It is permitted to decrease the width of the passage on narrow ground to 0.6 m.
Section 5 CABLE INSTALLATION INSIDE BLOCK AND PIPE
Article 438. Progress inspection
The check contents below should be followed
1.Cable route
The cable route is the most important element related to the future management(at the house and the road in the surrounding, the offset distance with other buried objectsand maintenance work in the future). Therefore, the center position and the length of the power cable line, the ground level and the row condition of the cable canal should be checked.
2.Depth of laying underground cable (amount of digging)
Depth of laying undergroundcable is an important element that influences the earth load by the
weight of soil andvehicle going though the |
earth |
surface |
over |
the cable canal, and has |
implications to the strength of the cable canal . |
The |
depth of |
the |
hole to bury thecable canal |
should be checked surely, because the earth load by the weight of soil increases when the distance from the cable canalto the earth surface is too long, and the earth loadby the weight of vehicle increases when the distance is too short.
3.Waterproof processing
It should bechecked that the seam in thecable canal and the lid are tightly shutto prevent underground water form penetrating.
4.The distance from top surface of the cable canal to earth surface (the amount of backfill soil)
The distance from top surface of the cable canal to earth surface should be confirmed that it is appropriate, since the cable canal might be broken if the distance is inappropriate.
Article 439. Works for connecting points
The bump and the gap are generated easilyat the joint point of the cable canal and the cable block. The joint point should be checked before pulling the cable, and be made smooth by jointadjustment and applying slipping powder, because the cable may be damaged due to the bump and the gap.
Article 440. Duct Cable size limitation
When the outside diameter of the cableis too large compared with the inside diameter of thecable block, the stress due to friction by the rigidity of the cablemay be higher than the stressdue to the cable’s own weight at the curved part of the cable block. Therefore, the maximum outside diameter of cable which can be pulled into the cable block should satisfy the following formula.
(Outside diameter of cable) ÷ (Inside diameter of cable block) = (85 % or less)
Article 441. Cables installation in cables pipes
Refer to Chapter 3-2-4 in Technical Regulation Vol.1.
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Article 442. Cable installation on cable pit
Refer to Article 433 in this Guideline.
Article 443. Inserting cable into block
The treatment of neutral conductor should be applied before installing the cable, because it may be difficult to handle the cable after installing in the cable block.
Article 444. Inspection before cable installation
The mandrill size of each cable blockdiameter (outside diameter and length) is as shown inthe following table. However, the value ofthis table should be applied tothe cable block of which bending radius is 10 m or more, and the outside diameter and the length of the test pipe for the cable block of which bending radius is less than 10m should be examined individually by below formula.
Figure 444 |
Test pipe |
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Table 444 Size of test pipe of each cable block diameter |
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Inside diameter of cable block : d (mm) |
100 |
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125 |
150 |
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175 |
200 |
outside diameter of test pipe: D (mm) |
90 |
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115 |
140 |
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165 |
190 |
length of test pipe: L (mm) |
600 |
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600 |
600 |
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600 |
600 |
[Formula of the maximum length of test pipe]
L ≤ 2 ×
(R +d )2 −(R + D)2 (mm)
R : Bending radius of cable block (mm) d : Inside diameter of cable block (mm) D : Outside diameter of test pipe (mm)
Outside diameter of test pipe is generally 10mm less from inside diameter of cable block. (D = d – 10mm)
Article 445. Inspection of duct
Visual check by pipe camera
Video camera is inserted inthe cable block to confirm thesituation in thecable block. There are several types of methods for inserting the camera as shown in the following table.
When underground water |
has been infiltratedinto the cable blockvoluminously, the |
damage or the |
gap of joint part ofthe |
cable block may occur. The defect should be found |
and be repaired |
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immediately, because the following damage is assumed when earth and sand outside of cablethe block flows in.
-It is impossible to use the cable block due to blocking of earth and sand.
-Sinking of ground level along the flow of earth and sand on the cable block
Table 445 Visual check by pipe camera
Type |
Method |
Advantage |
Disadvantage |
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The wire is passed in |
It is easy to confirm the |
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situation in the cable |
The wire needs to be |
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a. Wire pulling |
an empty cable block, |
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block because the position |
passed in the cable block |
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type |
video camera is pulled |
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of camera can be adjusted |
in advance. |
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in. |
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by the wire. |
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A small vehicle with |
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It is difficult to turn the |
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position of camera exactly |
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b. Self-propelled |
video camera is made |
The preparation work is |
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because a self-propelled |
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type |
to run in an empty |
not required in advance. |
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vehicle goes forward by |
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cable block. |
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the fixed velocity. |
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The whole aspect of inside |
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It is applicable not only in |
cable block can not be |
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Video camera attached |
seen, only the upper |
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c. One pushing |
at the edge of carbon |
an empty cable block but |
aspect of inside cable |
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rod is pushed by |
also a cable block inserted |
block can be confirmed. |
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human power. |
cable. |
The applicable length is |
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limited by the length of |
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carbon rod. (up to 150m) |
Section 6 CABLE INSTALLATION AT SWAMP, MUDDY REGION AND UNDER
WATER
Article 446. General
When the cable is constructed in the curve section, the sedimentary soil and the water ditch, itshould be constructed in the cable block to fix the cable position since the power (power returns bending and power where the soil and water move) may work to make the shift the position.
Article 447. Requirement of cable installation place
Even if the cable damage is minute,it might decrease the dielectric strength and the corrosion-proof performance.
The obstacle which the cable might be damaged should be removed in consideration of the range of the cable movement hat is caused by the ambient temperature change, the heat contractionand expansion according to the energizing situation.
Article 448. The depth of installed cables
Depth of laying undergroundcable and the construction method should be complied with the design materials according to the traffic of shipsand the situation of river.(Refer to Chapter 3-2-6 in Technical Regulation Vol.1)
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Article 449. The distance between the cable
When the cable is constructed, the surpluslength of the cable should be considered todeal with the change and the trouble of operated cable.
The surplus length of the cable is shown in Chapter 3-2-6 in Technical Regulation Vol.1.
The cable section that goes to river should be processed as shown in the designmaterials. (Refer to Chapter 3-2-6 in Technical Regulation Vol.1)
Article 450. Installation cables at collapsed position
The bank cable is laid underground should be prevented from collapsing because the cable might be damaged in the event of the collapse. (Refer to Chapter 3-2-6 in Technical Regulation Vol.1)
Article 451. Prohibition of cable intersection in the water
Intersecting cables in water is prohibited as shown in Article 231 in Technical Regulation Vol.1
Article 452. Notice sign
The notice sign at intersection point between the cable and the river should be installedas shown in Article 232 in Technical Regulation Vol.1
Section 7 CABLE CONNECTION AND CABLE HEAD MAKING
Article 453. Cable head making
Main materials of the cable head |
of theoil-filled cable should be materials shown |
in the following |
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table. |
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Table 453 Main material of oil-filled cable head |
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Type |
Material |
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Check content |
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It should not havedefects such as a void, |
damage and a |
Hollow porcelain |
Porcelain |
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crack, and be superior to water absorptive resistant, andits |
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material should be strong and coated with glaze. |
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It should not have a electric and mechanical defect, cracks and |
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Epoxy-resin |
Epoxy-resin |
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other harmful defects,a harmful cavity and peeled layer |
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Bushing |
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internally, and it should be made ofan excellent material that |
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has stable characteristics against the SF6 gas. |
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Article 454. Material of connection box
The quality of the material of a cable connection box should be as shown in the following table.
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Table 454 Material of cable connection box
Voltage |
Cable covering |
Material of connection box |
Construction place |
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outer sheath |
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3 kV or more |
Aluminum, Lead |
Epoxy, Copper, Lead, Bronze |
- |
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Less than 1 kV |
Aluminum, Lead |
Cast iron |
The earth (directly buried) |
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- |
Nothing |
Lead, Epoxy |
- |
Article 455. Cables installed directly which have a joint
The offset distance from the connection box to the cable should be as shown Article 212 in Technical Regulation Vol.1, and the defense measuresshould be as shown Article210 in Technical RegulationVol.1.
When the pull force by the cable’s self-weight works at the connection box, and the connection box is corroded by the corrosion water, theconnection box should not be installedvertically. When it is necessary by all means, the horizontal dry placeshould be prepared for the cable installation,and the connection box should be installed at a state without the pull force and corrosion water.
Article 456. Connection of cable in blocks
When the cable isinstalled in the cable block, the cable roomfor the cableconnection should be installed at appropriate intervals (generally 300m or less) that meet the following requirements.
1.Cable pulling tension should not exceed the permitted tension of cable.
2.Cable pulling tension should not exceed the permitted tension of the hook for pulling the cable in the cable room.
3.Cable pulling lateral pressure should not exceed permitted lateral pressure.
4.Cable length of one span should not exceed maximum winding length of drum (Maximum winding length of drum is limited by transportable weight of the drum winded cable and tension capacity of cable pulling machine).
5.Sheath voltage to ground should not exceed 50V.
Article 457. Cable joint with rubber cover
Terminal processing and connected processingshould be conducted in consideration of the following matters by understanding specifications and the site assembly manual ofetc. each material completely.
1.Terminal processing and connected processing should be conducted in the way that impurities are not mixed inside the insulator and the cable is not bended too much.
2.As a rule, neither a terminal processing nor connected processing should be conducted during rain excluding indoor. When a rainfall starts while processing, the processing should be discontinued and the cable terminal and the material should be covered with the cover so that the drop of water does not adhere to them, and other waterproof processing should be conducted.
3.The sign which identifies the date of processing and the name of construction contractor should be installed at terminal and connection location.
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