SETT FOR DISTANSSELEKTIV KORTSLUTNINGSOVERVAKNING AV ELEKTRISKA LEDNINGAR OCH ANORDNING FOR GENOMFORANDE AV NEMNDA SETT

摘要

A method of, and apparatus for, the distance-selective monitoring of faults at electrical lines by means of a quadrilateral trigger or trip region. There are formed at least two reference signals of at least approximately the same phase and from each of these reference signals and the line voltage there is formed a respective difference signal. Each difference signal experiences a separate comparison with a related threshold phase angle in order to determine whether the monitored fault lies within or without the trip region.