So Im maxing out a UPS. all the machines are close. Do I parallel the power or serialize it or both. I Can afford a few $500 UPS over a $3k commersial unit… How to share power …
measure and divide or bank and bank ?
With serializing you mean put multiple UPSes behind each other? Then you would still max out the first UPS.
You can put them in parallel (if your outlets and breakers can handle that), measure what goes where, divide and conquer.
Never EVER parallel UPS’s! Divide the load among them, but never on the same circuit!
Having said that, you can add battery banks to certain types/brand/models of UPS. Expensive, but not enough if the load is too high already.
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Unless you got two different sub-stations feeding your servers, current-constraints on the breakers aside, I don’t see how this would be horribly bad. Maybe I am missing something here?
Yes. It’s called a feedback-loop but if you’re not into electronics I don’t expect anyone to know about it. I’ll try to explain:
Image being in the shower, the old type where you have to regulate temperature manually by turning the hot and cold water taps yourself. What you have is a feedback loop: you control the flow and thus gives feedback to the controls (taps). Now someone adds another running hot water shower head into your stall. There’s nothing you can do about it, except adjust temps in your own stall. What happens? You’d basically shut off the hot water in your stall and have to adjust the amount of cold water to compensate for the external stream of hot water coming in.
With electrons it’s the same thing but much, much faster. No two UPS’s are exactly the same, even if they have successive serial numbers from the factory. So the sine wave they output will never be exactly the same either, for amplitude and phasing. Connecting both outputs adds considerable currents between them through the wiring, which may lead to fire. That’s why each UPS must have it’s own output circuit.
HTH!
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Oh-kay, now I get it.
Paralleling them on the AC-out would be bad unless specifically designed for that (special) use case. That is ignoring the fact you would need a plug-plug forbidden power cord.
Common case would be two UPS hanging on the same breaker, feeding two different PDUs/socket strips and those hanging on two PSUs in each server/switch.
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Depends…
For anything with a redundant power supply, split it across a pair of UPS.
Add additional devices to each being mindful of total load.
If you have a mission critical server (probably a file server) you need to ensure they are communicating and can receive a signal to write out the data and spin down in the event of power loss.
I also split based on need / want.
My current housing precludes a generator option so there are:
UPS’ for servers
UPS for networking
UPS for WiFi
UPS for workstations
UPS for fridge
UPS for every computer in every room of the house (a lot)
and 2 more with light loads for failover during an extended outage.
Thats what I meant, thanks for making it clear. Combining the output of two UPSes would have meant creating your own cables or distribution box. And doing that is a big no no if you don’t have the certification for this. And as @Dutch_Master has shown, with the certification you wouldn’t do this.
Don’t play with mains power!
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Well my bad. the time to shut down everything is growing smaller, hell the betteries in the old arse UPS are in need of replacing. thats another thread !
What I was was wondering time wise and sync wise… Would be easy to bank the UPS 10 mins and 10 mins etc but them fake waves. I feared… Balancing will be hardner
Connecting both outputs adds considerable currents between them through the wiring, which may lead to fire.
What do you mean connecting the outputs? Is it that setting:
- UPS A plugged on outlet A
- UPS B plugged on outlet B (or A if anyone feeling cold)
- use a special cable that would merge an output of UPS A and an output of UPS B to plug it in a single consumer
(I would not even dare to attempt that)
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Im thinking the old UPS batterys could use replacing. Kill-O-Watt meter measuring atm.
Maybe buy a new UPS bigger and retrofit new batteries in the old one and stagger upgrading batteries 4-5 years apart.
The whole keeping the uptime up by daisy chaining (serial was ezy mode). But UPS use generated sine waves vs the grid… I though about it.
I should be an engineer more and test more I guess. Not ask for an answer.
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