Method and apparatus for monitoring conductor currents for a fault current
AssigneeSiemens Aktiengesellschaft
InventorFritz Breimesser
Life of this patent
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Abstract
A method and apparatus for monitoring conductor currents for a fault current which changes the magnetic bias of a magnetic circuit in which the magnetization of the magnetic core is alternatingly reversed by sequences of magnetizing pulses and a determination made of the number of pulses up to which the pulse amplitude exceeds predetermined voltage reference value, with the change of this number of pulses used to derive an output signal.
Claims15
A method for monitoring conductor currents for a fault current which changes the magnetic bias of a magnetic circuit, having a secondary winding to which a capacitor and a tripping device are connected, comprising:
- (a) alternately reversing the magnetization of the magnetic core of the magnetic circuit in steps with sequences of magnetizing pulses;
- (b) determining the number of pulses within the pulse sequences up to which the pulse amplitude exceeds a preset voltage reference value at a predetermined sampling point within the pulses;
- and
- (c) deriving an output signal in response to a change in the number of pulses exceeding said preset reference valve.
In apparatus for monitoring conductor currents for a fault current which changes the magnetic bias of a magnetic circuit, having a secondary winding to which a capacitor and a tripping device are connected, by an electronic circuit shunted across the secondary winding and the capacitor, said electronic circuit including:
- (a) a pulse generator coupled to deliver to the secondary winding sequences of magnetizing pulses of predetermined number and with a direction which changes after each sequence;
- (b) an evaluation device coupled to detect the respective number of pulses within the pulse sequences up to which the pulse amplitude exceeds a predetermined voltage reference value at a predetermined sampling point within the pulse;
- (c) mean to derive an output signal from the change of said number of pulses;
- and
- (d) means for controlling said pulse generator, evaluation device and means to derive.
Dependencies are inferred from the claim text.