Brown Outs: Causes & What To Do Next

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westom

18 posts

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#865121 24-Jul-2013 15:01

PaulBags: My electrial knowledge is lacking, would getting your own transformer be useful here?

If the transformer steps up AC voltage by ten percent during a brownout, then it also outputs 132 volts when 120 volts is normal. Transformers (that you can buy) do not adjust. Transformers that do adjust are already installed and maintained by the utility.

All voltages down to zero do not harm electronics. But that dimming indicates a potentially harmful voltage to motorized appliances. So the utility cuts off power to protect your motors.

How often do you lights dim to 50% intensity? And when - during what time or anomaly?

richms

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#865347 24-Jul-2013 19:56

Not quite true. Operating below design minimum voltage will mean increased currents which may exceed what things are designed for.
Also the switchmode power supply might end up driving the inductor/transformer into saturation if it is sized borderline for the load. Would be a pretty crap design to fail from under voltage vs a graceful shutdown.

Richard rich.ms

westom

18 posts

Geek

#865475 25-Jul-2013 00:38

richms: Not quite true. Operating below design minimum voltage will mean increased currents which may exceed what things are designed for.

Electronics are designed to operate even when incandescent bulbs dim to less than 50% intensity. Routine part of design is to operate everything at voltages even lower. To learn how low voltage is when it only turns off. All electronics work that way as even required by international design standards from long ago. It must work at all low voltages. Or it simply powers off.

In one standard, they are quite blunt. An expression in the entire low voltage regions and in all capital letters says, "No Damage Region". Low voltage does not damage any properly designed electronics. Low voltage is harmful to motorized appliances (ie refrigerator, furnace, washing machine).

If the inductor is so badly designed as to go into saturation, then a supply simply powers off.

Universal supplies operate on any voltage from 85 to 265 volts. Operating a universal supply (ie mobile phone charger, laptop computer) means it is damaged on 120 volt systems? That device, perfectly happy at 265 volts, is also perfectly happy when operating at 90 volts - are even worse brownout.

Damage from low voltage is a popular fairy tale that exists only when hearsay replaces well proven electrical concepts. Either it works just fine or powers off. Damage is often invented to sell a UPS.

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