Improved Electromagnetic Model for Steel-Cored Conductors

The core magnetization of steel-cored conductors can affect their alternating current resistance and the current distribution between their aluminum layers, depending on several aspects such as the current carried by the conductor, the number of aluminum layers, and the steel core magnetic properties. Electromagnetic models can consider these aspects when calculating the effects of the core magnetization and also be used to optimize the conductor's design in order to reduce losses. However, as the existing models represent the steel core in a simplified way, calculations may not be accurate for high currents and the design optimization is restricted to changes in the aluminum layers only. This work presents a new electromagnetic model for calculating the resistance and current distribution of steel-cored conductors, in which their core is appropriately represented. Results show good accuracy for a conductor with three and a single aluminum layer over the whole current range analyzed. It is also shown that the magnetic fields produced in the steel layers can play an important role in reducing the core magnetization and that it is possible to further reduce losses by optimizing the core design.