Abstract: Method and equipment for transferring energy to or from a direct-current superconducting field coil to change the magnetic field generated by the coil in which a second direct-current superconducting coil is used as a storage coil, and energy transfer between the field coil and the storage coil is effected automatically in dependence upon a control programe. Preferably, the control programe acts upon a variable transformer which is coupled by respective rectifier/inverters to the field and storage coils and also serves for initial supply of energy to the coils.