LUKE YUEN-MING YU
Engineers in Pasadena, CA

5790356, Aug 4, 1998

Oct 4, 1996

8/720948

Gerald W. Bottrell - La Crescenta CA
Luke Y. Yu - San Marino CA

H02H 300

361 35

A conversion of a three-phase, four-wire power system to divert all zero-sequence current from the power system grounded-neutral source transformer and its phase and neutral conductors. A zero-sequence filter transformer such as a zig-zag transformer is installed, and the system neutral conductor and ground point are relocated from the neutral terminal of the source transformer to that of the zero-sequence filter transformer. A protection scheme operates to trip a main circuit breaker for zero-sequence filter transformer overloads or short circuits. The source transformer and its neutral circuit are thereby protected from the ill effects of zero-sequence currents.

2003016, Aug 28, 2003

Sep 9, 2002

10/237281

Luke Yu - San Marino CA, US
Henry Yu - San Marino CA, US

H02J001/02

307/105000

A broad-spectrum harmonic filter is developed. This filter is to be connected in series ahead of the load which generates harmonics. This filter basically consists of 3 fixed elements, i.e. a series reactor and a shunt reactor in series with a capacitor. It can function to completely filter out 5harmonic current in 3 phase systems (or 3harmonic current in single phase systems) and to reduce other harmonic components by high percentages say, typically close to 70%. Thus the portions of various harmonics flowing toward the electrical power source can be held within acceptable limits. By adjusting these two reactors and the capacitor, a desirable and controllable filtering performance can be achieved. A satisfactory performance of the filter and the electrical system can be expected by use of this invented filter with only 3 major elements. A voltage compensator, a reactor of “negative value” is recommended to compensate for the harmonic voltage distortion across the series reactor (or the filter), if necessary, or to compensate for the voltage drops under power frequency operations.

2008012, Jun 5, 2008

Jul 27, 2004

10/901265

Luke Yu - San Marino CA, US
Henry Yu - San Marino CA, US

H02J 3/01

307105

A broad-spectrum harmonic filter is developed. This filter is to be connected in series ahead of the load which generates harmonics. This filter basically consists of 3 fixed elements, i.e. a series reactor and a shunt reactor in series with a capacitor. It can function to completely filter out 5th harmonic current in 3 phase systems (or 3rd harmonic current in single phase systems) and to reduce other harmonic components by high percentages say, typically close to 70%. Thus the portions of various harmonics flowing toward the electrical power source can be held within acceptable limits.

4772977, Sep 20, 1988

May 1, 1987

7/044721

Gerald W. Bottrell - La Crescenta CA
Luke Y. Yu - San Marino CA

FTS, Inc. - Downey CA

H02H 708

361 23

A system for use with electrical machines allows fast transfers to be made from one power source to another or fast reconnections to be made to a momentarily interrupted power source without subjecting the machines to unsafe voltage levels. The system short circuits the electrical machines to bring their residual voltage down quickly to a level at which the machines may be safely connected to a power source, and works with both induction and synchronous machines. No interlocking devices are necessary to the system, thus further speeding up fast transfer while minimizing the effects of inadvertent direct short circuiting of the power source.