Power outage options - Connect Generator to a UPS

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per0w

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#314954 2-Jun-2024 09:55

Hey Guys,

Just looking at a cost effective solution to cover the half dozen power outages we get over the winter months. Some range from a few hours to a couple of days(always at the most inconvenient time).

I've got a small rack mounted setup at home, ONT, Router, 24port POE switch, dell desktop, Synology NAS. I worked out the idling wattage to be approx 130watts.

I was thinking of buying the PowerShield PSDR800 Defender Rackmount 800VA (480W) Line Interactive UPS or Dynamix UPSD1600 Defender 1600VA (960W) Line Interactive UPS. This would give me 10-20mins or so to then run a generator and connect it up..

My question is has anyone got a setup similar? UPS to handle the instant power outage and then giving you enough time to then crank a generator over and run the network etc without any outage?

Also, what Generators would be ideal to connecting up to the UPS(if that is possible)?
I'd also use the Generator to power a fridge/freezer. and charge the odd phone/ipad.

cheers

Dynamic

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#3243641 2-Jun-2024 10:51

I have some experience with this, though limited.

HP UPS. Cheap noisy petrol generator with a relatively dirty output resulted in the UPS rapidly switching in and out. Research showed I needed a generator-comparable UPS (which I think means one that is less fussy about its input.). Switched to a digital inverter generator and it behaved beautifully.

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Dynamic

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#3243642 2-Jun-2024 10:52

Note that when powered directly by the cheap generator all my electronics behaved fine. It’s just the UPS that was unhappy.

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richms

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#3243653 2-Jun-2024 12:11

What I found would happen with a non regenerating UPS is that it would see the mains power there, switch to it and the generator would immediatly slow down so the UPS would switch back to battery. When it slowed down from that UPS connecting, then one of the others that might have finally settled down and being ok with the power would switch to battery. It was a mess with the UPS's all swtiching back and forth and the generator speeding up and slowing down constantly as the throttle tried to match the vastly changing load.

Second generator was an inverter one, and it was more sucessful but the voltage would still sag as the UPS's cut over, so I had to run it with the economy mode that would let the engine speed change to match load turned off till all the UPSs were happy and then I could turn that on.

Suggestion would be to get one larger UPS rather than many small ones and dont try to run the fridge off the same generaor.

Richard rich.ms

SomeoneSomewhere

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#3243770 2-Jun-2024 14:05

Many UPSs have adjustable sensitivity for what is 'acceptable' power quality. When using smaller generators, you will likely need to set this to be more forgiving of low mains voltage and frequency variation.

Most electronics, especially lower-power stuff like network switches and routers, are very forgiving of power variations. Server PSUs can be a lot more finicky.

CMTechNZ

12 posts

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#3244643 5-Jun-2024 10:38

Although not the cheapest, I'd recommend a Honda EU70iS inverter generator, especially if your looking to run appliances like a fridge with high start current. They are quiet, ramp up and down as load changes (more quiet when low load) and work well with UPS's. Have used these to keep commercial premises running (except AC/water heating) for days due to line faults. Have many rural clients with these as a whole house backup (again excluding high load appliances) during power outage. Most have it able to be plugged in with a permanent changeover switch.

FailedWOF

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#3256796 5-Jul-2024 23:09

I've been considering this for the same scenario: https://www.prolineindustrial.co.nz/product/gt-power-gt4000i-lpg-electric-start-inverter-generator

It ticks all the boxes - digital inverter for clean sine wave output to the UPS, runs off LPG so no stale petrol/diesel to worry about, 15A socket with 3.5kW continuous output for my 3kVA UPS, auto start.

What I haven't found yet is a reasonably priced automatic transfer switch that supports 2-wire start...

CMTechNZ

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#3257030 6-Jul-2024 21:56

Those specs look good for the price. The equivalent Honda generator would be double the price. If possible I would test it with your UPS as I've seen 5kW inverter generators fall over trying to power a 3kW UPS as they can't handle a high percentage of capacitive load.

For the ATS the lowest cost option could be using contactors with something like a custom Arduino/Pi/Cheap PLC for control as commercial ATS's can be cost prohibitive.

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BlueOwl

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#3257071 7-Jul-2024 10:24

We've got the Dynamix UPSD1200 and cheapo 2kW generator from Bunnings. This works well, but could be improved. We power computer and WiFi gear off the UPS and cable it into the generator when the power goes out and we think it will be for an hour or more. Stuff like fridges (2x) and freezer connect direct to generator, microwave oven connects direct to generator - but has quite a load which you can hear the generator revving up when stuff like fridges and microwave come on.

So far our record power outage was 2.5 weeks (Feb 2023), and we learned a lot from that one. For a start, a generator running continuously is really annoying - even when it's a fairly small one and 30m away from the house.

A friend dropped off their Ecoflow kit a few days before power was restored - and it was a wonder to behold. They'd splashed out and got the biggest battery pack I'd ever seen with the generator and solar panel to keep it topped up. The Ecoflow generator was auto-starting to charge the battery pack and only ran for about 30mins per 24hours. This used MUCH less fuel than our cheap one (about 0.5 litres/24 hours as opposed to 12 litres/24 hours) and didn't have the noise nuisance 24x7. This kit ran our fridges, microwave, lighting and (via the UPS) all computer and Wifi gear, but is expensive.

Some things to consider:

don't connect electronic devices to a cheap generator output which has inductive loads on it. I lost a Draytek router doing that
more expensive and inverter generators really are better
consider cost, storage, and lifetime of fuel
having charged devices, internet, cold beer, hot food, and lighting during a multi-day power cut is a big psychological win
sitting in the dark and having to trash the defrosted contents of your freezer is a big psychological loss