, a part of the explosion pressure is absorbed, so that the explosion pressure applied to the sheet 3 itself can be further reduced.
[0029]
In addition, each parameter, such as the kind of material which comprises the ground fault disaster prevention sheet | seats 3 and 5 mentioned above, the number of windings, or the thickness of a trough, changes variously with the kind, environment, etc. of the object OF cable C. For example, in the case of a ground fault capacity of 45 kA × 0.4 seconds with a 275 kVOF cable, the maximum pressure rise of the seat internal pressure is about 4.13 MPa, and the average pressure rise is a ground fault on the connection side. When the disaster prevention sheet 3 has a diameter of 500 mm, it is predicted to be about 1.24 MPa. For this reason, the specifications of the aramid sheet etc. corresponding to this are as follows: Basic specification of sheet: Filament fabric: 3000 denier x 3000 denier 17 x 16.5 pieces / inch, roll sheet winding number: about 3 times, connection trough thickness : About 6 mm.
[0030]
In addition, as shown in FIG. 7, the stitching portions 11 of the sheets 7 and 8 constituting the ground fault disaster prevention sheets 3 and 5 are overlapped in quadruplicate, and sewing is performed for each overlap. Even if some sewing threads are cut off by the blast, as long as the remaining sewing threads are connected, the airtightness of the sheet is maintained, so that the initial choking effect can be maintained. In addition, the blast pressure can be gradually reduced by cutting off some of these sewing threads.
[0031]
Further, as shown in FIG. 8, by covering the stitched portion 11 with a fireproof sheet (silica sheet) 16, it is possible to prevent the sewing thread from being burned and cut due to initial ignition.
[0032]
Further, as shown in FIG. 9, if the surroundings of the ground fault disaster prevention sheets 3 and 5 are further covered with a highly airtight sheet 17, for example, an aramid sheet 19 whose surface is coated with PVC or the like 18, ground fault disaster prevention It is possible to improve the airtightness of the sheets 3 and 5 themselves and further improve the suffocation effect.
[0033]
【The invention's effect】
In short, according to the present invention, since excellent pressure resistance and airtightness can be exhibited in the connection part and offset part of the ultra-high pressure OF cable, it is a case where a high explosion pressure or ignition occurs due to a ground fault. In addition, it is possible to exert excellent effects such as reliably preventing the occurrence of fire due to cable breakage due to explosion pressure or continuation of ignition.
[Brief description of the drawings]
FIG. 1 is a conceptual diagram showing an embodiment of a method of the present invention.
FIG. 2A is a cross-sectional view taken along the line AA in FIG.
(B) is the elements on larger scale which show A section in Drawing 2 (a).
FIG. 3A is a cross-sectional view taken along the line BB in FIG.
(B) is the elements on larger scale which show the A section in Fig.3 (a).
FIG. 4 is a partially broken perspective view showing the structure of a ground fault disaster prevention sheet used in the method of the present invention.
FIG. 5 is a partially enlarged view showing a part A in FIG. 4;
FIG. 6 is an explanatory view showing a state in which ends of the ground fault disaster prevention sheet are joined together with a sewing metal fitting.
FIG. 7 is an explanatory view showing a stitching method of a sewing portion of an inner sheet and an outer sheet.
8 is a partially enlarged view showing a portion B in FIG. 4. FIG.
FIG. 9 is an enlarged cross-sectional view showing a state in which a high density sheet is stacked on the ground fault disaster prevention sheet according to the present invention.
FIG. 10 is a conceptual diagram illustrating an example of a ground fault prevention method in a conventional OF cable connecting portion and an offset portion.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Trough 2 Aramid fiber sheet 3, 5 Ground fault disaster prevention sheet 4 Tube 6 Cable through-hole C OF cable S Connection part R Offset part

Claims (7)

The OF cable connection is surrounded by a trough so that a constant pressure-reducing space is formed around it, and a belt-like aramid fiber sheet is directly wound around the entire outer circumferential surface of the trough so that the entire outer circumferential surface is uniform. An OF cable connecting portion characterized by covering and further covering the entire periphery of the aramid fiber sheet with a ground fault disaster prevention sheet comprising a double sheet of an inner sheet and an outer sheet made of aramid fiber that is directly sleeved Earth fault disaster prevention method. The ground fault prevention sheet, the inner sheet and having a suture portion extending in the width direction of the OF cable connection, have a sewn portion where the outer sheet extending longitudinally of the OF cable connection, and these sutures 2. The OF cable according to claim 1, wherein a portion that crosses each other is used , and the stitching portions are overlapped and stitched for each overlap. Ground fault prevention method for connecting parts.   The ground fault disaster prevention method according to claim 1 or 2, wherein the ground fault disaster prevention sheet is further covered with a highly airtight sheet. The offset portion of the OF cable is surrounded by a flexible tube so that a certain pressure-reducing space is formed around it, and the tube is a sleeve-shaped double sheet of an inner sheet and an outer sheet made of aramid fiber The ground fault disaster prevention sheet is further covered with a ground fault disaster prevention sheet, and the ground fault disaster prevention sheet has a stitching portion whose inner sheet extends in the width direction of the OF cable connection portion, and the outer sheet extends in the longitudinal direction of the OF cable connection portion. extending the suture portions have a, and using what they seamed portion was set to be in a state of crossing each other, further stitching unit, characterized in that with superposed on the multiplexed configured stitched for each combined each lap The ground fault disaster prevention method of the offset part. The ground fault disaster prevention method according to claim 4 , wherein the ground fault disaster prevention sheet is further covered with a highly airtight sheet. A combination of the ground fault prevention method for an OF cable connection part according to any one of claims 1 to 3 and the ground fault prevention method for an offset part according to claim 4 or 5, and the OF cable connection part. A ground fault in the OF cable connecting portion and the offset portion, wherein the cable through hole of the side trough and the tube end portion on the offset portion side are connected to communicate with each other in the trough and the tube. Disaster prevention method. The OF cable connecting portion according to claim 6 , wherein the end portion of the ground fault disaster prevention sheet on the OF cable connection portion side and the end portion of the ground fault disaster prevention sheet on the offset portion side are stitched together. Ground fault disaster prevention method in the offset part.

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