Dan, In my experience the hold-up time is that period of time where during a power outage the product continues to operate within specified limits. Of course the specified limits are determined as a part of the contractual agreement between the supplier and the user.
Some people like to specify this as number of lost cycles on the line or as a period of time beginning at one of 4 points on the sine. 0, 90, 180 and 270 degrees. Also there is always the question, "do you compound the issue by adding requirements for 50 Hz and low line operation?". Other questions that may be asked are how long does the product operate (hold-up) during a 80 or 50% power line sag. If you check with the IEEE, I believe the power quality people have white papers on this sort of thing. But beware, most of the time when you implement solutions for power line sag you are adding bulk capacitance on the input section of a power converter. This can backfire with extremely poor power factor ratings and extremely long bus discharge times both of which affect regulatory compliance, the first for line harmonics and the other for safety. Doug Powell, Compliance Engineer Advanced Energy Industries, Inc. Fort Collins, Colorado USA --------- This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to [email protected] with the single line: "unsubscribe emc-pstc" (without the quotes). For help, send mail to [email protected], [email protected], or [email protected] (the list administrators).
