This test is performed only to confirm tensile strength of aluminum wires used for conductor in electric power cables. This test is significantly performed on conductor material to judge the strength of this material. A cable conductor is often subjected to pull from one end during laying, installing and manufacturing hence it should be strong enough to tolerate the pulling force as well. Hence it becomes necessary to ensure that the conductor material has sufficient tensile strength.
Apparatus required for Tensile Test
- Tensile Testing Machine: An automatic machine, with two end grips properly designed to hold the conductor with sufficient strength so that the conductor cannot slid by any means during the test. The machine should have sufficient capacity to apply required tension during test.
- Plane Faced Micrometer which can able to measure accurately even 0.01 mm variation. This is used to measure the diameter of the specimen conductor.
- Suitable Scale with least scale division 1 mm to measure length of the specimen conductor.
- Weighing Balance with sensitivity of 0.01g to measure mass of the specimen.
Method of Tensile Test of Conductors
A specimen of conductor with length little bit longer than gauge length (gauge length is the length of the specimen on which test is carried out) is first taken. To be careful that the minimum length of the entire specimen shall be such that it should have extra length at two ends after its gauge length for holding the same by grips of tensile testing machine. No pre-conditioning of the specimen is required for Tensile test.
Procedure of Tensile Test of Conductors
Before the test is conducted the diameter of the specimen is measured by plane faced micrometer and recorded. In case of shaped solidal conductor, the mass and length of specimen are determined by weigh balance ans measuring scale respectively. Now the test specimen is fixed and fitted in-between the jaws of the machine by means of grips. The load is applied to the specimen and it is increased gradually and uniformly. The rate of separation of jaws of the machine shall not be more than 100 mm per minute. When the Tensile test specimen is fractured, that breaking load is noted down from the dial of the tensile testing machine, and then tension strength is calculated.
Tabulation of Observations of Tensile Test of Conductors
|Diameter of Circular Wire in mm||Shaped Solidal Conductor||Cross Sectional Area in mm2||Breaking Load in N|
|Mass in g||Length in mm|
|Sample No||Aluminum Conductor Grade||Tensile Strength, N/mm2|
Conclution: Specimen meets/does not meet the requirements of specification.