# Conductor losses

Conductor losses result from Joule heating of electrical currents in the conductors of electrical machine windings.

Conductor losses $P_{cond}$ increase with the square of the current through the windings and in proportion to the electrical resistance of the conductors: $$P_{cond} = \frac{3}{2} R_{ph} \hat{I}^2,$$ where $R_{ph}$ is the phase resistance and $\hat{I}$ is the peak phase current. Keep in mind that the phase resistance is temperature dependent and that you need to provide an accurate estimate of the temperature of conductors in order to get an accurate estimate of the conductor loss.

Conductor losses, together with iron losses, determine the electrical energy efficiency of electrical machines. The efficiency can be improved by reducing the conductor loss. Conductor losses can mainly be reduced by reducing the phase resistance, i.e. by improving the winding technique in order to be able to increase the cross-sectional area of the conductors and thus the slot fill factor, or by using conductor materials with a high electrical conductivity (such as copper).