HV three=phase power transformer short circuit protection appts. - uses current input circuit with input current transformers and measuring system for comparing transformer currents

摘要

A short-circuit protection appts. is for primary-side and secondary-side main current-transformer groups whose output currents are compared in a protection relay. The current input circuit comprises input current transformers and measuring system for comparing the currents of the input current transformers. The appts. is designed to protect against short-circuits and to eliminate the need for any intermediate current-transformers. Thus, the current input circuit for the discrete rotary switching groups is arranged so that it forms predetermined relationships, for comparison in the measuring system, from the interlinked transformer currents and/or difference magnitudes from the discrete transformer-phase currents and the transformer sum-current.