Article 253. Lightning Protection

Metal parts of cables connected to overhead power lines shall be grounded.

Lightning protective equipment shall be installed at the location shown in the following table:

Article 254. Insulation Distance

Correction of minimum insulation distance by altitude

On overhead power lines with voltage exceeding1kV traverse at altitude area, the minimum insulation distance shown in Table 254 in Technical RegulationVol.1 shall be increased by 1.4%for every additional 100m once it exceeds 1,000 m.

Article 255. Minimum Distance between Conductors at Branch or Phase Transposition Pole

The minimum distance betweenconductors at special poles (transposition or branch poles, etc.) of overhead power lines with voltage exceeding 1kV shall not be less than the values shown in Table 255 in Technical RegulationVol.1.

Chapter 3-3-6 Poles

Article 256. Kinds of Poles

1.Kind of poles

(1)Support poles shall be arranged between two straight anchorpoles. These poles do not need to bear the force along the overhead power lines in normal conditions.

(2)Anchor poles shall be arranged at anchor points in straight sections of the overhead power lines

and at intersection with other structures. These poles shall bear the difference of forces between front and back spans in normal conditions, if any.

(3) Corner poles shall be arranged at bending points of the route of overhead power lines. These poles are permitted to be utilized as support and anchor poles. These poles shall bear combined force in next spans by bisector of the route of the lines.

(4) Dead end poles (breaking poles) shall be arranged at thebeginning and end of overhead power lines. These poles shall bear the force which all conductors are pulled toward one side.

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(5) Branch pole shall be arranged at points where overhead power lines branch two or more directions.

(6)Crossing poles (intersection poles) shall be arranged at points where two or more different overhead power lines cross each other.

(7)Transposition poles shall be arranged at transposition points of overhead power lines.

(8)Special poles shall be arranged at special points except the points of above-mentioned poles.

2.Other requirement for pole

- Guys are permitted to be usedfor all poles depending on site conditions except the place where they obstruct the traffic.

-Site locations for anchor poles shall be determined based on operation and installation conditions.

-The anchor section of overhead power lines withconductors with cross-sectional area not more

than 185mm2 installed by fixed or slidelocks shall not be more than 5km, and the section with cross-sectional area more than185mm2 shall not be more than 10km.

- The span-lengths of conductors connected to fixed locks or -posttype insulators shall be determined by site conditions of overhead power lines.

Article 257. Anchor Wires

Anchor wires (guys) are permitted to be connected to underground anchor foundations, bricks, stones, reinforced concrete buildings and structures.

Anchor wires shall be selected by the calculations according to the load, and cro-sectionals area of them shall not be less than 25mm2.

Article 258. Calculation of Poles

1.Calculation on pole of overhead power line with voltage up to 1kV

(1)Support pole: The load to the route of the lines and poles in horizontal direction due to wind perpendicular.

(2)Anchor pole: The load to the route of the lines and poles in horizontal direction due to wind perpendicular, and the load along the route of overhead power lines in horizontal direction due to

the difference of tension of conductors between front and back spans.

(3)Corner pole: The load in horizontal direction due to tension of conductors and the load in horizontal direction due to wind acting conductors and poles.

(4)Dead end pole (breaking pole): The load along the route of overhead power lines in horizontal direction due to tension of conductors to one side.

2.Calculation on pole of overhead power line with voltage exceeding 1kV

(1)Anchor pole: The load along the route of overhead power lines in horizontal direction due to the difference of tension of conductors and lightning conductor between front and back spans.

(2)Poles with double circuits: The load shall be checked, which only oneircuit is installed in all conditions. It shall be checked the load in conditions for installation and erection of poles as well as condition for installation of conductors and lightning conductor.

3.Normal condition for pole of overhead power lines with voltage exceeding 1kV

Poles in normal conditions shall be calculated in the following conditions.

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-Conductors and lightning conductors are not broken and the maximum wind pressure is taken into account (qmax).

-When representative span-length of corner poles is shorter than ultimate one, the minimum

conductors and lightning conductors is applied to one side of them, and the conditions as there is

no conductors and lightning conductors in opposite side such as spans beside substations and adjacent to large overcrossing span.

4.Fault condition on pole of overhead power lines with voltage exceeding 1kV

(1)Support pole

The maximum bending torque and maximum twisting torque at support poles with conductors fixed by suspension-type insulators shall be calculated in the following fault conditions.

1)Breakage of conductor and lightning conductor

-One and more conductors of one phase (at any number of conductors on a pole) are broken. Lightning conductors are not broken.

-All conductors are not broken. One lightning conductor is broken.

2)The load which conductors and lightning conductors are not broken shall be considered.

3)Standard tension of single conductor by strain insulation set, in the case that one conductor is broken, is stipulated in the following talbe. However, for other poles (poles made of new

materials, metal poles with flexible structures, etc.) than which shownni the following table, it shall be calculated with the coefficient depending on the bending level on poles within the range shown in the following table.

*Note: Tmax means the maximum tension of single conductor in fault condition.

4)In fault condition that multiple conductors in one phase on support poles of overhead power lines with voltage up to220kV are broken, standard tension of one conductor in multiple conductors shall be determined by applying the same condition as single conductor in one phase

of overhead power lines. Standard tension in one phase shall be multiplied the number of conductors in one phase by the following coefficient.

-Two conductors in one phase: 0.8

-Three conductors in one phase: 0.7

-Four conductors in one phase: 0.6

5)Standard tension of lightning conductors shall be 0.5TLmax. TLmax means the maximum tension of lightning conductor in fault condition

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Standard tension in the case that lightning conductors of overhead power linesth voltagewi exceeding 1kV on reinforced concrete poles without guys are broken, are permitted to be determined in consideration of the flexibility of the poles.

6) In the fault condition that multiple conductors in one phase on support poles of overhead power lines with voltage of500kV are broken, the load of one phase at the point the conductors are fixed shall not be less than 0.15Tmax and 18kN.

(2) Anchor pole and dead end pole (breaking pole)

Anchor and Dead end poles in fault conditions shall be calculated in consideration of the maximum bending torque and the maximum twisting torque generated in the following cases.

-All conductors of one phase in one span at any circuits on the pole are broken. Lightning conductors are not broken.

-All conductors are not broken. One lightning conductor is broken.

(3)Crossing pole

Standard tension on crossing poles in fault conditions that conductors are not broken and lightning conductors are broken shall be equal to the total of the maximum tensions of each inlightn conductor.

(4)Pole in large overcrossing span

1)In the fault condition that single conductor hung by suspension being set on support poles of overhead power lines at large overcrossing span are broken, tension shall be equal to the total of tension of conductors calculated in climate conditions stipulated in article128 in Technical RegulationVol.1 and this Guideline.

2)The tension along the route of overhead power lines with conductors or lightning conductors hung by pulleys in fault conditions shall be as below.

-20 kN: single conductor in one phase

-35 kN: two conductors in one phase

-50 kN: Three conductors in one phase

3)Poles with one circuit shall be calculated in the fault condition that conductors of one phase are broken. Poles with twocircuits shall be calculated in the fault condition that conductors of two phases are broken and lightning conductors are not broken.

4)Standard tension acting on poles in the fault condition that conductors are not broken and

lightning conductors fixedby strain set are broken shall be equal to total of the maximum tensions of each lightning conductor.

5) Anchor poles with one circuit and dead end poles in large overcrossing span shall be calculated in fault condition that conductors in one phase are rokenb. Anchor poles with multiple circuits

shall be calculated in fault condition that conductors in two phases are broken and lightning conductors are not broken.

Article 259. Material of Poles

Poles of overhead power lines shall be the ones stipulated in this article in Technical RegulationVol.1.

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Article 260. Buried Portion of Poles

The depth of poles buried in the ground must be calculatedappropriately according to the topographical and geological conditions of the pole locationas well asphysical and mechanical characteristics of the pole.

Article 261. Confirmation for Anchor Poles

1.Requirement for anchor pole

(1)Installation conditions of conductors and lightning conductors of overhead power lines with voltage exceeding 1kV for checking shall be as below.

-Conductors of one circuit areonly installed at one side of a span and lightningconductors are not installed.

-Conductors are not installed and lightning conductors are only installed at one side of a span.

(2)Climate conditions during the check for anchor poles shall follow theontentsc in article 128 in Technical Regulation and this Guideline.

(3)For installation works such as pole erection or installation of conductors or lightning conductors of overhead power lines with voltage exceeding1kV, if necessary, temporary enhancement of parts of pole and temporary guys are permitted to be used.

2.Special requirements for anchor pole of overhead power lines with voltage of 500kV.

(1)Installation conditions of conductors and lightning conductors for checking shall be as below.

1) All conductors and lightning conductors are installed at one side of spans, and none of them are installed at the opposite side of spans. The tension of conductors and lightning conductors which have already installed at one side of spans shall be equal towot -thirds of the maximum tension in the climate condition that air temperature is °C15 (T=15°C) and wind pressure is 70N/m2 (q=70N/m2). If poles and all parts are tightly fixed to foundations, their condition shall meet Technical Regulation on the condition that temporary guys are not used.

2)All conductors on poles at one side of the span have already installed with any order, procedure and number of them when lightning conductors are not installed yet.

3)All lightning conductors on poles at one side ofthe span have already installed with any order, procedure and number of them when conductors are not installed yet.

(2)In installation works such as pole erection or installation of conductors or lightning conductors, if necessary, temporary enhancementof parts of pole and temporary guys are permitted to be used.

Article 262. Confirmation for Arms and Support Bars

1. Standard loads of accessories and workers with installing tools

Standard loads of accessories and workers with installing tools shall be the values thein following table, and other loads shall depend on the design values and the specification values of each structure.

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