UPS and power restoration post-blackout

[Newsome]

I have read that a UPS will prevent damage to computers when electrical power is restored after a power outage, while a surge protector will not.

1) Is this true?
2) If so, why?
3) If so, what value does a surge protector have?

 

[Zero82z]

It's sort of true but not really. A UPS will switch to battery mode for any devices connected to it when the mains go out, so when they come back on it will transition back to mains power after any power surges that might occur. However, a good surge protector should have no trouble protecting any attached devices either. And if there isn't a surge when the power comes back on, the PC has nothing to worry about altogether.

 

[Surly73]

I have read that a UPS will prevent damage to computers when electrical power is restored after a power outage, while a surge protector will not.

1) Is this true?
2) If so, why?
3) If so, what value does a surge protector have?

I find a lot of utility outages have transitions which occur at the magic "worst possible timing". To me that's about 0.5 second. Often when power goes out it'll go out for 0.5s, then maybe again, then maybe go black. I've had utility power come back in a fashion where it actually goes on and off a couple of times as they're manually effecting a repair.

In these cases a UPS is "on the job". My SmartUPS is configured to not return to utility power unless it is clean for 60s IIRC, regardless of whether it is shut down or still running on battery. Surge protectors don't do that.

 

[DanNeely]

Surly73: Is that a setting available in powerchute personal? If so, where?

 

[Surly73]

Surly73: Is that a setting available in powerchute personal? If so, where?

Not sure. My UPS is controlled by my server running linux, and I use apcupsd for syncing with any other machines on the same UPS.

It can be programmed into the UPS itself via serial cable, or presumably powerchute.

Beware that there are some units branded as SmartUPS that are a "lower level" of SmartUPS (stepped-square wave instead of true sine wave etc...) I'm not sure how that may affect the feature availability.

 

[Newsome]

Thanks for the replies. I just want to confirm this: there is a consensus that a quality surge protector will save a computer from post-blackout/brownout power spikes, as well as from lightening strikes?

 

[Surly73]

Thanks for the replies. I just want to confirm this: there is a consensus that a quality surge protector will save a computer from post-blackout/brownout power spikes, as well as from lightening strikes?

I don't think a single person responded that it would, so how would that be remotely close to a consensus?

The key thing to understand is that power transitions and brown outs can also damage components even though there was no spike or overvoltage condition which would have been clamped by a suppressor. Turning a computer on-and-off 10 times in 2 seconds isn't good for it either, and that might be the straw that breaks it, or scrambles your data, or....

If you want to be sure, get a UPS.

 

[Zero82z]

Thanks for the replies. I just want to confirm this: there is a consensus that a quality surge protector will save a computer from post-blackout/brownout power spikes, as well as from lightening strikes?

Surge protectors will protect only from power surges. A good line-interactive UPS will protect the computer from other irregular power conditions as well, such as brownouts, sags, irregular waveforms (if the UPS has any line conditioner circuitry built in as many better models do), etc. Whether or not you should get a UPS really depends on the overall quality of power that you receive where your computer is attached.