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 Title: |
US5300924:
Harmonic measuring instrument for AC power systems with a time-based threshold means
[ Derwent Title ]
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| Country: |
US United States of America
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| Inventor: |
McEachern, Alexander; Oakland, CA
Nicholson, Jamie; Foster City, CA
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| Assignee: |
Basic Measuring Instruments, Foster City, CA
other patents from BASIC MEASURING INSTRUMENTS (54465) (approx. 22)
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| Published / Filed: |
1994-04-05
/ 1992-08-21
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| Application Number: |
US1992000934355
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| IPC Code: |
Advanced:
G01R 23/165;
Core:
more...
IPC-7:
G08B 21/00;
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| U.S. Class: |
Current:
340/660;
324/107;
340/658;
340/661;
702/064;
Original:
340/660;
340/661;
340/658;
364/483;
324/107;
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| Field of Search: |
340/664,660,661,662,658,657
364/483-484
361/113
324/623,107-142
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| Priority Number: |
| 1992-08-21 |
US1992000934355 |
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| Abstract: |
An instrument for measuring voltage harmonics and current harmonics on AC (alternating current) power systems. The instrument includes the ability to determine when threshold limits have been exceeded for harmonics. The instrument also includes timing thresholds whose inputs are activated when the harmonic thresholds are exceeded. A single harmonic threshold is applied to measurements from multiple phases on poly-phase systems by comparing the square rot of the sum of the squares of measurements from each phase to the harmonic threshold. Three indicators show when voltage harmonic limits are exceeded, current harmonics limits are exceeded, or both voltage and current harmonic limits are exceeded simultaneously.
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| Attorney, Agent or Firm: |
Haverstock, Medlen & Carroll ;
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| Primary / Asst. Examiners: |
Hofsass, Jeffery A.;
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| Maintenance Status: |
E1 Expired Check current status
CC Certificate of Correction issued
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| INPADOC Legal Status: |
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| Family: |
None
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First Claim:
Show all 24 claims |
We claim:
1. An apparatus for measuring voltage harmonics and current harmonics on an alternating current power system comprising:
- a. means for sensing a predetermined harmonic voltage parameter and a predetermined harmonic current parameter coupled to the alternating current power system;
- b. means for comparing the harmonic voltage parameter to a predetermined voltage threshold and for comparing the harmonic current parameter to a predetermined current threshold coupled to the means for sensing;
- c. means for calculating a first time parameter during which the predetermined voltage threshold was exceeded by the harmonic voltage parameter and a second time parameter during which the predetermined current threshold was exceeded by the harmonic current parameter coupled to the means for comparing; and
- d. means for indicating when either the first time parameter or the second time parameter exceed a predetermined time threshold.
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| Background / Summary: |
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| Drawing Descriptions: |
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| Description: |
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| Forward References: |
Show 12 U.S. patent(s) that reference this one
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