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Joules: How much difference does it make?

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metallicafan

[H]ard|DCer of the Month - May 2010
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I am looking at buying a UPS for my computers. Now the ones from Triplite that I am looking at have like 4 battery backup outlets, and 4 surge only outlets. In the documentation it states that the unit has something like 480 joules of surge protection. Is that enough? I understand what a joule is and how it works but how much "surge capacity" should the unit have? My little surge strip was advertised to have like 1000+ joules so it made me wonder if 480 joules wasnt a little low. Thanks.

Spectre - I read skimmed your FAQ, but didnt see anything on this subject. If the number of joules a surge unit is rated for is at all important many you could put some information on this in your FAQ.
 
It really doesn't make that much difference on a UPS because the transformer inside the UPS acts as a surge supressor and your power supply has a varistor on the primary side that should cut down variants.

The Joule rating is good for the pass-through side of the UPS, but I'd just as well use a power strip for the "surge only" devices.

Be more concerned with the unit having AVR (which I believe the Tripp-Lite Omni's do.)
 
Would it be OK to plug the UPS into a surge protector and then plug the surge protector into the wall? I only ask because I only have one wall outlet near my computers.

The battery backup outlets on the UPS are protected by the surge protector too are they not? Maybe I just misunderstood your reply.
 
No. You're not supposed to plug UPS's into surge strips or vise versa because the one can trip the other.

Unless you have a surge strip that doesn't have a breaker. Opti-UPS's actually come with a three outlet strip you can use. Basically nothing more than an AC input going through a varisotr and then split up into three outlets.
 
The joule rating on a UPS or surge strip is usually just the combined joule rating of the MOV devices contained inside.

And you can plug surge protectors into UPSes and vice versa, chain together surge protectors, hell you can even run UPSes off UPSes... and they shouldn't trip. The joule ratings will add.
 
gee said:
And you can plug surge protectors into UPSes and vice versa, chain together surge protectors, hell you can even run UPSes off UPSes... and they shouldn't trip. The joule ratings will add.
Click to expand...

They do trip.

I had a huge problem with this as a PBX installer. Power would go out and then the strip the customer plugged into the UPS would see the switch over to battery power as something that should warrant circuit protection. Whole phone system would go down.

This happened with a number of different brand UPS's: Cyber, APC, Opti, etc. The only time it didn't happen is if the UPS was an online UPS or the surge strip had no breaker on it.
 
What is an online UPS? Is that one that doesnt use the battery until the power accually goes out?

So I should probably plug the UPS into the wall, and then use the 4 battery backup plug-ins on the UPS, and then plug my surge strip into a different outlet and plug the rest of my stuff into that, instead of the UPS toget better protection?
 
jonnyGURU said:
They do trip.

I had a huge problem with this as a PBX installer. Power would go out and then the strip the customer plugged into the UPS would see the switch over to battery power as something that should warrant circuit protection. Whole phone system would go down.

This happened with a number of different brand UPS's: Cyber, APC, Opti, etc. The only time it didn't happen is if the UPS was an online UPS or the surge strip had no breaker on it.
Click to expand...
My desk at work has a BackUPS 600 feeding a power bar with another power bar plugged into the first. Works fine, even through outages.

Almost every SMPS out there - those in computers, VCRs, etc... all have MOV's connected across the AC line after their fuses to protect from overvoltage. I can't see why a UPS would see a different load.
 
It's not the MOV. And I didn't mean to say it's the UPS that trips or that the UPS "sees" a different load. It's the circuit breaker built into some of the nicer model power strips that trips.

For whatever reason, it sees the switch from mains to battery as a "surge" or something and it trips the breaker. I don't know why. But even once the UPS is in battery mode, if I hit the "reset" button on the strip, all is good again. But next time there's a brown out, "Pop!"

Strips like the cheap little Belkins don't do it. But the better ones like the APC's and ITW's will do it almost everytime there's a power outage.

That's probably why APC says not to hook a strip up to a UPS. Not that it happens to all strips, but better safe then sorry. Sort of like telling people they need a 600W power supply to do SLI. ;-)
 
metallicafan said:
Spectre - I read skimmed your FAQ, but didnt see anything on this subject. If the number of joules a surge unit is rated for is at all important many you could put some information on this in your FAQ.
Click to expand...

I missed this originally. I will work on an addition about the subject this week/weekend.
 
gee said:
My desk at work has a BackUPS 600 feeding a power bar with another power bar plugged into the first. Works fine, even through outages.

Almost every SMPS out there - those in computers, VCRs, etc... all have MOV's connected across the AC line after their fuses to protect from overvoltage. I can't see why a UPS would see a different load.
Click to expand...
I heard that when RMA-ing an APC UPS, they will ask whether it was plugged into a surge-protector. If yes, they supposedly refuse to honor the warranty.
 
drizzt81 said:
I heard that when RMA-ing an APC UPS, they will ask whether it was plugged into a surge-protector. If yes, they supposedly refuse to honor the warranty.
Click to expand...
True, at least the first part. I had to try to claim the warranty on an APC unit when it took down 4 machines that were plugged into it, and that question was the first thing they asked me. I don't know if they'll actually not honor the warranty over that, but it seems likely.

 
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