Electricity: measuring and testing – Measuring – testing – or sensing electricity – per se – With coupling means
Reexamination Certificate
2000-11-21
2002-09-24
Le, N. (Department: 2858)
Electricity: measuring and testing
Measuring, testing, or sensing electricity, per se
With coupling means
Reexamination Certificate
active
06456061
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates generally to sensing electrical current on a current path, and more specifically, to calibrating a current sensor by trimming target surfaces along the current path.
Many products require sensing electrical current in a current path to provide the necessary input for electronic control devices. The accuracy of the current sensing and current measurements may be affected by variations in resistance at the current path, variations at jointed areas, even material changes in grade and density of the conductor material. The sensor itself may introduce errors contributing to inaccuracies. For example, when using a current transformer (CT), inherent variations from one CT to another can affect the transformer's accuracy. Consequently, variations with respect to different CTs necessitate setting tolerance parameters to accommodate these variations.
In circuit breaker applications, the current is measured by installing a CT that is directly affected by the current flow through the conductor. The electrical current may be measured by passing only a portion of the current through the CT or by passing all of the current through the CT. A portion of the current may be measured as representative of the whole current. To measure a portion of the current, a current bridge or current divider may be used.
Current dividers and current bridges enable one to determine the magnitude of a large current by dividing the current into parallel flows, and measuring only a fraction of the total current, i.e., by measuring the current through one branch of the conductor. The current measurement is then divided by the fraction of current through that conductor branch to determine the total current in all parallel conductor branches.
Current dividers are a useful means of measuring a large current or current through large conductors, however they have not greatly overcome the inherent inaccuracies of current sensors discussed above.
Therefore, it is desirable to calibrate current sensors to overcome the manufacturing variations in conductors, sensors, and associated electronics.
SUMMARY OF THE INVENTION
The above discussed and other drawbacks and deficiencies are overcome or alleviated by a method for calibrating a current sensor having a conductor that comprises at least two conductor branches electrically connected in parallel. The method comprises passing a predetermined electrical current through the conductor, measuring a fraction of the current that passes through a measured conductor branch, which is one of the two conductor branches, comparing the measured current against a predetermined target current, trimming a calibrating conductor, which is one of the at least two conductor branches, the trimming taking place when said measured current and said predetermined target current are not equal.
REFERENCES:
patent: 4182982 (1980-01-01), Wolf et al.
patent: 4492919 (1985-01-01), Milkovic
patent: 4496932 (1985-01-01), Halder
patent: 4749940 (1988-06-01), Bullock
patent: 4939451 (1990-07-01), Baran et al.
patent: 5066904 (1991-11-01), Bullock
patent: 5841272 (1998-11-01), Smith et al.
Attarian Farshid
Criniti Joseph
Figueroa Alberto Anibal
Larranaga Javier Ignacio
Cantor & Colburn LLP
General Electric Company
LeRoux Etienne P
LandOfFree
Calibrated current sensor does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Calibrated current sensor, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Calibrated current sensor will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2864635