Peak Inverse Voltages in the Rectifier Excitation Systems of Synchronous Machines

A modern large ac generator draws excitation power from an ac exciter through a rectifier bridge. If the generator loses synchronism and slips with respect to the system the field current cannot reverse d the rectifier cells are subjected to inverse voltages. This situation has been modelled in the laboratory with a micro-machine and step-by-step calculations have been made which correlate with the laboratory tests. Calculated values using the parameters of a large machine are compared with measured values of inverse voltage.