Small UPS Recomendation

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Paul1977

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#287176 11-Jun-2021 14:13

I'm after a small UPS to put in my 9RU network cabinet which still has a bit of room left in the bottom. The idea being to keep providing power for Internet and security cameras for 20-30 min.

It would be to power:

ONT
Router
500W PoE switch (but unlikely to ever need to supply more than 100 watts to PoE devices)
TV multiplexer
Ring video door bell
TV multiplexer
Cabinet cooling fans

Most of the devices use DC adapters, but I'm a little confused when working out my power requirements (and the difference between watts and VA never made sense to me).

With the DC adapters the input wattage (V x A) always seems a lot higher than the output wattage. Which one do I use when working out how much power I need?

A UPS with network connectivity would be ideal, but not essential if it will add too much cost.

What brand would most people recommend (without breaking the bank).

Thanks

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#2725297 11-Jun-2021 14:27

the labels on a power brick will be the maximum it will draw, likely will draw less than that when the device is running.

add up all the maximums on the power bricks and see what you get

How much space is in the bottom? my APC 750VA ups is 160mm tall and about the same wide. its about 400mm deep with the cables in the back.
APC suggest with a 150w load it will last 30 mins

FWIW, Im currently using 170w, which is 202VA powering my desktop computer, 1x 34in screen (45w) and a couple of switches.

Paul1977

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#2725309 11-Jun-2021 14:54

Jase2985:

the labels on a power brick will be the maximum it will draw, likely will draw less than that when the device is running.

add up all the maximums on the power bricks and see what you get

How much space is in the bottom? my APC 750VA ups is 160mm tall and about the same wide. its about 400mm deep with the cables in the back.
APC suggest with a 150w load it will last 30 mins

FWIW, Im currently using 170w, which is 202VA powering my desktop computer, 1x 34in screen (45w) and a couple of switches.

Thanks, but is it the listed input or output power of the bricks I add up? I actually just remembered I have a power adapter that measures power draw somewhere. If I can find that it might be useful.

There's enough height, but cabinet may not be deep enough so may have to orientate the UPS along the width of the cabinet, but that's not a problem.

Rikkitic

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#2725362 11-Jun-2021 15:09

Maybe this will help:

In an AC circuit, power and VA mean the same thing only when there is no reactance . Reactance is introduced when a circuit contains an inductor or capacitor . Because most AC circuits contain reactance, the VA figure is greater than the actual dissipated or delivered power in watts. This can cause confusion in specifications for power supplies. For example, a supply might be rated at 600 VA. This does not mean it can deliver 600 watts, unless the equipment is reactance-free. In real life, the true wattage rating of a power supply is 1/2 to 2/3 of the VA rating.

When purchasing a power source such as an uninterruptible power supply ( UPS ) for use with electronic equipment (including computers, monitors, and other peripherals), be sure the VA specifications for the equipment are used when determining the minimum ratings for the power supply. The VA figure is nominally 1.67 times (167 percent of) the power consumption in watts. Alternatively, you can multiply the VA rating of the power supply by 0.6 (60 percent) to get a good idea of its power-delivering capability in watts.

Think of watts as DC power and VA as AC. For some things they will be essentially the same. With a wall wart or other adapter or power supply, VA refers to the power being drawn from the source, while watts refers to the power available to the device. Wherever you see VA mentioned, use that as your power figure. Otherwise use the watts one.

(If you are feeding any of your devices directly with DC from the UPS, the watt figure applies. If you are supplying mains voltage to anything, use the VA one.

(I have a Constant Vigil Sentry Lite that supplies DC to my router and ATA. You can order it with any voltages you need but it probably wouldn't have enough capacity for your requirements. It is a great little unit though and works well for me.)

Plesse igmore amd axxept applogies in adbance fir anu typos

littlehead

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#2725367 11-Jun-2021 15:16

We've used the Eaton 5E line a lot at work for small-ish loads and I use them personally at home as well. The 850VA/480W version is what I use. It is the largest before they start to use fans for cooling which can be quite noisy. User replacing the battery is very simple, though would void the warranty obviously.

One nice thing is that you can use them as a mains power battery power pack. They don't require being connected to active mains power before providing power to their sockets. Has been handy in a couple of situations for things that aren't USB powered. They will beep every 30 seconds or so while on battery.

Dimensions are 148H x 100W x 288D but the power cable at the back adds another 50mm to the depth. No in-built network based monitoring but it has a USB port for monitoring which is compatible with NUT. I plug it into a Raspberry Pi to monitor it on my network. Adding a USB cable would add extra depth to the above as that plugs in at the front. Would highly recommend getting a UPS with a USB port for monitoring with NUT if no native network monitoring. Can feed into many different systems.

Paul1977

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#2725374 11-Jun-2021 15:29

@littlehead good idea about using a Raspberry Pi to monitor and manage.

I just came across this PowerSheild one which would physically be perfect as it's short enough to fit in my wall cabinet. I can get it for considerably cheaper than that list price, but is still it's still expensive for the capacity. And I'd have to do my calculations to see if it's powerful enough. It's a perfect form factor, but I don't understand why the price is so much higher than a similar tower model.

Paul1977

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#2725376 11-Jun-2021 15:33

Rikkitic:

Maybe this will help:

In an AC circuit, power and VA mean the same thing only when there is no reactance . Reactance is introduced when a circuit contains an inductor or capacitor . Because most AC circuits contain reactance, the VA figure is greater than the actual dissipated or delivered power in watts. This can cause confusion in specifications for power supplies. For example, a supply might be rated at 600 VA. This does not mean it can deliver 600 watts, unless the equipment is reactance-free. In real life, the true wattage rating of a power supply is 1/2 to 2/3 of the VA rating.

When purchasing a power source such as an uninterruptible power supply ( UPS ) for use with electronic equipment (including computers, monitors, and other peripherals), be sure the VA specifications for the equipment are used when determining the minimum ratings for the power supply. The VA figure is nominally 1.67 times (167 percent of) the power consumption in watts. Alternatively, you can multiply the VA rating of the power supply by 0.6 (60 percent) to get a good idea of its power-delivering capability in watts.

Think of watts as DC power and VA as AC. For some things they will be essentially the same. With a wall wart or other adapter or power supply, VA refers to the power being drawn from the source, while watts refers to the power available to the device. Wherever you see VA mentioned, use that as your power figure. Otherwise use the watts one.

(If you are feeding any of your devices directly with DC from the UPS, the watt figure applies. If you are supplying mains voltage to anything, use the VA one.

(I have a Constant Vigil Sentry Lite that supplies DC to my router and ATA. You can order it with any voltages you need but it probably wouldn't have enough capacity for your requirements. It is a great little unit though and works well for me.)

Thanks. Would still be easier if they could just use one measurement!

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Paul1977

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#2725381 11-Jun-2021 15:41

@littlehead just looked up the Eaton 5E range, not rackmount but nice and compact - and certainly better value.

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#2853439 19-Jan-2022 13:32

Apologies for the thread necromancy...

Have a similar question, but only need to drive:

ONT
Ubiquity USG
Ubiquity PoE switch drawing 15w

So perhaps all up 20-25W.

How long would a 1000VA / 600W unit expect to run for. Is the maths just 600/25 = 24h? Or is there something special needed to calculate watt hours etc?

mkissin

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#2853454 19-Jan-2022 13:36

Unfortunately not. At powers that low, the inefficiency of the UPS unit itself will be your biggest load, and likely limit runtime to 3 or 4 hours. Some units will spec an unloaded runtime, if you can find data.

mkissin

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#2853457 19-Jan-2022 13:44

By way of example, take this UPS: APC Back-UPS CS 350VA, 230V, 4 IEC outlets (1 surge) - APC New Zealand

It's listed as 210W/350VA, but the battery is only 12V, 7AH, so nominally 84 WHr of energy.

25W you might expect to run for (84/25=) 3.4 hrs, but the runtime graph shows you'll actually get about 49 minutes. That's the UPS itself eating the remaining power (among some other real world stuff)

insane

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#2853459 19-Jan-2022 13:54

Right, fair points, so the ups and inverter inefficiency comes into play.

Would like to get ~ 8-12 hours of runtime (as long as our laptops possibly could run on battery).

Have an all day power cut coming up thanks to Vector and don't want to go into the office if I can avoid it. Have been wanting to do this for a while as and is a large enough motivator.

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mkissin

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#2853464 19-Jan-2022 13:57

There's no way you're going to get anywhere near that unless you either buy a huge unit with external battery packs available ($$$$) or start rigging up your own external batteries. That's definitely a path you could go down, there's a ton of how-to info around on the net.

Edit: my actual recommendation would be to buy a messed up old Nissan Leaf. 12 hours of runtime off that battery pack, no worries. That's what I do.

Jase2985

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#2853466 19-Jan-2022 14:02

would something like a constant vigil sentry lite (would need 2 for 3 devices) do the trick? you select your battery size. That is on the basis that all the devices use the same input power.

1101

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#2853467 19-Jan-2022 14:02

Factor in

as it ages , batt capacity & runtime gets less . Ive seen plenty of small UPS's that do nothing at power cut (old batts)

cheapies have slower switching time , so might not switch fast enough & MIGHT get some connected devices re-powering up after the UPS kicks in .

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#2853474 19-Jan-2022 14:13

Hmm, OK so might scour TM for a small second-hand petrol generator then. Would also be able to power our computers and screens if we needed.

I like the nissan leaf idea! Have a good friend who has one, and my wife thinks we should consider one or another EV too.

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