Electricity: power supply or regulation systems – For reactive power control – Using impedance
Reexamination Certificate
2001-02-12
2001-09-04
Berhane, Adolf Deneke (Department: 2838)
Electricity: power supply or regulation systems
For reactive power control
Using impedance
C323S211000
Reexamination Certificate
active
06285169
ABSTRACT:
BACKGROUND OF THE INVENTION
It is often desirable to create power quality disturbances on alternating current systems. Such disturbances can be used, for example, to test the immunity of newly designed systems. For example, the SEMI-F47 standard, published by the industry association Semiconductor Equipment and Materials International, and the associated SEMI-F42-0600 testing standard, require that all semiconductor manufacturing equipment tolerate voltage sags to 50% of nominal for 200 milliseconds, to 70% of nominal for 500 milliseconds, and to 80% of nominal for 1 second. Devices that generate such sags for testing purposes are known as sag generators.
Transformer-based sag generators are well-known in the art. Grady et al. in U.S. Pat. No. 5,886,429 and Rockfield et al. in U.S. Pat. No. 5,920,132 disclose typical transformer-based sag generators. However, sag generators must be brought to the test location, so a key requirement for sag generators is portability. Transformer-based sag generators are heavy and awkward to transport.
Amplifier-based sag generators are also well-known in the art. SEMI F42-0600 in its “Related Information 1—Sag Generators” section discusses sag generators that consist of a power amplifier connected to a signal generator. However, such sag generators by their nature require multiple power conversions from alternating current to direct current and back to alternating current, with each conversion having power losses. Most implementations require transformer isolation. For these reasons, amplifier-based sag generators are generally limited to low power applications, and are often even heavier and more awkward to transport than transformer-based sag generators of equivalent output power.
In a sag generator, it is desirable to provide computer-controlled depth and duration of a sag. It is also, in many cases, desirable to provide a computer-controlled envelope of the sag, i.e. to allow the sag depth to vary in a controlled way during the sag. And it is also desirable to provide computer control of the phase angle at which the sag commences.
Typically, sag generators are rated by their nominal voltage and their maximum continuous current, for example 480 volts and 100 amps. Typically, portability of a sag generator is limited when it weighs more than 100 pounds: it becomes difficult to check as luggage on an airplane, and it becomes difficult for an individual to transport and set up.
OBJECTS AND ADVANTAGES
It is an object of this invention to provide a sag generator that is light and portable for high power applications.
It is a further object of this invention to provide a sag generator that allows automatic control of the sag depth, sag duration, sag envelopes and sag phase angle.
Still further objects and advantages will become apparent from a consideration of the ensuing description and accompanying drawings.
REFERENCES:
patent: 4131938 (1978-12-01), Milberger et al.
patent: 5355295 (1994-10-01), Brennen
patent: 5532577 (1996-07-01), Doluca
patent: 5541808 (1996-07-01), Bastian
patent: 5886429 (1999-03-01), Grady et al.
patent: 5920132 (1999-07-01), Rockfield et al.
patent: 5990667 (1999-11-01), Degeneff et al.
patent: 6118676 (2000-09-01), Divan et al.
patent: 6215202 (2001-04-01), Luongo et al.
SEMI F47-0200,Specification for semiconductor processing equipment, Voltage sag immunity, SEMI (Semiconductor Equipment and Materials International, 805 East Middlefield Raod, Mountain View, CA 94043), Feb. 2000.
SEMI F42-0600,Test method for semiconductor processing equipment, voltage sag immunity, SEMI (Semiconductor Equipment and Materials International, 805 East Middlefield Raod, Mountain View, CA 94043), Jun. 2000.
Berhane Adolf Deneke
Power Standards Lab.
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