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Author Topic: rackmount UPS  (Read 3125 times)

Weogo Reed

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Re: rackmount UPS
« Reply #30 on: April 13, 2018, 12:26:42 pm »

Hi Debbie,

Good question about modified vs 'pure' sine wave.
My understanding is there are modified sine wave variations that have very coarse steps, and
others that are closer to actual sine.
I believe an O-scope will show the wave form.
In my experience, the decent quality, modified sine wave units have (mostly)worked fine, though
you may hear some transformer buzzing when on battery.

Again, just my experience, but the bigger difference is whether you go double-conversion.
Particularly when running on a genny, this will separate the women from the girls.

I did a weekend lecture series at a camp on a big genny.  Every time the big freezer kicked in, the
old genny would groan, the little line-interactive UPS would go to battery, the
01V96 mixer transformer would buzz, and then a couple seconds later everything was fine.
The mixer had to sit near the presenters who heard the buzzing tranny.
I removed the UPS and the 01V96 capacitors carried the mixer through the genny ups and downs.
In this situation, a double-conversion UPS would have worked pretty quietly(except for the ones with noisy fans).

Remember, many of these UPS units are built for server-room type applications, and noisy fans aren't a big deal there.
And the fans probably aren't an issue for RnR shows either.

Thanks and good health,  Weogo


So how important is pure sine wave? I see this product doesn't have it. The one I am using right now does.....I like the lithium ion battery idea.
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Debbie Dunkley

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Re: rackmount UPS
« Reply #31 on: April 13, 2018, 01:21:48 pm »

Hi Debbie,

Good question about modified vs 'pure' sine wave.
My understanding is there are modified sine wave variations that have very coarse steps, and
others that are closer to actual sine.
I believe an O-scope will show the wave form.
In my experience, the decent quality, modified sine wave units have (mostly)worked fine, though
you may hear some transformer buzzing when on battery.

Again, just my experience, but the bigger difference is whether you go double-conversion.
Particularly when running on a genny, this will separate the women from the girls.

I did a weekend lecture series at a camp on a big genny.  Every time the big freezer kicked in, the
old genny would groan, the little line-interactive UPS would go to battery, the
01V96 mixer transformer would buzz, and then a couple seconds later everything was fine.
The mixer had to sit near the presenters who heard the buzzing tranny.
I removed the UPS and the 01V96 capacitors carried the mixer through the genny ups and downs.
In this situation, a double-conversion UPS would have worked pretty quietly(except for the ones with noisy fans).

Remember, many of these UPS units are built for server-room type applications, and noisy fans aren't a big deal there.
And the fans probably aren't an issue for RnR shows either.

Thanks and good health,  Weogo

I have had a couple of occasions using very good quality diesel generators for shows but my UPS has not liked them at at all.  It will get completely confused and flash from 120v to battery and I have had to remove the UPS completely. However, when I use something like the Honda EU3000, Yamaha EF3000 etc, I get no problems with my UPS - it acts just like it does on power mains.

So.....you are saying that pure sine wave is not as important as double-conversion when it comes to UPS?
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Tim McCulloch

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Re: rackmount UPS
« Reply #32 on: April 13, 2018, 02:28:28 pm »

I have had a couple of occasions using very good quality diesel generators for shows but my UPS has not liked them at at all.  It will get completely confused and flash from 120v to battery and I have had to remove the UPS completely. However, when I use something like the Honda EU3000, Yamaha EF3000 etc, I get no problems with my UPS - it acts just like it does on power mains.

So.....you are saying that pure sine wave is not as important as double-conversion when it comes to UPS?

Get a CHEAP inverter that plugs into your car's accessory power port (cigarette lighter) and try to power up the parts of your kit that will be on the UPS.  You'll find some things don't care much about the wave form and maybe other things won't work well or at all.  Which ones?  Hard to say.  I think 1 of our UPSs is modified sine wave and I don't recall any problems with the connected loads.

I suspect the bigger gensets you've been connected to have experienced frequency changes as the engine responds to changing load conditions.  Some UPS have more tolerance for input frequency, others are tighter.

Weogo's point is exactly why sometimes a generator needs a load bank to keep the genset running at a higher output (less revving up/down) when connected loading is low.
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Bob Leonard

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Re: rackmount UPS
« Reply #33 on: April 13, 2018, 06:00:05 pm »

Pretty good points from you and Weogo Tim. Fact is that a UPS is not designed to hold up the hardware for any time more than it needs to gracefully shut the equipment down in the case of a power loss. Most hardware in my day world is either cabled to the UPS, or networked to the house backup system. Software is then applied to the OS and the grace period for shutdown is never much more than 10 minutes or less. In the case where the systems are located in a data center that would cover any period of time where the building generators fail to kick in. Any time a building generator(s) fail to kick in before 10 minutes are up makes for a very sad day for the people who own the building.

So the in rack UPS is actually a third failure point. The building generators, the battery banks, then your own UPS(S). After that it's call Mom and tell her you won't be home for dinner, breakfast, or even the next nights dinner.

In this world though the rack mounted UPS is a device allowing you to, as said previously, properly shut down the critical hardware in order to prevent OS corruption or component failure when the power surges back on. A decent UPS only needs to provide good clean power and 5-10 minutes of up time. and someone at the helm who is smart enough to shut down the console DSP, etc.. What does it matter if the powers gone? The show stops until it comes back anyway, and once back up you can bring the boards, etc. back up clean and on with the show. And again, buy good quality brand name hardware for the purpose. That means hardware that can be fixed in the USA, hardware that has batteries you can buy anywhere, and hardware that has phone support behind it.
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