IEC 60888 Zinc-coated steel wires for stranded conductors tension, torsion wrapping test This standard applies to zinc-coated steel wires used in the construction and/or reinforcement of conductors for overhead power transmission purposes.

It is intended to cover all wires used in constructions where the individual wire diameters, including coating, are in the range of 1.25 mm to 5.50 mm.

Three grades of steel are included to reflect the needs of conductor users: regular steel, high strength steel and extra high strength steel.

Tensile test

The breaking load of the specimen shall be determined by means of a suitable tensile test-.ing machine. The load shall be applied gradually and the rate of separation of the jaws ofthe testing machine shall be not less than 25 mm per minute and not greater than 100 mmper minute.

In calculating the tensile stress from the measured breaking load, the diameter of thefinished wire before stressing shall be used.

Torsion test

One specimen shall be gripped at its ends in two vices with the distance between vicesequivalent to 100 times the nominal wire diameter, one of which shall be free to movelongitudinally during the test. A small tensile load, not exceeding 2 % of the breakingstrength of the wire, shall be applied to the sample during testing.

The specimen shall be twisted by causing one of the vices to revolve until fracture occursand the number of twists shall be indicated by a counter or other suitable device.

The rate of twisting shall not exceed 60 rev/min.