Opgw Stringing y5j4z

PROJECT: INTERCONNECTION OF THE ELECTRICAL NETWORK BETWEEN LIBYA AND TUNISIA OVER HEAD HIGH VOLTAGE 225kV LINES IN TUNISIA CONTRACT NO. : MARCHE No I 20A 5020 PROPOSED METHODOLOGY OF OPGW STRINGING

1.0

INTRODUCTION: This document is issued as supplemental to the document already issued for conductor stringing method. Tension stringing method shall be adopted to install OPGW as well.

2.0

SCOPE: Scope of this write up shall address the areas not covered in the conductor stringing method statement. Otherwise the overall aspects of the stringing has been already discussed.

3.0

METHODOLOGY: By and large the OPGW also will be pulled in the same manner as that of conductor. However, in consideration of the down lead along tower leg from peak to t box this method shall slightly be modified in such a way that the running out cable from tensioner is routed inside the tower frame. This shall be decided after finalisation of OPGW pulling chart (drum chart) and taking into the construction of particular structure, sheave suitability for this purpose, other site conditions etc.

4.0

5.0

PROTECTION: 4.1

The machines shall be adequately anchored to ensure stability throughout pulling.

4.2

This machines and running cable shall be grounded as in the case of conductor stringing.

4.3

Possession necessary permits wherever applicable.

IMPORTANT CHECK POINTS: Special care will be given top ensure compatibility of following check points:

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5.1

5.2

5.3

5.4

SHEAVES (Rollers): a)

To ensure the grooves are free from nicks and scratches.

b)

To ensure free running wheels (suitably well greased bearings)

c)

To ensure all locking pins, nuts etc. in order and perfect.

PULLER a)

To ensure dynamometer is in order and functions.

b)

To ensure it is positioned as far as possible in line with pulling axis or to a maximum deviation of 100.

TENSIONER: a)

To ensure the machine is positioned in similar way of puller position.

b)

To ensure the used groove are free of nicks, cuts, soil etc.

c)

To ensure minimum distance of 20 metres maintained between Tensioner and Drums.

d)

To ensure the cable is received in right direction around bull wheel.

ENTRY & EXIT RUNNING POINTS: Specific care should be given to ensure sheaves are suitably attached at entry and exit points atop towers and run- through angle points to avoid bird caging.

5.5

UPLIFT ROLLERS OR HOLD DOWN BLOCKS: Wherever uplift is likely to occur during pulling due to higher tension / weight, ration uplift rollers or hold down blocks shall be used to counter this problem.

5.6

DOCUMENTS: To ensure following stringing documents are available with Stringing Supervisor: a)

Stringing Chart (Sag-Tension) for OPGW

b)

OPGW Drum Schedule.

c)

Maximum permissible pulling value of OPGW. 2

5.7 6.0

COMMUNICATION: Walkie – Talkies.

STEP BY STEP PROCEDURE OF INSTALLATION: 6.1

Anti-twisting braided pilot wires of 10 mm or above shall be used to pull OPGW.

6.2

Maximum permissible pulling tension will be present in the puller if such facilities are available in the machine. In case no such facility available, the operator shall maintain a constant watch on the dial gauge.

6.3

Use of pulling socks, swivel connector between socks and pilot wire shall be in the same way as that of conductor pulling.

6.4

Once communication is established between Puller and Tensioner ends and clearance given by Tensioner end, pulling shall start at very slow speed and gradually increase up to 3 to 3.5 km/ hour until the required length is pulled out. Subject to the provision in Drum usage chart, the remaining length of OPGW can be pulled out and cut away so that the most stressed part of the cable is excluded from permanent installation. Band clamps wherever supplied at ends of cable shall stay in position until pulling gets over.

6.5

Once pulling is completed, sagging, clipping etc. shall be done in similar way of conductor installation. Self Gripping (or) Bolted conductor clamps shall be used in conjunction with pull-lift to accomplish sagging. OPGW shall be guided along the tower leg as per approved drawings and clamped up to t box, leaving approximately 5-8 mtrs. cable coiled and end to facilitate splicing and testing.

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