Peter, You'll probably get no more than anecdotal feedback, so here's mine. Regarding undervoltages, I can think of nothing damaged by low voltage in itself, only its consequences. The primary cause is the need for some products to maintain its power output or speed. For a lowered voltage, you get an increased current.
For motors and transformers, this is a well studied problem and handled either by thermal overload protection or overcurrent protection. In switching supplies, you are likely to get overheating in the rectifiers, transformers or switch due to increased current. In the case of overvoltages, dielectric strength is the obvious concern. Breakdown of insulation in any component generally causes failure. Operating characteristics for almost all components regarding continuous and transient overvoltages are available. Of course linear loads will simply overheat with increased voltage. In magnetics, overvoltages will cause saturation and overcurrent. Most of these effects can be handled with the same overcurrent protection needed for undervoltages. There are several overvoltage situations which increase heat dissipation, for example approaching the operating point of MOVs and similar voltage limiting devices, or increasing the ripple current in filter capacitors. The impact on cases like these is best judged by test, and can be much harder to protect against since other operating parameters will be within normal limits. It is wise to routinely consider the steady state effects of up to two times rated voltage which can occasionally be found if a neutral opens in two or three phase mains sources. Bob Johnson ITE Safety ------------------------------------------- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: [email protected] with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: [email protected] Dave Heald: [email protected] For policy questions, send mail to: Richard Nute: [email protected] Jim Bacher: [email protected] All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on "browse" and then "emc-pstc mailing list"
