Method for short-circuit protection of an electrical three-phase machine and a device for implementing the same

摘要

The method for short-circuit protection of an electrical three-phase machine, which is implemented by means of a device for short-circuit protection of the electrical three-phase machine is that phase currents in phases (4, 5, 6) of the winding of the stator (15) of the electrical three-phase machine (7) are formed with simultaneous generation of a magnetic flux through the windings (14) of the end parts of the coil groups (8 and 9, 10 and 11, 12 and 13) of each phase (4, 5, 6) of the winding of the stator (15), and the opposing current components are separated out from the phase currents by means of a corresponding unit (23). According to the invention, the opposing current components and the sum magnitude of the electromotive force are measured by measuring and comparison units (24, 25) simultaneously, which force is induced by the magnetic flux in operations which prevent short circuits in the winding of the stator (15) and is added by means of a device (16) for summation and conversion of the magnetic fluxes into electromotive force. If the current and electromotive force measured values increase above their maximum value, signals which initiate the switching off of the three-phase machine and correspond to the switching-off signal of said electrical three-phase machine are formed by forming devices (25, 29).