PSI - Issue 64

Jayathilake S. et al. / Procedia Structural Integrity 64 (2024) 137–144 Jayathilake S. et al. / Structural Integrity Procedia 00 (2024) 000–000

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The old aluminium conductor doesn’t show the required capacity according to the standard. Furthermore, new aluminium strands are also not complied with the standard at temperatures around 80°C and 100°C while steel strands comply with the AS3607 (1989). The conductor load is decreased with the increment of temperature for both aluminium and steel conductors although the rate of reduction is different. However, a 20% to 30% CBL reduction can be observed in the old aluminium cable with the new aluminium cable at room temperature. Furthermore, the new aluminium conductor also lost its tensile capacity by 10% when it is heated up to 100°C. However, the steel cable does not show much reduction in its breaking load, and it is around a 5% deviation from the new steel cable. Fig. 5 shows the variation of axial force in the ACSR at the selected wind events with the temperature changes. The experimental data on the breaking load is also incorporated in Fig. 5.

Fig. 5. ACSR conductor axial force at different wind velocities with the change of temperature.

As wind velocity increases, the axial force in the conductor also rises. Conversely, temperature increments lead to a gradual decrease in tension force within the conductor. Moreover, the CBL values for both conductors exceed the force requirements of all wind events. However, it is essential to compare the design requirement with the conductor load capacity specified in the Australian standard for OPDN. Accordingly, the conductor tension load should ensure safe operation, confirming that it remains under 50% of the CBL for the damage limit, as the conductor adheres to a linear stress-strain model. Additionally, the failure limit is 90% of CBL for the linear model (AS/NZS7000, 2016). Therefore, safety factors for both old and new conductors were computed for various wind events, with a check ensuring that the conductor tension remains under 50% of the CBL capacity. Fig. 6 illustrates the damage limit for both the existing new and old conductors, providing insight into the critical wind events for each. The safety factor is estimated as the ratio of conductor tension to 50% of CBL. The conductor tension is based on the standard while CBL was taken from experimental results.

Fig. 6. ACSR conductor safety factor due to wind at different temperature levels (a) New Conductor (b) Old Conductor.