Abstract: In a method for protecting lines, in which a reactor device for reactive power compensation is provided on an electrical line, a resonant current is measured on the line side of the reactor device by a first measuring device after an opening of a circuit breaker. A voltage is measured by a second measuring device after the opening of the circuit breaker. A current in the reactor device is calculated by an evaluation device on a basis of the measured voltage, and the calculated current is subtracted from the measured resonant current by the evaluation device in order to obtain a corrected current.

Abstract: In a method for protecting lines, in which a reactor device for reactive power compensation is provided on an electrical line, a resonant current is measured on the line side of the reactor device by a first measuring device after an opening of a circuit breaker. A voltage is measured by a second measuring device after the opening of the circuit breaker. A current in the reactor device is calculated by an evaluation device on a basis of the measured voltage, and the calculated current is subtracted from the measured resonant current by the evaluation device in order to obtain a corrected current.

Abstract: A first protective device monitors a first section of a power supply network for a symmetrical short-circuit and a second protective device monitors a second section for a symmetrical short-circuit. The second protective device is a reserve protective device, which emits a shut-off command to a power switch after a time lag when a symmetrical short-circuit in the first section is recognized. An oscillation recognition unit emits an oscillating signal which blocks the shutoff command if an oscillation in the power supply network has been recognized. External symmetrical short-circuits can be disconnected independently of an occurring oscillation, when the second protective device has recognized a symmetrical short-circuit in the first section, before the oscillation recognition unit recognizes an oscillation in the power supply network, the shut-off command is emitted independently of the presence of an oscillating signal if the lag time has elapsed.

Abstract: A first protective device monitors a first section of a power supply network for a symmetrical short-circuit and a second protective device monitors a second section for a symmetrical short-circuit. The second protective device is a reserve protective device, which emits a shut-off command to a power switch after a time lag when a symmetrical short-circuit in the first section is recognized. An oscillation recognition unit emits an oscillating signal which blocks the shutoff command if an oscillation in the power supply network has been recognized. External symmetrical short-circuits can be disconnected independently of an occurring oscillation, when the second protective device has recognized a symmetrical short-circuit in the first section, before the oscillation recognition unit recognizes an oscillation in the power supply network, the shut-off command is emitted independently of the presence of an oscillating signal if the lag time has elapsed.