I believe the answer to be "it depends"
The reason is that the appliance manufacturer has to meet various national electrical safety standards before he can place his goods on the market. The type approval for domestic electrical safety will include operation on 90% and 110% of the 50/60Hz supply. Those tests do not include survival of overvoltage or undervoltage beyond the requirement that the product remain safe. It need not work after the over or undervoltage. Remember this is the domestic environment and line conditions are much more benign than in the telecoms and power industries. I believe there is a figure of 600V that describes the maximum likley transient surge voltage on a domestic power outlet. One of the differences between the 'Maytag' and the 'no name' brands is what happens with over and undervoltage. Long term reliability differences will arise depending on the hardware 'over-build' for adverse conditions. These are not things the typical consumer understands and so cannot even be made public in the limited specififcations published. To summarise effects: low voltage: harmful to electric motors and some switching power supplies which may include TV sets and home computers. When input voltage drop causes input current to rise then expect overheating of power supply parts, fuses blow, motor insulation overheating and coil winding burn-out; may affect microwave cookers too. high voltage: harmful to lighting and thermally limited circuits. When input voltage rise cause input current to fall then the reverse of the effects above will be true. But some devices that are voltage sensitive may overspeed for example. Safety insulation is usually rated with a large margin above normal conditions, lets say 1000V breakdown voltage on a 120V circuit. When over voltage occurs, say to 180V, then the insulation safety margin is still big enough to protect most applications. For these reasons the consequences of under and over voltage on the full spectrum of domestic electrical machines are not in agreement with 'common sense' which says too much voltage will be harmfull, too little voltage not a problem. In fact the opposite is true for many types of domestic electrical hardware. In my semi rural home 50 miles NW of NYC I have the normal 120V 60Hz domestic supply. The well water pump starts automatically and pulls a lot of current. Inside the house the tungsten lighting brightens about 30% for half a second everytime the pump turns on. I've only been there two years but in that time the only electrical failure has been a cheap Radio Shack telephone answering device. Two PC terminals, two TVs, the fridge, the lights, the audio system have all withstood the 'pump on' surge without failure, so far. Does this help? Best Regards Ted Rook, Console Engineering, ext 4659 Please note our new location and phone numbers: Crest Audio Inc, 16-00 Pollitt Drive Fair Lawn, NJ 07410 USA 201 475 4600 telephone receptionist, 8.30 - 5 pm EST. 201 475 4659 direct line w/voice mail, 24 hrs. 201 475 4677 fax, 24 hrs. ------------------------------------------- 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"
