Frequency variation (imperfect 60Hz) from power-co?

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What in-house items can have problems if power is not maintained at 60Hz? I see some posts saying that not only are brown-outs and black-outs a problem, but frequency variation is a problem.

I would think that the most vulnerable devices are switching power-supplies (like in PCs), but would appreciate comments from the "non- electon-impaired".

-- Anonymous, March 12, 1999

Answers

Virtually all electronic equipment today will easily tolerate a variation from 50 to 60 Hz. The most sensitive item to frequency variation is (of all things) the 60Hz-driven clocks. The greater the deviation from 60Hz, the more incorrect their time will be. Aside from that .. the vast majority of electronics won't notice if you're feeding it 47 Hz, 55 Hz, 63 Hz .. etc. Conversely, if absolute synchronization isn't maintained on the grid at exactly the same frequency throughout .. the results would be catastrophic to the generating and/or distribution equipment.

Transformer-powered devices (not common in today's compact electronic gear) will tend to have the transformer run a bit warmer and the unit may exhibit a slight increase in "hum" in the audio/video. Output voltage from such power supplies may also tend to be slightly lower at 50Hz than at 60Hz.

Switching power supplies (as used in computers, newer stereos, etc.) are essentially frequency independent. They convert the incoming electricity to DC, chop it up into many little pieces, and (as needed) increase or decrease the voltage for use within the circuits.

Electronic gear is actually designed to accept a range of input frequency. In the USA, 60 Hz, is common .. while in other parts of the world .. you'll often find 50Hz being used. Subsequently, to allow the use in the widest possible range of environments, manufacturers try to make their equipment adaptable to as wide a range of input frequency as possible.

To be perfectly candid.. switching power supplies are FAR more susceptible to sudden voltage spikes than to frequency variation. Would be a good idea to turn off all sensitive electronic gear on December 31, 1999. Use a power strip or disconnect the gear from the wall outlet as some of the electronics often have some parts of them connected to power even with the unit in the "off" mode. An example would be anything with a remote control.

Sorry for the very non-technical explanation. To most folks, electronics in any form is black-magic and very complicated. If you wish a more detailed (albeit more complex) reply, feel free to contact me.

Dan

-- Anonymous, March 12, 1999


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