Electric power conversion systems – Phase conversion without intermediate conversion to d.c. – By induction-type converter
Patent
1992-04-20
1996-07-16
Sterrett, Jeffrey L.
Electric power conversion systems
Phase conversion without intermediate conversion to d.c.
By induction-type converter
363156, 323215, 323361, H02M 510
Patent
active
055373097
ABSTRACT:
A method and apparatus for providing a source of alternating current electrical power to a plurality of loads in an office environment, including a plurality of non-linear loads which draw power for only a portion of the alternating current cycle, includes an input source of electrical power to a primary side of a power transforming device which provides an output at its secondary side which comprises at least two phases and a shared neutral. The plurality of loads are evenly distributed between each phase of the output power source and the shared neutral so as to reduce by current cancellation the current which would otherwise flow in the shared neutral conductor due to the presence of the non-linear loads. In one embodiment, each of six output phase is separated from the other by 120 electrical degrees, and the fourth, fifth and sixth phases are separated from the first, second and third phases, respectively, by 180 electrical degrees. In another embodiment, two sets of six phases are provided, with each of the phases in the first set shifted, relative to respective phases of the second set, so as to reduce variations in the level of instantaneous power drawn from the input source which would otherwise occur due to the presence of the non-linear loads. Additional embodiments incorporate autotransformers which may be advantageous in smaller or preexisting installations. Benefits of the invention include lower ground to neutral noise, reduced transmission losses, more accurate power measurement by induction watt-hour meters, and fewer instances of neutral current overload.
REFERENCES:
patent: 412932 (1889-10-01), Shallenberger
patent: 771786 (1904-10-01), Lunt
patent: 815765 (1906-03-01), Troy
patent: 1082561 (1913-12-01), Schwarz
patent: 1175320 (1916-03-01), Varley
patent: 1188145 (1916-06-01), Blume
patent: 1480712 (1924-01-01), Fortescue
patent: 1727834 (1929-09-01), Kubler
patent: 2024746 (1935-12-01), Rose et al.
patent: 2085123 (1937-06-01), Rose
patent: 2128055 (1938-08-01), Rose
patent: 2166900 (1939-07-01), Bohn et al.
patent: 2306226 (1942-12-01), Schrage
patent: 2307527 (1943-01-01), Maslin et al.
patent: 2330088 (1943-09-01), St. Palley
patent: 2632878 (1953-03-01), Uhlmann
patent: 2634396 (1953-04-01), Solomon
patent: 3211914 (1965-10-01), Anderson
patent: 3942032 (1976-03-01), Casazza
patent: 4053820 (1977-10-01), Peterson et al.
patent: 4106089 (1978-08-01), Fettinger
patent: 4689735 (1987-08-01), Young
patent: 4695933 (1987-09-01), Nguyen et al.
patent: 4779181 (1988-10-01), Traver et al.
patent: 4849870 (1989-07-01), Heinrich
patent: 5046963 (1991-09-01), Kelly
patent: 5107410 (1992-04-01), Marsh et al.
"Nonlinear Loads Mean Trouble", Arthur Freund, Senior Editor, Electrical Construction & Maintenance, Mar. 1988.
"Double the Neutral and Derate the Transformer-or Else?", Arthur Freund, Senior Editor, Electrical Construction & Maintenance, Dec. 1988.
"Harmonic Analyzer Helps Solve Power Problems", David Kreiss, Electrical Construction & Maintenance, Mar. 1989.
Marsh John K.
Zemen, Jr. Russell E.
Group Dekko International
Sterrett Jeffrey L.
LandOfFree
Multi-phase and shifted phase power distribution systems does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Multi-phase and shifted phase power distribution systems, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Multi-phase and shifted phase power distribution systems will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1789524