- Annealing Test Definition: The annealing test is performed to ensure the durability and flexibility of wires and conductors during twisting and bending.
- Specimen Preparation: A specific gauge length of the conductor is used for the test, ensuring accurate results.
- Testing Equipment: A tensile testing machine, micrometer, and measuring scale are essential for conducting the annealing test.
- Elongation Measurement: The test measures the elongation percentage of the specimen after it fractures.
- Result Reporting: The results indicate if the specimen meets the specified elongation requirements.
This test is normally carried on annealed copper wires, aluminum wires for welding cables and solid conductors of electric power cables. The current carrier conductors of power cable is subjected to twist and bend during laying and installation hence it should be flexible enough to take any desired bending and twisting without breaking and cracking. Annealing test for wires and conductors is performed to confirm the durability of conductor during twisting and bending.
Process of annealing test for wires and conductors
A conductor specimen is selected for testing. It must be of a specified gauge length for accurate results. The total length includes the gauge length and extra lengths at both ends for holding in the tensile test machine.
A tensile testing machine is used, which is automatic and meets the test requirements. The machine must firmly grip the specimen. Additional tools include a plane-faced micrometer with 0.01 mm divisions and a measuring scale with 1 mm divisions. Only one specimen is needed, and no pre-conditioning is required. The specimen is fixed, and tensile stress is applied gradually until it fractures, with an elongation rate not exceeding 100 mm per minute.
The elongation is measured on the gauge length after the fractured ends have been fitted together. The elongation is expressed as a percentage of the original specimen gauge length. Main observation of annealing test for wires and conductors is that whether the specimen meets or does not meet the specified maximum allowed elongation. Plane Faced Micrometer with scale division at least 0.01 mm is used to measure the diameter of the specimen used in the test.
If L is the original length of the specimen and L’ is the total length after it fractures, then L’ is the sum of the two fractured parts. The percentage elongation is calculated as:
Tabulation of Observations of Annealing Test
| Diameter of Circular Wire in mm | Size of Shaped Solidal Conductor in mm2 | Original Gauge Length, L in mm | Length After Fracture, L’ in mm | Elongation (L’ – L) in mm |
| – | – | – | – | – |
| – | – | – | – | – |
Calculation
Where, L = original gauge length of specimen
and L’ = elongated length of specimen
Report
| Sample No | Diameter of Circular Wire | Size of Shaped Solidal Conductor | Elongation, percent | |
| Observed | Specified | |||
| – | – | – | – | – |
Conclution :
Specimen meets/does not meet the requirements of specification.
