Manufacturing

Being a trusted PSC Pole Manufacturer and Supplier, we offer a premium range that is made out of Pre-stressed Concrete for unmatched strength and durability. Made available in diverse lengths, the PSC Poles are manufactured using advanced techniques under the supervision of experienced personnel. Moreover, stringent testing is done to ensure the best quality in terms of their strength and appearance.

PSC pole specification

PRESTRESSED CEMENT CONCRETE POLES ( F.O.S.2.5) FOR 22/11 KV AND LT LINES
(REC SPECIFICATION – 15/1979)

Scope

This Specification covers PSC poles with an overall length of 7.5M.and 9.0M suitable for use in overhead 22/11 KV and L.T. Power lines and double pole structures for 11/0.4 KV substations.

Applicable Standards

Except when they conflict with specific requirements in this Specification, the poles shall comply with the relevant provisions made in the following Indian Standard Specifications:

• IS: 1678-1978, Specification for prestressed concrete poles for overhead power, traction and telecommunication lines.
• IS: 2905-1966. methods of test for concrete poles for over- head power and telecommunication lines.
• IS: 7321-1974, Code of practice for selection, handing and erection of concrete poles for overhead power and telecommunication lines.

Terminology

• For the purpose of this standard, the following definitions shall apply
• Average Permanent Load
  That fraction of the working load which may be considered of long duration over a period of one year.
• Load Factor
  The ratio of ultimate transverse load to the transverse load at first crack.
• Transverse
  The direction of the line bisecting the angle contained by the conductor at the pole. In the case of a straight run, this will be normal to the run of the line.
• Transverse Load at First Crack
  For design, the transverse load at first crack shall be taken as not less than the value of the working load,
• Working load
  The maximum load in the transverse direction, that is ever likely to occur, including the wind pressure on the pole. This load is assume to act at a point 600 mm below the top with the butt end of the pole planted to the required depth as intended in the design.
• Ultimate Failure
  The conditions existing when the pole ceases to sustain a load increment owing to either crushing of concrete, or snapping of the prestressing tend on or permanent stretching of the steel in any part of the pole.
• Ultimate Transverse Load
  The load at which failure occurs when it is applied at a point 600 mm below the top and perpendicular to the axis of the pole along the transverse direction with the butt and of the pole planted to he required depth as intended in the design.

MATERIALS

• Cement:
  The cement used in the manufacture of priestesses concrete poles shall be ordinary or rapid hardening Portland cement conforming to IS: 269 – 1976 (Specification for ordinary and low heat Portland cement) or IS: 8041. E-1978 ( Specification for rapid hardening Portland cement)
• Aggregates:
  Aggregates used for the manufacture of pre-stressed concrete poles shall conform to IS: 383-1970 (Specification for coarse and fine aggregates from natural sources for concrete). The nominal maximum size of aggregates shall in no case exceed 12mm.
• Water:
  Water should be free from chlorides, sulphates, other salts and organic matter. Potable water will be generally suitable.
• Admixtures:
  Admixtures should not contain calcium chloride or other chlorides and salts which are likely to promote corrosion of pre-stressing steel.
• Pre-stressing Steel
  The pre-stressing steel wires, including those used as unmentioned wires should conform to IS:1785( Part-I)-1966 ( Specification for plain hard –drawn steel wire for prestessed concrete. Part-I cold drawn stress relieved wire), IS:1785(Part-Ii)-1967( Specification for plain hard-drawn steel wire). or IS:6003-1970 ( Specification for indented wire for pre-stressed concrete). The type designs given are for plain wires of 4mm diameter with a guaranteed ultimate strength of 175Kg/mm².
• The concrete mix shall be designed to the requirements laid down for controlled concrete (also called design mix concrete) in IS:1343 – 1980 (Code of practice for prestressed concrete) and IS:456-1978 (Code of practice for plain and reinforced concrete), subject to the following special conditions,
  • Minimum works cube strength at 28 days should be at least 420 Kg/cm².
  • The concrete strength at transfer should be at least 210Kg/cm².
  • The mix should contain at least 380 Kg. of cement per cubic meter of concrete.
  • The mix should contain as low a water content as is consistent with adequate workability. If it becomes necessary to add water to increase the workability, the cement content also should be raised in such a way that the original value of water cement ratio is maintained.

Design Requirements

The poles shall be designed for the following requirements.

• The poles shall be planted directly in the ground with a planting depth of 1.5 meters.
• The working load on the poles should correspond to those that are likely to come on the pole during their service life Designs given are for 140 Kg. and 200Kg. Applied at 0.6 M from top.
• The factor of safety for all these poles shall not be less than 2.5.
• The average permanent load should be 40% of the working load.
• The F.O.S against first crack load shall be 1.0.
• At average permanent load, permissible tensile stress in concrete shall be 30 Kg/cm².
• At the design value of first crack load, the modulus of rupture shall not exceed 55.2Kg/cm² for M 420 concrete.
• The ultimate moment capacity in the longitudinal direction should be at least one fourth of that in the transverse direction.
• The maximum compressive stress in concrete at the time of transfer of prestress should not exceed 0.6 times the cube strength.
• The concrete strength at transfer shall not be less than half the 28 days strength ensured in the design.i.e.420x 0.5= 210 Kg/cm².

For model check calculations on the design of poles, a reference may be made to the 3 REC ”Manual of Manufacturing of solid PCC poles, Part- I - Design Aspects”

Dimensions and Reinforcements

The cross – sectional dimensions and the details of pore stressing wire should conform to the particulars.

The Provisions of holes for fixing cross-arms and other fixtures should conform to the REC standards referred to in clause 4 of this specification and in accordance with the construction practices adopted by the State Electricity Boards.