What size/capacity for UPS? (Calling all engineerds...)

[Sparky2]

There are so many choices of UPS (Uninterruptable Power Supplies) available these days. Hows does one calculate the size/cxpapacity needed to run their keyboard/guitar rig? Do they "play well" with voltage regulator/surge protector/power strips?

 

My ultimate solution is a single rack space unit with 4 battery back-up outlets to handle 4 keyboards, a PC, a rack with about 6 modules or effects units, some pedals, a QSC HPR122i 12" powered speaker, and a 60W guitar amp with a couple of tubes in it. Of course, the amps/speakers don't "need" battery back-up but since I'd like to keep everything plugged into the rack power strips it would be helpful.

 

I couldn't find a detailed discussion of this on the forum and I knew a few of you are EE's too. Any practical advice on this or am I over-thinking the issue? Thanks for the input.

 

Mark

[ITGITC]

 

 

Monty, I'll take whatever's behind door number one.

 

Sparky - you've got to add the current draw from each device before you can determine the size of the UPS you need.

 

Don't plug the QSC or the 60W guitar amp; they're going to draw too much current and they don't need the benefits of UPS.

 

Add the current draw from the PC, the 4 keyboards, and the ~6 modules to see what's needed. The PC will probably draw the most.

 

On the UPS I use with my computer, I've got an application that monitors the current draw. If you could borrow a setup like this, it would make it simple to determine the total current of whatever is plugged in.

 

Err... just which models are you considering?

 

Tom

 

[J. Dan]

The powered speaker and guitar amp would end up significantly increasing the size of he UPS needed - I'd seriously consider ditching them. Look at the specs or whatever is shown on each piece of gear in terms of Amps or Milliamps (1000 mA = 1A). Add them all up for your max total current draw. With a UPS, it's time vs current. The battery will have an amp-hour (AH) rating. One Amp-Hour means it can supply 1 Amp or 1 Hour. Theoretically, that would be 2A for 30 min, 0.5A for 2 Hr, etc. But in reality, check the specs on the UPS, because there will be a max current rating and the relationship of current to time won't be totally linear. If you see Watts, divide by 120 and that's Amps. ....oh, except if it's after a wall wart or something dropping the voltage, then divide by whatever the voltage is.

[RABid]

Adding to what was already said:

 

Most UPS units will have both battery and bypass plugs. The bypass plugs offer surge protection but not battery backup. These are good for printers and speakers. Also remember that these are rechargeable batteries. They will lose maximum charge over time. Figure out what you need, then increase it by a third. Plan on replacing the batteries after 2 or 3 years.

[Sparky2]

Thanks, guys. That will get me off to a good start. I should look at power requirements in watts and current requirements in Amps... So, a desktop PC (if I am at home) with a 200w power supply will likely draw the most (200W)? The PC3x requires 25W at turn-on, and 0.50A maximum to keep on. So am I correct in thinking that I would need anything more than 225W for these two pieces alone provided the current requirements are met or exceeded? It's nice to have the strat-up power requirements for a piece, but if it is not provided, is there a factor of safety I should apply?

 

ITGITC, I am looking at long list of readily available APC units, some of which claim to be rack-mountable. Thanks again. I'll make a list of requirements over the weekend.

 

Mark

 

I'l have to wait until I get home to add everything up.

[Tonysounds]

Keep in mind that these UPS units weigh anywhere from 15-40 lbs (my Tripplites weigh a solid 24 lbs.) and you may NOT want that in your rack.

[Sparky2]

Keep in mind that these UPS units weigh anywhere from 15-40 lbs (my Tripplites weigh a solid 24 lbs.) and you may NOT want that in your rack.

 

Ouch! I didn't get that far into the specs, yet. Come to think of it, my Tripplite 3-space voltage regulator/line conditioner is 27 pounds before the Road Ready Case... Maybe I'll rethink this and get a small one just to cover the laptop + PC3x + V-Synth XT and call it a day. The way bookings have dropped off.....

 

Mark

[ITGITC]

 

With a UPS, it's time vs current.

 

And often, there's not much time involved at all. The power could go off... and come back on within a few seconds. Even a UPS with a small battery could work for you in that scenario.

 

Sparky, I asked about which models you were considering because with that information, we can more easily narrow down a unit that might work for you.

 

Tom

 

[RABid]

Keep in mind that these UPS units weigh anywhere from 15-40 lbs (my Tripplites weigh a solid 24 lbs.) and you may NOT want that in your rack.

 

I almost bought an APC 1500 rack mount UPS to go with my rack mountable DAW until I saw that it weighed in at 53 pounds. I'm not sure studio racks are designed to hold that much weight by the ears.

[RABid]

I'll also say be really careful when looking at specs even within the same brand. Example:

 

APC Back-UPS Pro 1500 - UPS - AC 120 V - 865 Watt

 

APC Smart-UPS 1500 LCD - UPS - AC 120 V - 980 Watt

 

At first theire does not seem to be a lot of difference in these two units when you look at watts and VA. Not enough for the price difference. But when you look closely you see things like 3 minutes up time vs. 7 minutes up time. 8 hour charge vs. 3 hour charge. And maybe most important on output waveform, "Stepped approximation to a sinewave" vs. "Sinewave".

 

I went with the second for my new DAW. It may be overkill but it is an 8 core overclocked system with 8 HD's. The new computer overloaded what I was using before. At work we have several people using the APC Back-UPS ES series with no problem. They prevent troubles from power blinking and allow enough time to shut down if the power goes out. These come in at under $100 and are better than not using anything.

[Sparky2]

With a UPS, it's time vs current.

 

And often, there's not much time involved at all. The power could go off... and come back on within a few seconds. Even a UPS with a small battery could work for you in that scenario.

 

Sparky, I asked about which models you were considering because with that information, we can more easily narrow down a unit that might work for you.

 

Tom

 

Got it, Tom. I will go to the studio this weekend and play with a few load scenarios to define requirements. When I get this done I'll pose a few solutions here and see what y'all think I might be missing. Thanks again.

Mark

[Sparky2]

I'll also say be really careful when looking at specs even within the same brand. Example:

 

APC Back-UPS Pro 1500 - UPS - AC 120 V - 865 Watt

 

APC Smart-UPS 1500 LCD - UPS - AC 120 V - 980 Watt

 

At first theire does not seem to be a lot of difference in these two units when you look at watts and VA. Not enough for the price difference. But when you look closely you see things like 3 minutes up time vs. 7 minutes up time. 8 hour charge vs. 3 hour charge. And maybe most important on output waveform, "Stepped approximation to a sinewave" vs. "Sinewave".

 

I went with the second for my new DAW. It may be overkill but it is an 8 core overclocked system with 8 HD's. The new computer overloaded what I was using before. At work we have several people using the APC Back-UPS ES series with no problem. They prevent troubles from power blinking and allow enough time to shut down if the power goes out. These come in at under $100 and are better than not using anything.

 

Thanks! Good tips. I've got a bit of homework ahead of me before I can propose anything.

Mark

[MoodyBluesKeys]

APC are good units - I use a lot of them in my business.

 

Note that most UPS do not show output WATTAGE in their specs, but show output Volt-Amps. The two are not the same value due to something called Power Factor (a full explanation would be way deeper than you probably want). Assuming a usual powerfactor for loads like notebook computers and keyboards, if the specs are in VA instead of watts, use a factor of about 3/4 - meaning that 100 VA would only be about 75 watts.