Article 196. Distance from Live Parts
The distance between conductors of soft outside wirings shall not be less than 6 times of the diameter of conductors.
Also, reference for the distance from live parts ofsoft outside wirings with voltageexceeding 1kV to 35kV are followings.
-Distance between live parts: 245 and 266
-Distance from live part to earthing: 275
-Distance from live part to buildings and other structures: 246 and 270
-Distance from live part to car roads: 293
-Distance from live part to railways: 291
Article 197. Condition for the Checking Distance
In consideration of the distance between phaseconductors or conductors in multipleconductors, the maximum temperature shall be selected by the specification of the conductors.
The maximum temperature after the fault shall been taken by specification of the manufacturer, if that not, that shall been taken by 70°C.
Article 198. Expected Location of Earthing Connection for Extension of Soft Outside Wirings
The number of earthing connection points shall be determined by earthing means and the induced voltage which comply with the requirements in article 194 in this Guideline.
Article 199. Calculating Conditions for Soft Outside Wirings
In the calculation of soft outside wirings, normally the tension force in a phase shall not exceed 9.8kN.
Chapter 3-2 Power Cable Line Systems with Voltage up to 220kV
Chapter 3-2-1 The Selection of Cables
Article 200. Requirement for Different Environmental Conditions
For power cable lines with thelength less than thelength of a roll of cabletraverse the area with different condition of installation environment, Cross-sectional area and structures of the cables shall be selected according to the harshest conditions
For power cable in long lines which installed under the water, the lines with maximum three different types of cross-sectional areas are permitted to be used in one cable route
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Article 201. The Selection of Cables and Protection
1. |
Selection of sheath |
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(1) |
Cables of power cable lines laid underground or in the water shall have sheathes which can |
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withstand mechanical load (the pressure of the water or the earth). Wherever the |
lines are |
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installed, sheathes of the cables shall withstand mechanical load, frictional force for pulling the |
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cables in cable blocks, etc. as well as the impacts of heat or chemical substances during operation |
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or maintenance. |
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(2) |
Single-phase cable alternating current (AC) must not be usedwith protective shell made |
of |
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magnetic materials. |
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2. Selection of protective measures
(1)Cable trough
Cable troughs of oil-filled cables with high pressure shall have protective measures against corrosion.
(2)Production hall, etc.
In the production workshops without the risk of mechanical damage, power cable lines are permitted to be used unarmored cables, but inthe production workshops with high risk, the lines shall have protective armors or protective measures.
Unarmored cables are permitted to be installed at the height not less thanm2outside the cable structures. Unarmored cables installed at the height less than 2m shall have protective measures such as cable pipes, etc.
Cables with metallic sheaths installed in the cable structures or production halls shall not have external protective covers. Also, cables without metallic sheaths shall not be made of flammable materials.
Cables installed openly are prohibited to have flammable polyethylene insulations.
Metallic sheaths or parts of cables shall be covered by -corrosionanti coating made of nonflammable materials. If power cable lines are installed in corrosive environment, the cables which can withstand the corrosion from the environment shall be used for the lines.
3. Selection of cable
(1)Power station, etc.
In power stations, substations or important points of the power network, powerthe cables with metallic sheaths and covers made of non-flammable materials shall be use for cable lines. In power stations, cables with the sheaths made of flammable materials shall not be used for the lines.
(2)Cable block, etc.
For power cable lines installed in cable blocks and pipes, it is permitted to use unarmored cables with reinforced lead sheaths.
In the section of cable blocks or branches, it is permitted to use armored cables with lead or aluminum sheaths without external protective covers made of fibers for power cable lines.
For power cable liens installed in cable blocks, it is permitted to use cables with sheaths made of rubbers or polyvinylchloride.
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(3)Unstable area
Power cable lines installed in unstable area shall be wire-armored cables or have protective measures against the movement of soil (e.g. surpluslength of cables, compacting soil, driving stakes).
(4)Stream, etc.
Cables used for underground or underwater shall be selected as power cable lines traverse the stream, alluvial flat or canal in consideration of ducking them in the water or burying them in the ground. (Refer to 210 and 229)
(5)Bridge
Cables with aluminum sheathes shall be used for power cable lines installing along the bridge.
(6)Mobile equipment
The flexible cables which can withstand movement or bending many times shall be used for power cable lines supplying electricity to mobile equipment.
(7)Underwater
Power cable lines installed underwater |
shall be armored cables with steel strands. The |
connections of cables underwater are prohibited. Thus, it is prone to be used single core cables |
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which are manufactured easily in long length. |
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Cables with double metallic covers or sheaths shall be used for the power cable lines in places |
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such as the seas with big waves, fastflowing- |
rivers, banks tend to be eroded, and underwater |
with the depth from 40m to 60m. |
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Cables with rubber insulations inpolyvinylchloride sheaths and cables with aluminum sheaths without sealing coats are prohibited to be used underwater.
Armored cables are permitted tobe used in alluvial flats not larger than 100m with steady water flow of small rivers without any traffic.
(8) Laying
Cables, cable terminals and cable connection boxes shall be used not to exceed the permissible values stipulated in the specifications at vertical sections or slopes of power cable lines.
Power cable lines shall be arranged as below to absorb the shrinkage of the cables due to the heat generated by operation current of power cable lines.
-Cable: wavy laying and arrangement (arrangement like snake shape)
-Connection box: lay on the sliding rack
(9)Cable core
In power cable lines with voltage up to35kV with 3 phase network, the three-cores cables shall be used preferentially for the linesor single-core cables shall be selectedafter calculating, comparing technical and economical benefits
The temperature increase of the sheaths due to induced current of neighboring cables shall be taken into account for cross-sectional area of single-core cables..
In above-mentioned cases, measures to identify each operation current of cables going in parallel, to ensure safety for person touching protective covering outer sheaths and to minimize the heat transferred to adjacent metallic sheaths shall be applied, and the cables shall be fixed by insulated clamps.
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Article 202. Design for Oil-Filled Cables
The design for oil-filled cables shall comply with this article in Technical RegulationVol.1.
Article 203. Installation of Neutral Conductor
Neutral conductors shall be installed in compliance with requirements in this article inchnicalTe RegulationVol.1.
Article 204. Oil Cable Systems
Oil cable systems shall comply with this article in Technical RegulationVol.1.
Chapter 3-2-2 Installation of Cable Connection Boxes and Cable
Terminals
Article 205. Installation of Cable Connection Boxes and Terminals
1. Rubber cable
As for cables with flexible rubber insulations and rubber coats, the connection shall be performed by hot curing (autoclave curing) the rubber; and the connection points shall be covered by waterproof layers.
2. Number of connection boxes
Maximum number of cable connection boxes in one kilometer of power cable lines is shown inthe following table.
Table 205 |
Maximum number of connection boxes per 1 km |
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Voltage |
Cross-sectional area |
Referential maximum |
Cable core |
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number of cable |
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(kV) |
(mm2) |
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connection boxes |
Single-core |
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Not stipulated |
Not stipulated |
2 |
Triple-cores |
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Exceeding 1 to 10 |
Up to 95 |
4 |
Triple-cores |
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Exceeding 1 to 10 |
From 120 to 240 |
5 |
Triple-cores |
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15, 22, 35 |
Not stipulated |
6 |
Single and triple-cores |
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Not stipulated |
Not stipulated |
determined by design |
Article 206. Requirements for Cable Connection Boxes
The lenqgth of section between connection boxes |
and installation positions of ones shall be |
determined in consideration of the following requirements. |
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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. Length of a cable for oneconnected section should not exceed maximum winding length ofa cable drum (Maximum winding length of a drum is limited by transportable weight considering the weight of a cable winded to a drum and tension capacity of cable pulling machine).
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