Microscopic Mechanism Of Electrical Impulse Protection At Pre-twisted Wire Ports
In the operation and maintenance of transmission lines, the electrical connection interface between the armor rod preformed and the conductor is often overlooked. When a power frequency short-circuit current flows through the overhead ground wire wound with preformed armour rod, the current density distribution at the contact point between the armor rods port and the conductor is extremely uneven. This current skin effect leads to a sharp local temperature rise at the contact point, with the highest temperature reaching several hundred degrees Celsius. The conductor material anneales under high temperature, its mechanical strength drops sharply, and it eventually breaks under tension.
Physical Nature of Port Discharge Phenomena
The electrical impact damage at the pre-stranded wire port originates from microscopic discharge behavior. By reproducing the operating conditions using a short-circuit impact current test platform, staff observed two types of discharge phenomena at the port:
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Spark discharge: Occurs in the air gap near the first row of contact points at the pre-stranded wire port. The discharge intensity depends on the current flowing through a single contact point between the ground wire and the pre-stranded wire.
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Arc discharge: When the contact condition is poor, the continuous arc thermal effect causes localized high temperatures at the port, leading to the deterioration of the mechanical properties of the overhead ground wire.
From Failure Analysis to Structural Optimization
Based on a deep understanding of the armor rods for acsr-port discharge phenomenon, researchers proposed a stepped port structure design. This structure, by altering the current path distribution characteristics, avoids concentrating heat generation bottlenecks on the same radial cross-section of the ground wire. Under the same short-circuit current conditions, the mechanical load-bearing capacity of the ground wire at the stepped port is significantly improved.
