-All the facilities of house and outside wirings shall be closely installed not to ignite in explosive room
3.Countermeasure against vibration from transformer
-House and outside wirings shall be installed on the material to weaken the vibration or suspended in the air.
4.Measures against subsidence of the foundation
-Conductors shall have surplus length for absorbing their movement due to building sinking
Article 102. Connection of House and Outside Wirings
Connection of conductors shall comply with the following requirements.
-Tensile strength of conductors at connection point shall be secured not to be less than tensile strength at line parts of conductors. (except parts at where large tension is notapplied such as jumper parts.)
-Pressured connection sleeves shall be used at theconnection point, or connection of conductor shall be welded.
-Additionally, insulation of insulated conductors or cables at connection point shall be ensured not to be less than insulation at line parts by using connection boxes or winding insulation tapes.
Article 103. Cross-Sectional Area for Permanent Permissible Current
Cross-sectional area of conductors of house and outside wirings shall be determined based on the requirements in Chapter 2-2-1 of Vol.1 in Technical Regulation and this Guideline.
Chapter 2-3-2 Power Cable Line Systems with voltage up to 220kV
Article 104. Design and Construction Requirements
All the requirements for power cable lines in this Guideline shall be complied in consideration of policy in this article in Technical Regulation.
Article 105. Cable Route Selection
The route of power cable lines shall be selected in consideration of limitation for roads and firefighting as well as social environment of the route and be avoided the following places as much as possible.
- Narrow roads where the traffic of cars and peoplexpectedis |
to be blocked during the |
construction works. |
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-Places near hospitals or schools, where serious problems are easily caused by noise and vibration of the cable works.
-Places near gas stations or storage of explosive materials.
-Places with corrosive gas or waste drainage
-Approaches of shrines or temples
-Shopping streets where a large number of people pass by.
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In the area with harmful substances (e.g. soil with salt, or electro-chemical corrosion, cables shall be used protective covers.
mud, ash) to steel, the construction machines which are with aluminum sheath and plastic
Article 106. Requirements in the Installation and Operation Process
Refer to the requirements in Chapter 7 in Part 6 in Technical Regulation and GuideVol.ine3for specific procedures and methods of installation of power cable lines.
Article 107. Protective Cables
1. Requirements against corrosion
The vinyl and the polyethylene with the following characteristics are generally preferable as the material of the protective covering outer sheath to protect the cable from corrosion.
(1)High insulation and high dielectric strength are possessed andesdonot decrease over a long period of time.
(2)Waterproof, oil-proof, chemical resistance and flame resistance are possessed, and a chemical characteristic is stable over a long period of time.
(3)Excellent weather resistance and resistance to aging are possessed.
(4)Abnormality does not appear in temperature of the outer sheath of the cable operated generally (About -10°C to 70°C).
(5)Mechanically strong, excellent flexuous and abrasion resistance are possessed, and friction coefficient is not large.
(6)Manufacturers can process easily.
Table 107 |
Characteristic of protective covering outer sheath |
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Item |
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Material of protective covering outer sheath |
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Vinyl |
Polyethylene |
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Anti-damage |
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G |
G |
Anti-friction |
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G |
G |
Heat resistance |
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G |
G |
Cold resistance |
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G |
VG |
Anti-weatherability |
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G |
G |
Anti-ozone |
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VG |
G |
Anti-aging |
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G |
G |
Flame resistance |
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VG |
P |
Anti-chemical |
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G |
VG |
Waterproof |
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G |
VG |
Anti-fungus |
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VG |
G |
Anti-radial ray |
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G |
G |
Note:VG:Very good, G:Good, P:Poor
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2.Requirements against sunlight
As for the parts of power cable lines exposed directly to sunshine, the cables are preferable to be installed in pipes or trough for avoiding aging of protective covering outer sheath and rising temperature of the parts.
3.Requirements against heat source
When power cable lines go nearby the heat resources and they are heated by the heat resources, the permissible current of power cable liens is limited. Therefore, power cable lines are preferable to be installed far away from the heat resources.
If power cable lines cross or go nearby heat pipelines, requirements in article214 of Vol.1 in Technical Regulation and this Guideline shall be complied.
4.Requirements against explosion
-Cables shall be installed in pipes which can withstand the explosion.
-All facilities of power cable lines shall be closed not to ignite in an explosive room
5.Requirements against flame
Power cable lines installed in cable tunnels shall have the measures for protecting the flame.
-To Use cables with protective covering outer sheath made of non-flammable or flame resistance materials.
-To cover cables by tapes or paint made of non-flammable or flame resistance materials.
-To install cables in pipes or trough made of non-flammable or flame resistance materials.
Article 108. Factors in Calculations for Underground Cables
Buried pipes which power cable lines are installed shall be 3 times stronger than the withstand loads shown in the following formula.
W=W1+W2+W3+W4
W : Distributed load applied to buried pipes (kN/m2) W1: Pressure of the earth (kN/m2)
W2:Vehicle load passes on ground surface (kN/m2)
W3: Enhanced pressure of earth after earth retaining walls for the excavation work are removed (kN/m2)
W4: Distributed weight of buried pipes and cables (kN/m2)
Article 109. Cable Placement Requirements
Cable structures as well as cables shall be made of nonflammablematerials. (Refer to article107 in this Guideline)
Even if temporary cable structures are used only in a shortperiod of time, they shall satisfy all the requirements in Technical Regulation and Guideline.
Article 110. Bended Cable
Bending radius of cables shall be more than permissible bending radius shown in the following table.
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Table 110 |
Permissible bending radius |
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Kind of cable |
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Permissible bending radius (m) |
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Oil-filled |
Aluminum sheath |
Single core |
15×(Cable radius) |
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cable |
Triple cores |
12×(Average twisted radius) |
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No metallic sheath |
Single core |
10×(Cable radius) |
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XLPE |
Triple cores |
8×(Average twisted radius) |
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cable |
Aluminum sheath |
Single core |
15×(Cable radius) |
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Stainless sheath |
Single core |
17.5×(Cable radius) |
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Remark: Permissible bending radius specified by the manufacture can apply.
Article 111. Cable Tension
Cable tension shall not be exceeded permissible tension as below.
-Cables with copper core: 68.6*N*A (N)
-Cables with aluminum core: 39.2*N*A (N)
N : Number of cores of cable
A : Cross sectional area of cable (mm2)
As reference, calculation formulae of cable tension are shown in the following table.
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Table 111 |
(Reference) Calculation formulae of cable tension |
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Installation |
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Figure of installation |
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Calculation formula |
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T µWL |
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Straight and |
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T : Cable tension |
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µ : Friction coefficient |
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flat section |
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W : Weight of cable a meter |
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L : Length of cable |
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(1) In case of incline |
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T1 WL(µcosφ +sinφ) |
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Straight and |
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φ : Angle of inclination |
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Other symbols means the same as above |
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incline or |
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(2) In case of decline |
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decline section |
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T2 WL(µcosφ −sinφ) |
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φ : Angle of declination |
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Other symbols means the same as above |
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Bigger tension in two formulae is adopted |
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−1 T1 |
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T2 WRsinh µθ |
+sinh |
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Curve and flat |
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WR |
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T2 T1 |
cosh(µθ)+ |
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T12 +(WR)2 sinh(µθ) |
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section |
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R : Curvature radius |
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θ : Horizontal angle |
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Other symbols means the same as above |
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Article 112. Nameplate
Nameplate (sign) shall comply with the requirements in article 479 to 482 in GuidelineVol.4.
Article 113. Routes of Cable Underground or Underwater
Measurement for mapping the route of power cable lines shall be conducted as below.
-Measurement is conducted along the center axis of the route
-The scope of measurement includes buildings and structures, etc. within 10m from both side edges of the road.
- Altitudes of main measurement points such as inflection point of the road are measured from existing benchmarks or special landmarks precisely.
- Auxiliary measurement points are set at the interval of 20m.
Road
Center axis of the route
Main measurement
Auxiliary measurement
Figure 113 (Sample) Map of the route
Article 114. Arrangement Pattern
1. Arrangement for power cable lines with voltage up to 35kV
-The number of cables in cable canal shall be up to 6.
-In case that the number of cables is more than 6, power cable lines shall be arranged in cable tunnels, cable bridge, cable trench, corridors or separated cable canals spaced not less than 0.5m.
-In case that many cables are gathered atintersection with railways or roads, the power cable lines shall be arranged in cable blocks in order to avoid breaking sheathes each other.
2.Arrangement in power station
-Power cable lines shall be arranged in cable tunnels, blocks, trough, bridges or corridors.
-Six or less power cable lines for auxiliary structures which are far from power plant (e.g. fuel depot, workshop) are permitted to be arranged in cable canals.
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