Abstract: A method of short-circuit protection of an electrical three-phase machine, realized in a short-circuit protection device for a three-phase electrical machine, provides that phase currents are formed in phases of the stator winding of a three-phase electrical machine and, concurrently, a magnetic flux is produced by the end loops of coil groups of each phase in the stator winding, and a reverse current is separated from phase currents by a reverse current discriminating unit. Afterwards, current measuring and comparing units simultaneously measure the reverse current and the total electromotive force, produced by the magnetic flux in conditions excluding short-circuits in the stator winding and added up by a means for summing and converting magnetic fluxes into the electromotive force. In case the measured magnitude of the current and the value of the electromotive force exceed the maximum, three-phase electrical machine disconnection signal shapers produced respective signals which cut out the machine.