Circuit arrangement for the short-circuit protection of the externally-excited generator operation, which supplies power back into the supply network, of an electrical DC machine having compound excitation

摘要

The invention relates to a circuit arrangement for the short-circuit protection of the externally-excited operation of an electrical DC machine which supplies power back into the supply network and has compound excitation, having a series-excitation winding and having one or more controlled switching elements. …The essential feature of the invention is that the series-connected controlled switching elements and the series-excitation winding are connected to the terminals of the armature in such a manner that, when the controlled switching elements are closed, the internal voltage of the armature produces a current in the series-excitation winding whose direction is such that an excitation is produced in the series-excitation winding whose direction opposes the excitation of the external excitation winding, the controlled switching elements being controlled with the aid of sensors which are known per se. …Further advantageous embodiments of the circuit arrangement according to the invention can be characterised in that the controlled switching elements are formed by a thyristor, a thyristor which can be turned off (GTO) or a transistor.