Voltage-sag resistance of computer and semiconductor manufacturing systems


If anyone has had their computer crash due to very brief power flicker, website
you can sleep better knowing that there Information Technology Industry Council is working hard to keep you on-line. I started reading a book on power delivery and quality and have found this figure above, the CBEMA/ITIC curve. The idea is that power supplies and systems in “information technology” are designed to comply with certain voltage tolerances, or rather tolerate certain deviations from the normal 120Vac@60Hz (in the U.S.A.) for specified amounts of time. For example, this type of equipment is supposed to tolerate a total loss of power for one half of a cycle without interruption. Conversely, the same equipment is supposed to tolerate a voltage surge of 500% of the nominal value for 1% of a total cycle period.

After looking deeper, I also located a SEMI F47 power standard which applies to manufacturers of equipment and subsystems destined for semiconductor manufacturing. This standard is not as rigorous as the one above and is only specified for voltage sags. It can be seen that this type of equipment must be tolerant of a reduction of line voltage to 50% of nominal value for up to 0.2 seconds on a single phase system or on one phase to neutral for a three-phase system. A presentation covering updates to the SEMI F47 standard is available here.

voltage_tolerance.pdf )

( semi_standards.pdf )

( 4overviewofsemif47-0706.pdf )

( iticurv.pdf )

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