What UPS for 1900 Watts?

First I’d say you can start by adding up the wattage of all the devices you plan to plug into the UPS. Then multiply the result by 1.66 to obtain the minimum necessary UPS capacity in VA. I think 600 VA for all your devices is immediately too low. A projector likely consumes a lot (because of the lamp) and I’ve read that it’s really not good for its lifespan to be switched off abruptly too often (without the cooling process having occurred).

But I think there are other factors to consider in your purchase and that you’re forgetting:
my research on the subject may partly answer your questions or raise others worth asking when buying a UPS; this is a message I wrote following a thread at https://forum.macbidouille.com/index.php?showtopic=257793.

after learning a lot about UPSs thanks to forums (thanks to you) and thanks to various information or sales sites, I now share my state of knowledge and my buyer’s experience of the Liebert Emerson PSI 1440VA model (purchased for around 400 euros including tax from www.onduleurs.fr this February 2009 - special offer on this brand).

Description of my working environment:

I am a music composer and own a small professional studio for creating/producing music.

I use:

- 1 Mac Pro Xeon 8-core 2.8 GHz currently equipped with 2 internal hard drives (probably soon 3), standard graphics card supplied with the computer
and connected to this computer (directly or via the audio interface mentioned in this list) the following peripherals:

- several external hard drives, but I would say at most 3 are used simultaneously (in addition to my internal hard drives).
- 1 RME Fireface 800 audio interface
- 1 Mindprint 2-channel preamp
- 1 home CD player
- 2 powered studio monitor speakers (each speaker 80 W)
- several electrostatic microphones (very sensitive studio mics)
- 1 Freebox modem
- 1 MIDI keyboard (digital piano)
- 1 19-inch monitor (likely soon a 2nd monitor)
- 1 inkjet printer

What I expect from my UPS:

A] protection of my equipment against micro-outages, surges or voltage drops, notably through continuous regulation of the voltage sent to my machines
B] without sacrificing the quality of the reconditioned electrical signal because I use audio equipment for recording (audio waves)
C] without sacrificing the silence of my environment because when I’m recording sound it’s necessary that the capture is not “polluted” by unwanted noise
D] ...for an affordable price?

Notes:

- I previously had a Furman power conditioner, a well-known brand in recording studios. It failed after only 2 years after showing voltage variations that surprised me (I learned since that you should not expect the EDF network to provide ultra-stable power and that this situation will not improve...). This device was only a surge suppressor that mainly cleaned the current frequency (regenerated a perfect 50 Hz) and tripped on under- or over-voltage.
- before installing my current UPS, I noticed computer crashes at the exact moment I heard a small crack from my oil bath heater (my workflow equipment and this heater were on completely independent electrical lines)
- before installing my equipment, I had the electrical box of my studio redone and created 4 new dedicated electrical lines for my sensitive equipment (computing and music). Good grounding quality was verified.

Here are my answers to the question “which type of UPS fits my equipment and my objectives?” I will address, last, the question of the UPS power (in Volt Amps) since it ultimately depends on the machines to protect.

Consider each objective A/B/C/D in turn:

A] protection
1) Know that when a device connected to the computer (directly or via another peripheral) is not plugged into the UPS but directly to the mains, there is a risk of compromising protection for the whole chain. So my first choice was to consider wiring all the devices cited above into the UPS so the entire chain remains in a “closed circuit” from the UPS.
2) Also know that off-line UPS technologies do not provide continuous regulation of voltage drops or surges, but only a battery relay in case of power outage. As long as there is no power outage, the UPS delivers the voltage as provided by the grid without touching it. So I decided to move toward the higher “Line-interactive” technology, which continuously interfaces between your equipment and the grid to regulate the voltage (positive or negative) as needed. However, this technology, unlike the “On-line” range (the most complete and also most expensive), does not regenerate the frequency of the current (50 Hz).

B] signal quality
Some UPS units deliver a square (binary) waveform, others a sinusoidal waveform. The former suit purely IT equipment (computer, hard drives) but are not recommended for other electrical equipment (such as audio equipment) for which a sinusoidal signal is preferred, though it is more expensive. So I chose, despite the higher price, a UPS that provides a sinusoidal signal.

C] noise
I’ve read very contradictory information about UPS noise, especially for MGE brands. The noise of a UPS mainly comes from its cooling. When it occurs, this noise is really bothering, even incompatible with my activity. But is it permanent?
Speaking with the advisors on www.onduleurs.fr (a retailer that sells 4 major UPS brands), one told me that in the Line-Interactive technology the cooling noise only triggers when the battery needs recharging, which happens only during a power outage (even micro-outages). So it’s not all the time.
That said, choosing a Liebert Emerson model, another advisor told me “those are completely silent, unlike MGE.” I understood that MGE ventilation is regularly used; is that only the case on models above 1000 VA as I had read?
In any case, my UPS (Liebert Emerson PSI 1440VA) is perfectly silent (except during startup when the battery took several hours to charge, causing the ventilation to run at a high decibel level, like three times the decibels of the PC I had in 1995 to give you an idea...). Another thing is certain: On-line technology UPS units (which are of little interest to individuals due to their price) are loud continuously because the battery constantly generates the current distributed to the machines. This category should be avoided if you want a silent UPS, or else you should place the UPS in another room from where you work (many studios have a room called “nodal” where the noise-producing machines are placed, not mine).

D] price
At the start of my search, I hoped a device under 100 euros could meet my needs... That’s not the case, but the price of all my equipment and the importance of avoiding data corruption in my activity seemed to justify spending 400 euros to guarantee protection. I excluded the “on-line” technology because of its price, and also because of its noise.
Fortunately, in February 2009, the site www.onduleurs.fr offered a promotional price on the Liebert Emerson PSI 1440VA UPS (400 euros while it is sold at 600 by some retailers). This UPS matched my expectations (search PSI 1440 on the site).

Finally, regarding power (in VA): based on my information gathering, it seemed preferable and comfortable given all the equipment I had to plug into the UPS (cf. paragraph A) to opt for a model around 1500 VA. In case of overloading (too many devices connected simultaneously), the UPS signals this with a warning light.

CONCLUSION:

The UPS I bought, a Liebert Emerson PSI 1440 VA seems to meet the objectives I set. Its price is high in absolute terms (I bought it for 400 euros including tax), but relative to market prices and its usual price, I think I made a very good purchase. As of the time I’m writing this post, I installed the UPS last night, so I don’t yet have enough hindsight to say it fully meets its commitments, but I already appreciate its silent operation (and that is a strong requirement for me). Additionally, it offers 8 outlets, which is a lot. However, since these outlets are IEC format, I also bought (20 euros each including tax) multipliers 1 IEC male to 3 French female sockets for connecting some of my machines (notably my external hard drives).

For those with goals similar to mine, I therefore recommend this UPS.

I also note the very good availability and pedagogy of the technicians-sellers at www.onduleurs.fr. I’ve cited this site many times, but you should know I have no privileged link with this shop; I’m simply very satisfied with their quality of service.

There you go, I’ve spent a lot of time

For a load of 1900W, a 3kVA UPS remains adequate; it will then be loaded at 90% (in general a 3kVA UPS can provide 2.1kW), but given your budget you won't go far.