JP2000350342A - Hanging jumper device and prefabricated wire for multiconductor transmission line - Google Patents

Abstract

PROBLEM TO BE SOLVED: To employ a prefabricated overhead line installation method when a wire anchoring method with a wedged clamp and a hanging jumper device are employed. SOLUTION: In a hanging jumper device 21 for a multiconductor transmission line, the multiconductor transmission lines 1 are anchored by the arm 4 of a strain tower on both the sides of the arm 4 with wedged clamps 12, yokes 6 and tension insulator strings 5, the center parts except both sides of jumper wires 3 formed between both wedged clamps 12 on both sides of the tower are laid horizontally along a rigid horizontal member 8 hung by the yoke 6 with support members 9 therebetween, and the jumper wires 3 are supported by spacers 11 arranged in the longitudinal direction of the rigid horizontal member 8 with intervals. The horizontal parts 3b of the jumper wires 3 which are laid along the rigid horizontal member 8 are used an excessive length parts which are bent into a U-shape with a size within a range containable in the inner space of a group of a plurality of jumpers 3 to absorb excessive lengths.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a suspension type jumper device in which an intermediate portion except for both side portions of a jumper wire is attached to a rigid horizontal member. With regard to the suspension type jumper device applied to the type to be retained on the tension tower, particularly when manufacturing the electric wire, the electric wire in the section of one extension line is measured and marked to the length determined and precisely measured and calculated in advance. The present invention relates to a suspension type jumper device for a multi-conductor transmission line suitable for a prefabricated wire line construction method in which a prefabricated wire is used by using a prefabricated wire, and a prefabricated wire used for the same.

[0002]

2. Description of the Related Art A suspended jumper device 7 as shown in FIG. 7 is conventionally used as a jumper device in a tension portion of an ultra-high voltage overhead transmission line. In the figure, reference numeral 1 denotes a multi-conductor power transmission line, 2 denotes a span portion (span wire), and 3 denotes a jumper portion (jumper wire). Reference numeral 4 denotes a tower arm, reference numeral 5 denotes a tension insulator series, and reference numeral 6 denotes a yoke located on the span side of the tension insulator series 5.

[0003] This suspension type jumper device 7 has a jumper.
In order to minimize the clearance required for electrical insulation between the wire 3 and the tower arm 4, a rigid horizontal member 8 made of a rigid shaped steel material or a steel pipe material is horizontally arranged below the arm 4, and both ends thereof are yokes. 6 is suspended via a supporting member 9 and spacers 11 for holding the jumper wire 3 are attached to both ends and an intermediate portion of the rigid horizontal member 8 at intervals, and the intermediate portion except for both side portions of the jumper wire 3 is attached to this. In this configuration, the spacer 11 is attached to the rigid horizontal member 8. The jumper wire 3 in the suspension type jumper device 7 is a portion between the jumper outlets (arrows 13) of the wedge-type clamps 12 on both sides of the tower of the transmission line 1, and the jumper outlet 1 of the wedge-type clamps 12
The both sides of the rigid horizontal member 8 which have slack between the spacer 11 and the end of the rigid horizontal member 8 have a jumper wire free portion 3a, and the intermediate portion gripped by the spacer 11 and attached to the rigid horizontal member 8 is a jumper wire horizontal portion. 3b.

The lengths of the support member 9 and the rigid horizontal member 8 are determined by the coordinates of the yoke 6 located on the span side of the tension insulator series 5 for retaining the span electric wire 2 installed on the steel tower, the required clearance, and It is determined and calculated by calculating a jumper shape based on an angle (suspension angle) formed between the support member 9 and the rigid horizontal member 8, and the like. The support member 9 is generally provided with a length adjusting portion (not shown) for adjusting the clearance on site. For the length of the free portion 3a of the jumper wire 3, the same jumper shape calculation is performed, and the jumper outlet 13 of the wedge clamp 12 is obtained.
Then, the actual length between the spacers 11 provided at the end of the rigid horizontal member 8 is calculated, and the required number of jumper spacers is determined based on a predetermined interval between the jumper spacers 14 to manufacture.

[0005] The suspension type jumper device 7 is generally constructed in the following procedure. Connect the span wires 2 to the tension insulators 5
When securing to the wedge-type clamp 12 at the tip of the above, the required jumper wire length calculated by the above-described jumper shape calculation is calculated by adding the extra length for the construction work from both sides of the tower (younger and older). Make a deal. After the support member 9 and the rigid horizontal member 8 assembled on the ground are lifted and attached to the yoke 6, the free portion 3a of the jumper wire 3 is secured,
The remaining portion (the portion to be the jumper line horizontal portion 3b) is linearly attached to the rigid horizontal member 8 and is gripped by the spacer 11. In this case, since the extra length is expected from the beginning in the jumper wire 3 as described above, the rigid horizontal member 8 is not linearly attached as it is. Then, in order to attach the jumper wire 3 to the rigid horizontal member 8 in a straight line, the jumper wire 3 is cut between the spacers 11, formed into a straight line, and adjusted in length. Compression connection.

For the purpose of labor saving in overhead wire work, for example, in a case where a suspension tower is located at an intermediate position by an electric wire retaining system using a wedge-type clamp 12, the wedge-type clamp installation position and the suspension clamp installation position in each of the towers at the time of manufacturing the electric wire. In recent years, a prefabricated wire line method of extending a wire using a marked prefabricated electric wire has been adopted. In this case, for the prefabricated electric wire, the distance between the wire support points between the respective diameters to be overlaid is precisely measured, and the distance between the support points of the tension yoke of the tower arm, the length of the tension insulator, and the specified sag are taken into consideration.
It is manufactured by obtaining the actual wire length of one extension line section, measuring the length of the prefabricated wire to a length corresponding to the required wire actual length, and marking the wire when manufacturing the wire. Then, the prefabricated wire is extended by using the prefabricated electric wire, attaching the wedge-type clamp 12 to the prefabricated electric wire in accordance with the marking, and connecting the wedge-type clamp 12 to the tension insulator series 5. In the case of the tension tower, assuming that the suspension jumper device 7 is employed, the actual jumper wire length obtained by the jumper shape calculation as described above is added to the above-described actual wire length when manufacturing the electric wire. Then, after the wire is drawn, a tightening operation (sagging adjustment work) is performed so as to match the specified sag.
Next, the rigid horizontal member 8 and the support member 9 are lifted and attached to the yoke 6, and then the free portion 3a of the jumper wire 3 is secured, and the jumper line horizontal portion 3b is linearly attached to the rigid horizontal material 8, and the spacer 11 Hold with. This completes the function as a transmission line including the suspension type jumper device 7 which is a current path.

[0007]

However, since the purpose of the prefabricated wiring method is labor saving and cost reduction, no extra time is required for the above-mentioned construction work even in the construction of the suspended jumper device 7. It is a premise. Therefore, the jumper wire 3 between the spacers 11
Adjustment of the jumper length by cutting of the jumper and compression connection of the jumper wire 3 by the jumper sleeve 16 are not performed. However, errors are caused by factors such as errors in prefabrication calculation and prefab measurement, errors in precision surveying, errors in jumper shape calculations, errors in the rotational elongation of the electric wire and the elongation of the running wheel, and errors in execution. As described above, generally, a sag adjustment bracket 17 whose length can be adjusted by about ± 100 mm is interposed between the wedge-shaped clamp 12 and the yoke 6.
It has a structure that can absorb errors on the span side.

However, when the wedge-type clamp 12 is used, since the span wire 2 and the jumper wire 3 are continuous, the adjustment result on the span side directly affects the formation of the suspended jumper device 7. become. In addition, it is conceivable that the wedge-type clamp 12 is replaced to adjust the wedge mounting position. However, since it is necessary to minimize damage to the electric wire due to wedge driving, the number of wedge replacements is limited. . For this reason, it is necessary to absorb the error substantially only by the suspension type jumper device 7, and as a result, the free portion 3a of the jumper wire 3 becomes irregular, insufficiently loosened, excessively loosened, and the like. There is a disadvantage that a large man-hour is required.

In a general prefabricated overhead wire construction method, when determining the wire support point spacing, precise surveying is performed between all wire support points (ie, between six support points in the case of a two-circuit tower). In recent years, for the purpose of further cost reduction, adoption of a method of performing only surveying between towers at a steel tower position, that is, a method based on surveying between towers has been studied.
In this case, in addition to the above-mentioned error factors, factors such as the installation error of the tower, the deflection of the tower, and the like will be added, and in the case of the suspension type jumper device, it will be impossible to adopt the prefabricated wiring method. .

The present invention has been made in view of the above circumstances, and relates to a case in which a multi-conductor power transmission line is retained by a wedge-type clamp, and a suspension type jumper device is employed as a jumper device. An object of the present invention is to provide a suspended jumper device for a multi-conductor power transmission line that can be adopted, and a prefabricated electric wire used for the same.

[0011]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention secures a multi-conductor power transmission line through a wedge-type clamp, a yoke, and a string of insulators on both sides of an arm in a tension tower, respectively. An intermediate portion of the jumper wire formed between the wedge-type clamps, except for both sides, is horizontally attached to a rigid horizontal member suspended from the yoke on both sides of the tower via a supporting member, and the rigid horizontal member is While being supported by spacers arranged at intervals in the longitudinal direction, a part of the jumper line horizontal portion is gripped by the spacer as a surplus portion at a jumper line horizontal portion along the rigid horizontal member of the jumper line. A jumper line extra length portion formed in a U-shape within a range that can be accommodated in the inner space portion of the plurality of jumper line groups.

A second aspect of the present invention is characterized in that, in the first aspect, a spacer for holding the jumper wire is additionally provided at a position near the extra length of the jumper wire of the jumper wire in the rigid horizontal member.

A third aspect of the present invention is characterized in that, in the first aspect, the extra length of the jumper line is formed at a plurality of positions of the same jumper line in the horizontal portion of the jumper line.

According to a fourth aspect of the present invention, there is provided a prefabricated electric wire for constructing a multiconductor power transmission line employing the suspension jumper device for a multiconductor power transmission line according to the first aspect of the present invention by a prefabricated wiring method, comprising a wedge-type clamp and a yoke. The jumper shape length L1 obtained by performing the jumper shape calculation based on the jumper exit of the wedge-shaped clamp at the maximum extension position of the sag adjustment fitting provided between the maximum length in consideration of the jumper shape calculation error and the manufacturing error The sum of the jumper wire actual length L2 (L2 = L1 + ΔLmax) to which the error length ΔLmax is added and the span wire actual length L3 calculated based on the jumper outlet of the wedge-shaped clamp is defined as the actual wire length L4 (L4 = L2 + L3). When manufacturing an electric wire, prefabricate the length to match the actual wire length L4 and mark the position corresponding to the jumper outlet of the wedge-type clamp. It is characterized by having given.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A suspension type jumper device for a multiconductor power transmission line according to an embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a side view of a suspended jumper device 21 according to one embodiment. In the figure, reference numeral 1 denotes a multi-conductor power transmission line, 2 denotes a span portion (span wire), and 3 denotes a jumper portion (jumper wire). Multi-conductor transmission line 1 in the illustrated example
Is a four-conductor power transmission line composed of four elementary conductors 1a, as shown in FIG. 2A showing the AA cross section of FIG. Reference numeral 4 denotes an arm of the tension tower, 5 denotes a series of tension insulators, and 6 denotes a yoke located on the span side of the series of tension insulators 5.

The suspension type jumper device 21 includes a rigid horizontal member 8 made of a rigid shaped steel material or a steel pipe material for minimizing a clearance required for electrical insulation between a jumper wire and a tower arm. 4 is hung horizontally below the yoke 6 via a support member 9, and spacers 11 for holding the jumper wire 3 are attached to both ends and an intermediate portion of the rigid horizontal member 8 at intervals. An intermediate portion of the jumper wire 3 except for both side portions is attached to the rigid horizontal member 8 by the spacer 11. The jumper wire 3 in the suspension type jumper device 21 is a portion between the jumper outlets (arrows 13) of the wedge-shaped clamps 12 on both sides of the tower of the transmission line 1, and the jumper outlet 1 of the wedge-shaped clamps 12
The both sides of the rigid horizontal member 8 which have slack between the spacer 11 and the end of the rigid horizontal member 8 have a jumper wire free portion 3a, and the intermediate portion gripped by the spacer 11 and attached to the rigid horizontal member 8 is a jumper wire horizontal portion. 3b.

The length of the support member 9 and the rigid horizontal member 8 are determined by the coordinates of the yoke 6 located on the span side of the tension insulator series 5 for retaining the span electric wire 2 installed on the steel tower, the required clearance, and It is determined and calculated by calculating a jumper shape based on an angle (suspension angle) formed between the support member 9 and the rigid horizontal member 8, and the like. The support member 9 is generally provided with a length adjusting portion (not shown) for adjusting the clearance on site. For the length of the free portion 3a of the jumper wire 3, the same jumper shape calculation is performed, and the jumper outlet 13 of the wedge clamp 12 is obtained.
Then, the actual length between the spacers 11 provided at the end of the rigid horizontal member 8 is calculated, and the required number of jumper spacers is determined based on a predetermined interval between the jumper spacers 14 to manufacture.

The present invention employs a prefabricated wire-line construction method, and the prefabricated electric wire to be used is at the maximum extension position of the sag adjusting bracket 17 provided between the wedge-type clamp 12 and the yoke 6 (ie, The jumper shape calculation error and the manufacturing error are taken into account in the calculated jumper wire length L1 obtained by performing the above-described jumper shape calculation based on the jumper outlet 13 of the wedge-shaped clamp 12 (when the sag adjustment metal fitting 17 is most extended). The sum of the jumper wire actual length L2 (L2 = L1 + ΔLmax) to which the maximum error length ΔLmax is added and the span wire actual length L3 calculated on the basis of the jumper outlet 13 of the wedge-shaped clamp 12 is calculated as the actual wire length L4 (L4 =
(L2 + L3), the wire is prefabricated to a length that matches the actual wire length L4 when the wire is manufactured, and the wire is manufactured by marking the position corresponding to the jumper outlet 13 of the wedge clamp 12. Note that the above-mentioned actual length L3 of the span wire is calculated in consideration of the suspension tower in the middle, if any.

When the prefabricated electric wire manufactured as described above is used for wiring by the prefabricated wire-laying method, after the prefabricated electric wire is passed through the wheel of each tower, a wedge-type clamp 12 is attached to each tower. Is attached to the span wire 2 in accordance with the marking on the prefabricated wire,
Further, it is connected to a yoke 6 located on the span side of the tension insulator string 5 attached to the tower arm 4 via a sag adjusting bracket 17, and the sag of the span wire 2 is adjusted by the sag adjusting bracket 17. I do. Thereby, the work of tightening the span wires 2 is completed. The above operation is performed for each elementary conductor 1a of the multiconductor transmission line 1.
Do about.

After the above tightening work is completed, the rigid horizontal member 8 to which the support members 9 and the spacers 11 are attached in advance is lifted on the ground, and this is hung on the yoke 6 via the support members 9 and the jumper The free portion 3a of the wire 3 is formed so as to secure a predetermined shape, and the jumper wire 3 is gripped and fixed by the spacers 11 provided at both ends of the rigid horizontal member 8, and then the jumper wire 3 is fixed. The portion to be attached to the rigid horizontal member 8 (the portion that becomes the jumper line horizontal portion 3b) is the rigid horizontal member 8
Is temporarily held on the spacer 11 provided at the intermediate portion of the above. Next, as shown in FIG. 3 in an enlarged manner, a plurality of jumpers gripped by the spacer 11 are used as extra lengths, with a part of the jumper wire horizontal portion 3b along the rigid horizontal member 8 of the jumper wire 3 as an extra length. It is formed in a U-shape within a range (in the embodiment, inside a quadrangle (in FIG. 2B, a dashed-dotted quadrangle) formed by the four elementary conductors 1a) that can be accommodated in the inner space of the group of three lines. That is, the U-shaped extra jumper line portion 3c is formed. Next, after the spacer 11 in the intermediate portion is fully tightened to grip and fix the jumper wire 3, the shield spacer 22 for preventing the electric field from being discontinuous due to the opening of the U-shaped extra jumper wire portion 3c is removed. It is attached to the opening of the extra-length jumper wire portion 3c in the shape of a letter. The shield spacer 22 has gripping portions at both ends, and grips the base (opening portion) of the U-shaped extra jumper line portion 3c with the gripping portions at both ends. Then
As shown in FIG. 2 (b), the top of the U-shaped extra jumper wire portion 3c is fitted to a gripping clamp 24 provided on the rigid horizontal member 8 to fix it inside the bundle conductor of the jumper wire 3 (3b). And fix them together.

The jumper wire 3 is made of a stranded wire having the same structure as that of the span wire 2. Generally, a steel core aluminum stranded wire is used, so that the jumper wire 3 itself has a large bending rigidity. It is impossible to form the U-shaped extra jumper line portion 3c in the inner space of the group by human power. Therefore, as shown in FIG. 4, the left and right fixed rollers 25 and the intermediate movable roller 26 are arranged so as to support three or five points, and the movable roller 26 is hydraulically driven to make the jumper wire 3 move.
Extra length forming tool 27 for applying U-shaped plastic deformation to (3b)
May be used to form a U-shaped jumper extra length 3c. The extra jumper wire portion 3c is entirely formed in the inner space portion. However, since the lower surface of the jumper wire 3 located on the lower side has no scaffolding and is difficult to form, the extra jumper wire portion 3c is not provided above the lower surface. Formed on the surface of (ie,
Except for the top portion, it is preferable to form so as not to come into the hatched area in FIG. Since the length of the extra jumper wire portion 3c varies depending on the adjustment result of the span wire 2 and the jumper free portion 3a, if the extra wire length is short as a result of the adjustment, the top of the extra jumper wire portion 3c is required. It is also possible to dispense with fixing the to the rigid horizontal member 8 by the grip clamp 24. If the depth of the U-shaped extra jumper line portion 3c is about 50 mm, the shield spacer 22 for preventing discontinuity of the electric field can be omitted.

Regarding the material of each member, the rigid horizontal member 8 is a shaped steel or a steel pipe, the support 9 is a mild steel, the jumper spacer 14, the spacer 11, and the holding clamp 24 are an aluminum alloy casting or an aluminum alloy casting. The shield spacer 22 such as a combination of mild steel materials is preferably an aluminum alloy casting.

When the extra length of the jumper wire 3 is curved into a U-shape to form the U-shaped extra jumper wire portion 3c, the narrower mounting interval of the spacers 11 on both sides of the jumper wire 3 is determined when the extra jumper wire is taken in. 3 is restricted, which is advantageous in the operation of forming a U-shape. Therefore, as shown in FIG.
By additionally installing the spacer 11 'near the position where the extra jumper line portion 3c is formed, the spacer interval is reduced, and the operation of forming the extra jumper line portion 3c becomes easier.

If the extra length 3c of the jumper wire formed on each element conductor 1a of the jumper wire 3 cannot be accommodated in the space inside the jumper wire group, as shown in FIG. A jumper extra length portion 3c (two locations in the illustrated example) may be provided at a plurality of locations in the length direction. Provision at a plurality of locations is effective in increasing the adjustment allowance.
That is, even if the extra length is set to the jumper wire, it can be easily absorbed. The U-shaped jumper wire extra length 3c, which is so shallow as not to cause discontinuity of the electric field, is not limited to the case where it can not be accommodated in the inner space portion as described above, and the length of the jumper conductor 1a is the same. When the extra length is provided at a plurality of positions in the direction to absorb the extra length, it is possible to omit the fixing to the rigid horizontal member 8 by the shield spacer 22 and the holding clamp 24, which is economically effective.

In each of the embodiments described above, the suspension type jumper device for the 4-conductor power transmission line has been described. However, the number of conductors is arbitrary, and the suspension-type jumper device for the 3-conductor or 6-conductor transmission line or other multi-conductor transmission lines is used. The present invention can be applied to an apparatus.

[0026]

According to the present invention, when a multi-conductor power transmission line is to be wired by using a suspension type jumper device as a jumper device in a wire retaining system using a wedge-type clamp, the extra length of the jumper wire is used. Is formed in a U-shape at a portion along the rigid horizontal member of the jumper wire and absorbed, so that the extra length of the jumper wire can be absorbed by the suspension type jumper device. Therefore, even if it is not necessary to cut the jumper wire to eliminate the extra length and reconnect with a jumper sleeve as in the conventional case, the slackness adjustment result of the span wire such as irregularities in the free portion of the jumper wire can be obtained. The effect can be eliminated. As a result, it became possible to construct a multiconductor transmission line using a suspension type jumper device as a jumper device by an electric wire retaining method using a wedge-type clamp by a prefabricated wiring method.

In addition, according to the method of forming a U-shape to absorb the extra length, the amount of absorption of the extra length of the jumper wire (capture length) can be increased, so that a book having a wide sag adjustment range is required. It is also possible to adopt a prefabricated overhead line construction method using point-to-point surveying.

[Brief description of the drawings]

FIG. 1 is a side view showing a suspended jumper device for a multiconductor power transmission line according to an embodiment of the present invention.

2A is a cross-sectional view taken along the line AA of FIG. 1, and FIG. 2B is a cross-sectional view taken along the line BB of FIG.

FIG. 3 is an enlarged side view of the vicinity of an extra length of a jumper line in FIG. 1;

FIG. 4 shows the construction of the suspension type jumper device of the present invention.
It is a figure of the extra length forming tool used for forming a U-shaped extra jumper line part.

FIG. 5 is an enlarged side view showing another embodiment of the present invention and corresponding to FIG. 3;

FIG. 6 shows still another embodiment of the present invention, and is an enlarged side view corresponding to FIG.

FIG. 7 is a side view showing a conventional suspended jumper device.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 multi-conductor transmission line 1 a elementary conductor 2 span wire 3 jumper wire 3 a jumper wire free portion 3 b jumper wire horizontal portion 3 c extra length of U-shaped jumper wire 4 steel tower arm 5 tension insulator series 6 yoke 8 rigid horizontal material 9 Supporting material 11 Spacer 12 Wedge clamp 13 Jumper outlet of wedge clamp 14 Jumper spacer 17 Sag adjuster 21 Suspended jumper device 22 Shield spacer 24 Gripping clamp 25, 26 Roller 27 Extra length forming tool

Claims (4)

[Claims] 1. A wedge-type clamp (1) is provided on each side of an arm (4) of a tension tower with a multiconductor transmission line (1).
2), while retaining it via the yoke (6) and the tension insulator string (5), wedge-type clamps (1
2) The middle part of the jumper wire (3) formed between the two parts except the both sides is connected to the horizontal yoke (6) on both sides of the tower by a rigid horizontal member (8) suspended via a support member (9). A jumper wire that is attached horizontally and supported by spacers (11) arranged at intervals in the longitudinal direction of the rigid horizontal material (8), and that the jumper wire (3) is attached to the rigid horizontal material (8). In the horizontal portion (3b), as a surplus portion, a part of the jumper line horizontal portion (3b) is in a range where the part of the jumper line horizontal portion (3b) fits in the inner space portion of the plurality of jumper line (3) groups held by the spacer (11). A suspended jumper device for a multi-conductor power transmission line, comprising a jumper wire surplus portion (3c) formed in a U-shape. 2. A spacer (11 ') for gripping the jumper wire (3) is additionally installed at a position of the jumper wire (3) in the rigid horizontal member (8) close to the extra length of the jumper wire (3b). The suspension type jumper device for a multi-conductor power transmission line according to claim 1, wherein: 3. The multi-conductor transmission according to claim 1, wherein said extra jumper line portion (3c) is formed at a plurality of positions of the same jumper line (3) in said jumper line horizontal portion (3b). A suspended jumper device for electric wires. 4. A prefabricated electric wire for constructing a multiconductor power transmission line employing a suspension type jumper device for a multiconductor power transmission line according to claim 1 by a prefabricated wiring method, comprising a wedge-type clamp (12) and a yoke. And (6) a jumper shape obtained by performing a jumper shape calculation based on the jumper outlet of the wedge-shaped clamp (12) at the maximum extension position of the sag adjusting bracket (17), and a jumper shape. The actual jumper line length L2 (L2 = L1 + Δ) to which the maximum error length ΔLmax considering the calculation error and the manufacturing error is added.
Lmax) and the actual wire length L3 calculated on the basis of the jumper outlet of the wedge-shaped clamp (12) as the wire actual length L4 (L4 = L2 + L3). A prefabricated electric wire which is prefabricated to a length corresponding to a predetermined length and is marked at a position corresponding to a jumper outlet of the wedge-shaped clamp (12).