UPS run time Calculation
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I think I've got it right, but just want to confirm before ordering more UPS boxes.
QUESTION: How long will the example UPS support the example load? For the example I'm using the following specs for an APC 1500VA UPS box: VoltAmps: ? ?1500 VA
Voltage: ? ? ? ?120 VAC Load: ? ? ? ?6 amps or 720 watts (6 x 120) First I have to calculate AmpHours, which are not stated anywhere in my APC 1500 specs, using the following formula: VA divided by V = AH 1500 VA / 120 VAC = 12.5 AH Next I need to calculate how long the above example load can be supported by this sized UPS using the following formula:
AmpHours x Voltage divided by Load (watts) = ?Runtime (hours) 12.5 VA ?x 120 VAC / 720 W = ?2 (hours) ?
So the answer to my question then is about 2 hours, right?
Am I doing my math right? Are my formulas correct? 2 hours sounds about right for this size (1500 VA) UPS with a 6 amp load, but at the same time it's a little disappointing. TIA,
John ? |
开云体育On Nov 12, 2024, at 12:58?PM, Roger Moffat via groups.io <rogerkiwi@...> wrote:
Okay. That makes sense, but I'm still running the numbers and I'm doing something wrong. I'm trying to solve for the variable of "Time" in hours or minutes given the below specs.? For the example I'm using the following specs for an APC 1500VA UPS box: VoltAmps: ? ?1500 VA Voltage: ? ? ? ?120 VAC Load: ? ? ? ?6 amps or 720 watts (6 x 120) First, don't I have to calculate AmpHours, which are not stated anywhere in my APC 1500 specs, using the following formula: VA divided by V = AH ?(as indicated in the screenshot below)? 1500 VA / 120 VAC = 12.5 AH Is this where I'm going wrong? Your above formula of VA / V = A does not address the AmpHour equation, right?? Sorry, my head is spinning now. This should be so simple but I need to walk away for a moment and revisit. Is it not possible to calculate AmpHours?? I was using the below formula from an AI search. Cheers, John? ?? ? ? ? ? ?? ?? ? ? ?? ? |
开云体育John, a UPS is not intended to run equipment any longer than it takes to nicely save your work and safely shut down.?Even if you figure how much power you have, how do you calculate the drain of power. So, unless you are in a critical backup, I would save and shutdown.? A generator and switching gear is needed to continue running, but you may not have an internet connection.? On my iPhone Xr On Nov 12, 2024, at 09:35, John via groups.io <OceanCity@...> wrote:
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开云体育On Nov 12, 2024, at 2:31?PM, Brent via groups.io <whodo678@...> wrote:
Yup. I totally understand and agree. You know me. Always looking to have my cake and eat it too. In this case I'm looking at our hydronic heating system to accomplish two goals: 1) One UPS to protect the control computer from any spikes, surges, brownouts, micro outrages, and even short power outrages. This is critical because the controller costs a fortune, is totally electronic and thereby subject to any of the above damage, and if it had to be replaced would take days. This could be catastrophic if it had to be replaced during an extended cold-freeze. ?I would have to order it and get it delivered fast, then it would take at least a day to wire the new unit and configure it, assuming they still make it and it's in stock. ? 2) A second UPS, on a separate floor of the building, two floors down at ground level, again, to protect the control pump electronics from any spikes, surges, brownouts, micro outrages, and even keep half a dozen circulator pumps running. My guess is not very long at all, and in the end I'll just leave it at that, although it wouldn't hurt to throw in the later UPS for the sake of protecting the electronics on all the circulator pumps.? I was just curious how long, knowing the load, and the voltage, approximately 6 amps max at 120 VAC, a 1500VAC UPS would run before depleting. That's all. Just a rough estimate. Am I looking at minutes, an hour, two hours? ?The boiler runs on natural gas, so if the power were to go out the UPS would keep the pumps running, but I doubt for very long. Back to your response, totally agree, totally understand. ?I was even looking into those Tesla "whole-house" batteries, but the cost a small fortune and I can't justify that level of protection at that cost.? Cheers, John? |
开云体育Ok, that puts a different light on your original question, but not much.First, the Hydronic Controller is just a specialized computer, so yes it needs a surge protector or device to clean up the power. I almost included a bit about not trying to run a laser printer from a UPS, as a single laser printer draws way too much power, more like an electric motor or refrigeration compressor. Your hydronic system has multiple electric pumps. I would assume in the middle of winter, all the pumps run 24/7. I don’t even have a clue if the pumps are low voltage or 120v.? I would talk to a hydronic installer or designer about what you should install. Don’t reinvent the wheel, I am sure they have already have a good list of questions and answers for this issue. I think his answer would be for a short outage, to just ride it out. For a longer outage, I think he would suggest a backup generator, not a residential UPS. They should be able to tell you how long before a system cools down according to a guesstimate of your insulation value. I am not in any way an expert, and I would ask for info on how he would do the calculation. A backup generator would give you heat, light and refrigeration in an expended outage.? I was just chatting with a friend in northern Idaho, whose lives on a small farm. He is not a preppier, the farm is large enough to feed him and his wife, and swap a couple of lambs for beef. I think a small backup generator for him would start at $1500 if he did some of the work and swapped labor. But then again, he heats an earth home, barn with animals and shed with wood. An upgraded system would be more like $3000 and up.? Brent ?
On my Mac mini running 10.15.7?
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Since I brought it up, there are 3 things to avoid plugging into your UPS, laser printer (as opposed to ink jet), refrigeration or a/c compressors, and electric motors. All of these items have a huge draw when starting up and can cause a power surge.? If, for example, you plug a laser printer into a UPS along with a computer, display or other delicate electronics, you can cause a power surge on the protected side of any voltage filter that the unit may have. Even plugging them into the same circuit should be avoided, if it can be reasonably avoided. Brent ? On my Mac mini running 10.15.7? |
开云体育On Nov 12, 2024, at 7:47?PM, Brent via groups.io <whodo678@...> wrote:
Interesting new thought I never considered, yet makes for a ?complete inconvenient consideration. ? I'm just tinkering with ideas at the moment.? The real goal here is to protect the controller. That's it.? I fully realize it's just not realistic to expect any more than a few matter of minutes, or an hour at the most in terms of backup battery power. I guess what I'm really looking at is the "power conditioning" side of a UPS, not it's ability to supply power for an extended period of time. Cheers, John? |
开云体育Thank you everyone for your comments, suggestions, and support. I appreciate it. I don't really care how long the UPS boxes will last as long as they protect the electronics in our hydronic heating system from micro outages, surges, brownouts, etc., for more than a few minutes at the most. The power coming into our city is all underground, backed up three times what's needed in case one goes bad, and we have no trees to fall, so full-out outages are a rarity and if they do occur they never last longer than a few seconds or minutes. ? As for my computers, modem, router, switches, basestations, etc. they are all wired via USB cables to several UPS boxes and I have the system prefs in the computers and in my NAS boxes to shut down after certain perimeters have been reached as the UPS batteries discharge. If triggered, then a "Proper" graceful automatic shut down will occur to prevent any physical or data damage. So I've got about half a dozen APC UPS boxes total.? So, I'm more than comfortable with the levels of power conditioning and level of UPS backup capacity.? I was really just asking about the math formulas out of curiosity, that's all.? Again, a million thanks for your support.? All the best, My humble home office. I trade stocks all day. New Tekmar Hydronic Controller which I installed about a year ago, controls all the circulator pumps in the next photo, below. Boiler room on ground floor.? ? ? ? ?? ?? ? ?? ? ?? |
John
Brent