How many VA/Watts UPS for outboard gear? Do you really need Pure Sine Wave?

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canidoit

Well-known member
Joined
Apr 6, 2009
Messages
1,174
Location
Australia
I have this 1500VA/900W UPS that produces ON BATTERY Pure Sine Wave at 900W.
https://www.cyberpowersystems.com/product/ups/pfc-sinewave/cp1500pfclcd/
I am considering sharing this UPS for my computer with my outboard gear but unsure whether it can handle it, if not, I might just buy another one.

How many outboard gear could this safely use - interfaces, compressors, eqs, 500 series racks, etc.

Is there like a simple estimate like, 500 watts is about 4 pieces of tube outboard gear?

Are these UPS better than the Furman power conditioners? Which of these two would prevent/minimise ground loops, hums, noise, etc.

Are Pure Sine Wave UPS necessary if it only uses the Pure Sine Wave when the UPS is running on battery. I mean the purpose of UPS at home is just to have enough time to save your work and shut down, so simulated sine wave or non sine wave should not be that bad on studio gear if its only for 5-10 minutes?
 
Most gear does not need a pure sine wave... unclear how pure mains power even is.

The blurb says PFC sinewave. Power Factor Correction spreads out current draw to reduce IR losses.

If you already have one it seems you could perform an experiment.

JR
 
Amir over at Audio Science Review has done tests on some company's "power regenerators" and how well they work (if they do what they claim at all) and if it's needed. He tests the unit itself, then he tests audio equipment when it's not plugged into it, and when it is, and there is no measurable difference on the output.

As he says in his accompanying videos, your gear doesn't care about the input since wave since every device already has a "regenerator" in it turning the AC into DC and filtering it. It's called a power supply.
 
JohnRoberts said:
Most gear does not need a pure sine wave... unclear how pure mains power even is.

The blurb says PFC sinewave. Power Factor Correction spreads out current draw to reduce IR losses.

If you already have one it seems you could perform an experiment.

JR
Click to expand...
Thanks John,

Oh I see, so I guess mostly measurement devices would benefit from pure sine wave?

I could do an experiment, but don't you need a safety margin with the UPS for when the audio gear powers up?

I do notice, once the fans on the computer and GPU starts, I noticed the load increase substantially in the UPS.

I might give it a try as I am still trying to troubleshoot some hum/noise I am getting from a rack which is just outboard gear. That is what I want to use the UPS with and hopefully fix that issue.
 
Products are designed to work properly with typical mains power... whatever that is.

JR

PS: FWIW last century when I was dealing with international markets OZ was notorious for pretty extreme hi line/low line mains voltages. Apparently for some very long mains spurs out in the boonies we could see unusual hi line voltage at the sending end of a long spur, and unusual low voltage at the far end.
 
Yes, Australia has some very creative power distribution systems. SWER (single wire earth return) is commonly used at the edges of the grid and is exactly what it sounds like. You get a single wire with some volts on it and you plug the other end into the soil. What voltage and waveform you get depends what the neighbours are up to.
 
This is a rule of thumb that I've used for years to estimate power consumption of studio gear.

I examine each piece of gear, locate the AC mains fuse location and write down the fuse value noted next to the fuse holder of each item. This also serves as a method to create a list for making an inventory of a stock of replacements to have on hand (be sure to note things like fuse size and slow/fast blow for the inventory).

Add up all of the AC mains fuse current ratings for each device. That should provide a total amperage for everything with a bit of "headroom".

Bri
 
Brian Roth said:
This is a rule of thumb that I've used for years to estimate power consumption of studio gear.

I examine each piece of gear, locate the AC mains fuse location and write down the fuse value noted next to the fuse holder of each item. This also serves as a method to create a list for making an inventory of a stock of replacements to have on hand (be sure to note things like fuse size and slow/fast blow for the inventory).

Add up all of the AC mains fuse current ratings for each device. That should provide a total amperage for everything with a bit of "headroom".

Bri
Click to expand...
Hi Bri,

So lets say the Distressor uses a 0.3amp X 250 volts fuse. This would mean 75 watts.

So for a 750watt UPS, I could run 10 distressors?

Looking at some outboard specs, they fall in the areas of 0.5amps X 250v fuses. So I guess 900watts UPS would give me about 7 units. But that would only be if there was a power out and the UPS has to run on batteries? Is that correct?

If the UPS is running on batteries due to a power out and there were more than 900watts plugged in, what usually happens? Does some of the units turn off, or the whole UPS stops working?

Thank you.
 
Fuses are sized to handle worst case turn-on current surges, so using that to predict average current consumption is likely to overstate it.

Some countries require VA specs screened on the chassis.

JR
 
When I was a Gaffer for film/video, we were trained to add up the amps of the lamps that were going to be used, and add 50% safety margin.

I wasn't aware there was gear out there that didn't have it's amperage load printed on it somewhere. Everything I've ever owned has had - just lucky I guess.
 
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k brown said:
When I was a Gaffer for film/video, we were trained to add up the amps of the lamps that were going to be used, and add 50% safety margin.
Click to expand...

with incandescent lamps there can be a huge difference in current draw cold vs. hot.
k brown said:
I wasn't aware there was gear out there that didn't have it's amperage load printed on it somewhere.
Click to expand...
we are on a DIY forum...

JR
 
It's also worthwhile looking at the power coming into your facility. I live in a rural area of Colorado and with no compressors or other electrical noisemakers, my mains power has 10-12% THD. Measured in a non-industrial part of Denver it was about the same. I used a purpose built AC Power Analyzer (Xitron), for the measurements. Several companies make Power Regenerators that turn the mains power into DC and then back to AC with < 1% THD. Does this matter? The HiFi enthusiasts believe so and shell out several $K to companies like psaudio.com. Industrial companies like Behlman.com have less pricey and less elegant looking rackmount solutions. eBay is a good place to look. My initial conclusion is for vintage mics or anything with a traditional transformer and rectified & filtered DC, maybe yes, but if it has a switcher inside, probably not.

If your mains voltage hops around a lot, I'd recommend an overlooked and inexpensive device by APC (and others), that switches taps on an internal transformer to raise or lower the mains voltage using FETS-so fast switching. Voltage Regulators | APC USA. $70 for a 1200VA unit from APC.

Another approach is Solar with battery backup and an inverter and stay clear of mains power altogether.
 
canidoit said:
Hi Bri,

So lets say the Distressor uses a 0.3amp X 250 volts fuse. This would mean 75 watts.

So for a 750watt UPS, I could run 10 distressors?

Looking at some outboard specs, they fall in the areas of 0.5amps X 250v fuses. So I guess 900watts UPS would give me about 7 units. But that would only be if there was a power out and the UPS has to run on batteries? Is that correct?

If the UPS is running on batteries due to a power out and there were more than 900watts plugged in, what usually happens? Does some of the units turn off, or the whole UPS stops working?

Thank you.
Click to expand...
Your math makes sense to me for Oz (a 250 VAC country).

As John Roberts mentioned, adding up the fuse ratings will result in a total that is conservative vs the Real World. I referred to that as "headroom"...probably not the best word in this situation. What I mean that the total value calculated via adding up the individual fuse ratings would be a result that would be Plenty Safe with a Fudge Factor.

Years ago, I was designing and building pro digital video production facilities which had a zillion various rack mounted units. I had to "guesstimate" the required AC mains requirements in order to specify how many Mains branch circuits would be necessary without actually having the gear in hand during the design/specification phase.

My "add up the fuse ratings" method always gave me a comfortable margin in the finished system. I gave up trying to get actual values from the manufacturers who often didn't understand my request, or would reply with "somewhere between 200 and 800 VA"!

Want Real World values? Use an Amprobe (clamp-on AC ammeter) and take actual field measurements. Amprobes are used by electricians for this purpose, but are intended to measure current through a single conductor in the circuit....like a wire coming out of a single circuit breaker in the Mains panel.

To measure the current consumption of an individual unit with the typical Mains cord, I built a simple "jig". Male Edison connector to plug into the Mains source, insulated wire jumpers connecting to a female Edison (to power the device) that were long enough to allow the Amprobe to be clamped around one of the current carrying conductors.

As far as a UPS and what happens if the load is above the power rating? I think that would be a function of how the UPS was designed.

Bri
 
I can attest that an ups or a power conditioner should be as close to a pure sine wave output as you can get. A certain monster conditioner would output a square wave, in turn this killed smpsu’s
Discovered long ago when a certain model kept creeping up into racks at studios. When monster left I thought it wouldn’t be a problem again until one audio company put out a clone of that monster unit.
 
pucho812 said:
Yes. But output matters… as noted above be it a Ups or power conditioner
Click to expand...
Indeed!! In a perfect world, our Mains power (sine wave) would would measure at 0.0001% THD and IM! <GRIN>

I'm making a slight jump now. Readers here that are much younger than me will be asking "whaaa???"

The Bell System and all of the spinoffs maintained a huge network of pairs of wiring to houses and businesses for POTS (Plain Old Telephone Service). You know, that pink telephone hanging on the wall in Grandma's kitchen.

All those pairs ran back to a Central Office (CO). In that building was a literal "battery farm" along with diesel generators outside.

A Big Ass UPS system! <g>

Bri
 
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We used a pure (what ever that is) sine wave to calibrate current sensors like 4 to 20 ma and 0 to 5 volt for HVAC folks.

The voltage did not jump around which made trimming the calibration trim pot a lot easier.

The pure sine wave helped to us to be honest about how many rms amps equaled a 20 ma output on the closed loop sensor circuit.
 

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