Electric Power Equipment Steel Power Pole

Electric Power Equipment Steel Power Pole

1.0 SCOPE

These specifications cover the design, engineering, manufacture, assembly, testing at manufacturer's works before dispatch of steel poles, cross arm assemblies, guy sets, danger plates, GI spike earthing sets for 33kV Single pole line, Suspension and Tension Fittings suitable for AAC Conductor for use on 3 phase, 50 Hz, solidly earthed 33kV Overhead lines.

• The design and workmanship shall be in accordance with the best engineering practices to ensure satisfactory performance throughout the service life.
• Any material and equipment not specifically stated in this specification but which are necessary for satisfactory operation of the equipment shall be deemed to be included unless specifically excluded and shall be supplied without any extra cost. Components having identical rating shall be interchangeable. The bidder has to furnish the testing facilities available at the manufacturer’s works.

2.0 STANDARDS

The steel poles, cross arm assemblies, cross brace assemblies and pole guard arms, guy sets, earthing sets etc. shall conform to the relevant IEC standards and any other equivalent neutrally acceptable International Standards (as amended upto date) mentioned below shall be applicable to the materials and processes used in the manufacturing of these equipment:

Whenever there is a difference in the Standards the most stringent criteria shall apply.

3.0 MATERIALS, CONSTRUCTIONAL DETAILS AND WORKMANSHIP

• Materials used in the manufacture of all the equipment shall be new and best quality and class most suitable for performance under the specified conditions.
• Steel used for manufacture of various equipment shall be in conformity with the general requirements relating to the supply of materials laid done in relevant international standards.
• The material analyzed in accordance with ISO 13520:2015 or other relevant international standard shall not show sulphur and phosphorous contents of more than 0.060% each.
• Equipment shall be well-finished, clean and free from harmful surface defects. Ends of steel poles, angle sections etc. shall be cut square and shall be straight.
• The bolts, nuts & pack washers and guy wire strand & cross arm guard wire shall be hot dip galvanized as per ISO 1461:2009(en) or other relevant international standards. The quality of zinc shall be at least Zn 98 grade specified in ISO 752:2004. The zinc coating shall be adherent, smooth, reasonably bright, continuous and free from such imperfections and flux, ash and dross, inclusions, flake and black spot, pimples, lumpiness and runs.
• The steel poles shall be hot dip galvanized with minimum 125 micron thickness of zinc coating and steel base plates with minimum 125 micron thickness of zinc coating generally as per ASTM A123 and tested as per relevant international standards..
• The articles shall withstand minimum 4 dips of one minute duration. The uniformity of galvanized coating shall be determined by the preece test as prescribed in ASTM A123.
• Suspension and Tension Fittings shall be made of Aluminum Alloy and all nuts and bolts shall be made of hot dip galvanized steel with minimum thickness of zinc coating of 85 micron as per ISO 10684:2004(en) Part XIII or other relevant international standards.

4.0 THE SPECIFIC TECHNICAL REQUIREMENTS OF VARIOUS EQUIPMENTS

4.1 Steel Poles

The purchaser may at its discretion furnish the design and fabrication data of one or more types of poles necessary for fabrication and testing of poles by the supplier or alternatively may ask the bidder to work out the optimum designs of poles and in that case submit detailed design calculations on ‘excel format’ for check and review by Employer.

Design of Poles shall be worked out and checked preferably as per ASCE Manual- 72 / SEI – 48- 05 or other relevant international standards. Poles shall be pre-drilled and supplied complete with pole top cap and base plate.

4.1.1 Specific Constructional Requirement

4.1.1.1 Poles shall be designed to withstand the worst possible combination of simultaneous loading of

• Lateral loads consisting of wind forces on conductors corresponding to wind spans, wind force on insulators, wind force on pole and maximum conductor tension.
• Vertical loads consisting of pole self-weight, weights of conductors, insulators, cross-arm, additional equipment, lineman and compressive force due to reaction of stays wherever applicable.

4.1.1.2 Steel poles for HV (33 kV), HV / LV mixed shall be worked out for the following types and applications:

• Contractor shall submit the detailed design & drawing of pole for each above said 33kV Transmission line for approval of Client and sample drawing showing dimension & configuration are enclosed.
• Poles shall satisfy the dimensional length and pole top loading requirements as per the design parameters listed in this specification. The dimensions across flats for top and bottom for all poles are listed in this specification/drawings as a preferred design to utilize one dimension for each type of pole length in so far as design & working load criteria is met.

4.1.1.5 Working Load

Working Load of a pole specified herein and defined as the load which when applied at 250 mm below top will induce the maximum permissible stress in the pole, shall be marked on each pole.

• The standard poles shall be suitable for the specified applications based on the design parameters given in Table 2, 3 & 4.
• A through hole of 14 mm diameter shall be provided in each pole at a height of 300 mm above the planting depth for earthing. The location of hole at a height of 300 mm shall be got approved from the Employer before manufacturing of the poles.

4.1.1.8 Base Plates

All poles shall be placed during erection on M-20, PCC pad of minimum thickness 75 mm and overall dimensions about 150 mm more than outside bottom dimension of the pole.

Alternatively; poles shall be supplied with separate square steel base plate fabricated from steel as per relevant Standards. Min. thickness of base plates shall not be less than 6 mm. Design calculations of thickness of steel base plates shall be submitted for check and review by Employer.

4.1.1.9 Guying

Poles for small angle locations (0 – 30°) shall be self-supporting. However; the poles for larger angle and terminal locations in un-inhabited areas can be provided with Anchor Guys placed the direction of the bi-sector of the angle at angle locations or length wise at the terminal locations. In the inhabited areas guys are not allowed; but Struts or two poles mechanically secured together can be deployed.

4.1.1.10 Design Parameters and Factor of Safety

Tolerances

i. Length

The tolerance on the length shall be as follows:

The finished pole shall not be out of straightness by more than 1/600 of its length.

The rolling and cutting tolerance for hot rolled steel products shall be in accordance with relevant international standards.