The performance of a cylindrical-rotor generator, without damper windings, connected to an uncontrolled bridge-rectifier load, is considered. Assuming constant field-flux linkages, equations are derived which enable the performance of generators to be predicted. The commutation angle, the displacement angle and the field-current perturbation are the quantities which characterise generators with rectifier loads. Modification of the equations for a controlled bridge is discussed. The equations are supported by some practical tests on a laboratory machine.