Looking for a uninterruptible power supply

[Keened]

In a modern setup, the most expensive part of a UPS is the battery. If you like DIY I'd say look at some of Cutting Edge Power's concepts, a sinewave (modified or pure) inverter/charger and a bunch of batteries is pretty much all you need.

There are also a bunch of sealed box solutions (Blue Yetti, that lion mascot one, etc) who I can't personally vouch for but other people seem to be reasonably happy with them.

 

[Speedskater]

a UPS's power rating is for resistive loads.
a power amp with a linear power supply, will draw current pulses much higher the an equivalent resistive load.

 

[Doodski]

a UPS's power rating is for resistive loads.
a power amp with a linear power supply, will draw current pulses much higher the an equivalent resistive load.

How about a desktop PC power supply?

 

[dlaloum]

I have a Cyberpower UPS that I use for my home NAS/Server....

Any audio gear that has switched power supply will be perfectly happy with any sort of UPS - but if you have gear with traditional linear power supplies - then you are far better off with a proper sine wave power feed.

The ones without proper sine wave will have lots of hash and noise on the power line, some of this is likely to make its way through audibly on Linear PSU's (unless their filtration is exceptionally good...) - yes your mileage may vary, still I would not feed my audio gear anything less than sine power.

 

[sergeauckland]

I have a Cyberpower UPS that I use for my home NAS/Server....

Any audio gear that has switched power supply will be perfectly happy with any sort of UPS - but if you have gear with traditional linear power supplies - then you are far better off with a proper sine wave power feed.

The ones without proper sine wave will have lots of hash and noise on the power line, some of this is likely to make its way through audibly on Linear PSU's (unless their filtration is exceptionally good...) - yes your mileage may vary, still I would not feed my audio gear anything less than sine power.

You don't feed anything with sine power as the mains has some 3% harmonic distortion which on a 'scope won't look sinusoidal, yet the audio equipment works fine. I run a whole radio station off APC UPSs which work just fine, no hash or noise getting through normal commercial equipment power supplies.
Yes, UPS ratings are for resistive loads, so some derating is required for linear power supplies, but typically 20-25% seems adequate.
I think far too much is made of audio equipment being somehow more fussy of mains than other stuff. It very rarely is, and if it is, then it's a poor design.

S

 

[DonR]

How about a desktop PC power supply?

PC PSU has power factor correction so looks like a resistive load to the UPS.

 

[dlaloum]

You don't feed anything with sine power as the mains has some 3% harmonic distortion which on a 'scope won't look sinusoidal, yet the audio equipment works fine. I run a whole radio station off APC UPSs which work just fine, no hash or noise getting through normal commercial equipment power supplies.
Yes, UPS ratings are for resistive loads, so some derating is required for linear power supplies, but typically 20-25% seems adequate.
I think far too much is made of audio equipment being somehow more fussy of mains than other stuff. It very rarely is, and if it is, then it's a poor design.

S

Most APC UPS's are sine wave.... the cheaper ones don't do double conversion...

From their very bottom of the line models, the Easy UPS are sine, the Back-UPS (glorified power boards) - use a "stepped wave form" (ie: square wave or multi-square wave) - needless to say a Square wave being measured as Sine + THD is going to score massively high on THD!!

Difference Between Square & Pure Sine Wave Inverters | PSS

Do you want to get a Sine Wave Inverter or Square Wave Inverter? Check our blog & read the difference between the Square & Pure Sine Wave Inverters. Read it!

pssdistributors.com.au

I don't believe anyone uses stepped waveform UPS's for data centers, computer rooms, medical systems, etc... pretty much anything of import - their only benefit seems to be cheapness.

 

[dlaloum]

Took me a little longer to find the calculations around Sine wave vs Square wave with the difference as THD...

Understanding, Calculating, and Measuring Total Harmonic Distortion (THD) - Technical Articles

Total harmonic distortion (THD) is a measurement that tells you how much of the distortion of a voltage or current is due to harmonics in the signal.

www.allaboutcircuits.com

To quote the key line:
A square wave actually has about 48.3% total harmonic distortion meaning that the RMS of the harmonics is about 48.3% of the RMS of the fundamental frequency.

 

[sergeauckland]

Most APC UPS's are sine wave.... the cheaper ones don't do double conversion...

From their very bottom of the line models, the Easy UPS are sine, the Back-UPS (glorified power boards) - use a "stepped wave form" (ie: square wave or multi-square wave) - needless to say a Square wave being measured as Sine + THD is going to score massively high on THD!!

Difference Between Square & Pure Sine Wave Inverters | PSS

Do you want to get a Sine Wave Inverter or Square Wave Inverter? Check our blog & read the difference between the Square & Pure Sine Wave Inverters. Read it!

pssdistributors.com.au

I don't believe anyone uses stepped waveform UPS's for data centers, computer rooms, medical systems, etc... pretty much anything of import - their only benefit seems to be cheapness.

Rather depends on what you mean by 'sine wave'. A sine wave with 3% harmonic distortion, as decent UPSs put out, isn't in my view a sine wave any longer. It doesn't look like a sine wave on a 'scope. Sure, it's not a square wave, nor a stepped wave, but a sine wave it ain't!

Ditto normal mains, which typically has around 3% THD. Sine-like perhaps.
S.

 

[dlaloum]

Rather depends on what you mean by 'sine wave'. A sine wave with 3% harmonic distortion, as decent UPSs put out, isn't in my view a sine wave any longer. It doesn't look like a sine wave on a 'scope. Sure, it's not a square wave, nor a stepped wave, but a sine wave it ain't!

Ditto normal mains, which typically has around 3% THD. Sine-like perhaps.
S.

Ahh I see what you are saying - yes our mains have been imperfect since the day they were invented - but far better than the alternatives!

With the move to renewable energies, and inverter based power generated from various forms of storage - we are starting to move into the era of solid state inverter based power rather than rotating iron and coils.... I guess we can look forward to our mains power being far better approximations of sine waves.... and the better the approximation, the less noise there will be for our audio gear to filter out.

 

[DonR]

Well there you go... speak of the devil and receive a 5-hour power outage. I was on the cusp of firing up my gas-powered square wave generator when the power came back on a few minutes ago. UPSs lasted up to 2 hours until they died.

 

[ShiZo]

cyberpower cp1500pfclcd, without a doubt

 

[pma]

Standard UPSs don't output pure sine waves,

That's correct. In a "normal" mode (mains run, battery not activated) the output shape is quite same like the mains outlet voltage. In a battery back-up mode, the ouput shape is a step-like wave. See below the output of APC 650VA UPS.

"normal" run

battery run

 

[dlaloum]

That's correct. In a "normal" mode (mains run, battery not activated) the output shape is quite same like the mains outlet voltage. In a battery back-up mode, the ouput shape is a step-like wave. See below the output of APC 650VA UPS.

View attachment 227360
"normal" run


View attachment 227361
battery run

APC also have double conversion UPS' mostly in their business range, not the cheaper consumer models.

Those have the output power ALWAYS going through a synthetic sine wave generator - hence double conversion - the input power is always converted to DC, and used to charge the batteries and power the output inverter....

The output inverter runs off input DC power when available, or battery DC power when running as UPS.

Either way - the output power is always fully filtered, as it is fully "regenerated" to eliminate any noise (other than noise generated within the inverter itself).

The problem is, most of those UPS units have loud fans - and are designed for data centres and comms rooms.... you would not want one in your lounge room!!

 

[Webninja]

Had Cyberpower for years, but had some fail recently. High whine and one would shut off randomly.

Switched to APC, been about 6 months, quiet and made it through a few short outages.

I have bought batteries for older units, but they are almost the same price as a new unit

 

[FrankieC]

APC also have double conversion UPS' mostly in their business range, not the cheaper consumer models.

Those have the output power ALWAYS going through a synthetic sine wave generator - hence double conversion - the input power is always converted to DC, and used to charge the batteries and power the output inverter....

The output inverter runs off input DC power when available, or battery DC power when running as UPS.

Either way - the output power is always fully filtered, as it is fully "regenerated" to eliminate any noise (other than noise generated within the inverter itself).

The problem is, most of those UPS units have loud fans - and are designed for data centres and comms rooms.... you would not want one in your lounge room!!

Very true, and I am starting to do a bit research, and seeing people replacing the stock fan with quieter one on double conversion UPS like Eaton, which looks like an interesting workaround

 

[Cars-N-Cans]

Thanks, 'simulated sinewave' had a slight whiff of 'UPS snakeoil', at least in a domestic setting (I populate data centres with compute and storage in my day job, so I have some familiarity with commercial units as a business consumer). I'd originally purchased the VP1600 which is cheaper and has simulated sinewave output, but it had a fault and I could not find a replacement at a reasonable cost (hence the 'upgrade' to the more expensive unit).

Most equipment with SMPS' will be absolutely fine with the modified sine (edit: or "simulated sine"), but I would use care with linear amplifiers. The RMS current and harmonics can get a bit out of control, and possibly blow rectifiers or capacitors. Basically they are being fed a square wave with some deadtime at the zero crossings and the sharp transients can really tax conventional mains transformers since they are not made to run at anything more than 50/60 Hz. Personally I keep my audio equipment OFF of my UPS and just have the PC (and possibly laptop) on there. They don't offer that much runtime with lead acid batteries. Better bet is a pure sine inverter with Lithium Iron Phosphate batteries. That will power most of what you want to keep you busy in the dark without damaging any of your gear. For reference here are the various waveforms. Anything other than pure sine should only be used with SMPS' since they are usually designed with that eventuality in mind.

 

[Cars-N-Cans]

Just had multiple power outages in a single day. I've been wanting to get a UPS for a long time now. I think I will finally commit to this.

The thing is. I will be in the same room with the UPS, so I'm looking for a device that is:

- Quiet
- Can handle high room temperatures (in summer - 35°C/95°F)
- Online UPS (Voltage/Frequency independent)

I am looking to run my NAS that contains all the music, my workstation plus the amps off of it. I think, worst case if power goes while I'm gaming, I might be pulling 500W. For sure less than 1000W.

What type of amps do you have? Anything powered by something other than an offline power supply/SMPS should be kept off of them if its a conventional type with a simple scheme for generating the AC. Really you only want things on there that will be damaged by outages, like PCs and music servers. Keeping everything else off it gives you more time to shut down and broadens your options. I personally use a 15+ year old APC XS 1300 that I scrounged from an office. Slap some new batteries from the hardware store in it and it was good to go. For the rest of the equipment, just make sure it has a good surge protector to save it from any transients during brown-outs.

 

[Berwhale]

What type of amps do you have? Anything powered by something other than an offline power supply/SMPS should be kept off of them if its a conventional type with a simple scheme for generating the AC. Really you only want things on there that will be damaged by outages, like PCs and music servers. Keeping everything else off it gives you more time to shut down and broadens your options. I personally use a 15+ year old APC XS 1300 that I scrounged from an office. Slap some new batteries from the hardware store in it and it was good to go. For the rest of the equipment, just make sure it has a good surge protector to save it from any transients during brown-outs.

For the UPS in my study; only the amps in my iLoud MTMs, but you're right, I should probably move them off the UPS. The other two UPS have Synology NASes, a micro ESXi host and bits of networking equipment hanging off them.

 

[Speedskater]

While very few of us have a current probe (they are rather expensive! The real test is to examine the current waveform to the AC input of a big amplifier playing at high power. Is the waveform the same when using the AC line and the UPS?