  We use a simple analytic model for the evolution of currents in
superconducting strings to estimate the strength of the `seed' magnetic fields
generated by these strings. This model is an extension of the evolution model
of Martins and Shellard depending on a parameter $f$ which characterizes the
importance of equilibration process in the evolution of the currents. For
GUT-scale strings, we find that a viable seed magnetic field for the galactic
dynamo can be generated if equilibration is weak. On the other hand,
electroweak-scale strings originate magnetic fields that are smaller than
required.
