Open fuse detection by neutral point shift
AssigneeToshiba International Corporation
InventorsToshiaki Oka, Mike C Daskalos
Life of this patent
Estimating the term…
Abstract
Systems and methods are shown for detecting a blown fuse in a three-phase line by comparing neutral points in the line before and after the fuses. Diode rectifier circuits may be used to compare the neutral points and generate a DC output voltage when neutral points are off from one another, and photocoupler circuits may provide electrical isolation when signaling a neutral point shift. The neutral points compared need not be on immediate sides of the fuses, so intermediate components may exist, and in some embodiments one of the compared points may be within a load connected to the three-phase line.
Claims16
A detection system, comprising:
- a comparator rectifier having input terminals connected to receive three-phase neutral points on opposite sides of fuses in a three-phase line;
- a comparator light-emitting diode, coupled to output terminals of the comparator rectifier;
- and
- an optical transmission circuit, coupled to the three-phase line on a load side of the fuses, wherein the optical transmission circuit includes an optical transmission circuit rectifier having input terminals coupled to at least two lines of the three-phase line, and output terminals coupled to an optical transmission circuit light-emitting diode.
A detection system, comprising:
- a comparator circuit rectifier having input terminals connected to receive three-phase neutral points on opposite sides of fuses in a three-phase line;
- a comparator circuit light-emitting diode, coupled to output terminals of the comparator circuit rectifier;
- an optical transmission circuit, coupled to the three-phase line on a load side of the fuses, wherein the optical transmission circuit includes an optical transmission circuit rectifier having input terminals coupled to at least two lines of the three-phase line, and output terminals coupled to an optical transmission circuit light-emitting diode;
- and
- a comparator circuit phototransistor, positioned to detect light emitted by the comparator circuit light-emitting diode, and having output terminals connected across terminals of the optical transmission circuit light-emitting diode.
A fuse monitoring method, comprising:
- detecting, by a comparison circuit, a three-phase neutral point shift between two positions on opposite sides of fuses in a three-phase line;
- wherein the comparison circuit includes an optical transmission circuit, coupled to the three-phase line on a load side of the fuses, wherein the optical transmission circuit includes an optical transmission circuit rectifier having input terminals coupled to at least two lines of the three-phase line, and output terminals coupled to an optical transmission circuit light-emitting diode;
- and
- determining, by a monitoring circuit, that one or more of the fuses has blown in response to detecting the neutral point shift, and signaling an alert of the blown fuse, wherein one of the positions is a neutral point on a DC bus of a rectifier load that is coupled to the three-phase line.
Dependencies are inferred from the claim text.