Having power during power cuts

Hermanus

Member
Where I live we have very unreliable power because of 4-8 hours downtime due to load shedding. I want to install backup power to keep going during those downtimes. I am considering to do it in two phases.

Firstly I want to install an inverter that would supply power to critical circuits during a power failure. I am thinking of installing an inverter to supply power to lights, computers and cell phone chargers (critical low consumption components).

As a next phase I want to add a generator to the system to have a more complete solution. I see this as a future nice to have.

For the first (inverter) phase of the project I am not sure what to use for a cutover switch. Something that won’t reboot computer when the power change from grid to inverter power is important. Secondly, there must be something in place that would prevent me from using the stove, geyser, under floor heating, etc (heavy consumption units) when it’s on inverter power.

I am sure there are some cool solutions to do this. Thanks for your time.
 
For your first Phase, I'd simply suggest one or more reasonably large UPS units. UPS's are a battery and inverter built into one box.... something like this maybe:

http://www.pcmall.com/pcmall/shop/detail.a...ackup%20Devices

That should be enough to power a cell phone charger for days or a small computer for an hour or two. You can get bigger ones that will last longer, and/or divide your load up on several UPS's. These UPS's can just be installed under the computer desk and will automatically cut over when the power fails so you don't have to worry about restarting your computer or anything.

Lights are the tricky part, because they tend to be very power hungry... particularly incandescent lights. If you can convert the lights you want to run to compact fluorescent I think you'll go a long way toward getting lights on your UPS as well.

Depending on how much you want to spend you could also get a UPS like this...

http://www.pcmall.com/pcmall/shop/detail.a...ackup%20Devices

Something like that could be installed with it's own load center and you could put several circuits on it including lights (although I'd still suggest CF bulbs). That would take a bit of work from an electrician to install and you'd need a large place to put it, preferably in the basement or on a concrete slab as UPS's like that can easily weigh upwards of 800 or 1000 pounds.

Frankly, though, if you're going to be spending that much on a UPS I'd suggest getting a couple of smaller UPS's for the computer and maybe the TV, then get a generator for everything else. The power a generator provides can last indefinitely (as long as it has fuel), but a UPS only has a finite runtime... and I think the cost of a generator and a larger UPS would be similar.

HTH,
Brett
 
There are "off the shelf" switch systems that you can mount beside your breaker box so only "select" breakers can be wired to say an external generator feed.

I didn't have a lot of time to check this out, but have a look at THIS.
 
That should be enough to power a cell phone charger for days or a small computer for an hour or two.
HTH,
Brett

I don't think a computer UPS will run for "days" regardless of how light a load you have on it. They are built for minutes or sometimes an hour or two but not days.

Also I would be concerned about larger battery inverters or even large UPSs as there are ozone and sometimes even hydrogen gas issues to deal with. I tried to replace my 625VA office UPC with a 1200VA model yesterday and hadd to take it back out because of the strong ozone smell it gave off when charging. (I got a silent fanless model so the smell did not just disperse).

Any battery charging arrangement of any significant size needs careful thought with respect to venting and air flow.
 
I don't think a computer UPS will run for "days" regardless of how light a load you have on it. They are built for minutes or sometimes an hour or two but not days.
hehe... perhaps that might be a bit of an overstatement, but I have had 1500VA ones last for many hours with a light load... but days is probably pushing it.
Also I would be concerned about larger battery inverters or even large UPSs as there are ozone and sometimes even hydrogen gas issues to deal with. I tried to replace my 625VA office UPC with a 1200VA model yesterday and hadd to take it back out because of the strong ozone smell it gave off when charging. (I got a silent fanless model so the smell did not just disperse).
Any battery charging arrangement of any significant size needs careful thought with respect to venting and air flow.

I think something was wrong with your UPS then. A properly functioning UPS shouldn't create ozone or any gas or smell. The fan in many larger UPS's is for cooling... not to disperse any gasses. The batteries should all be sealed and shouldn't vent any hydrogen gas or anything else.

Brett
 
I don't think a computer UPS will run for "days" regardless of how light a load you have on it. They are built for minutes or sometimes an hour or two but not days.
hehe... perhaps that might be a bit of an overstatement, but I have had 1500VA ones last for many hours with a light load... but days is probably pushing it.
Also I would be concerned about larger battery inverters or even large UPSs as there are ozone and sometimes even hydrogen gas issues to deal with. I tried to replace my 625VA office UPC with a 1200VA model yesterday and hadd to take it back out because of the strong ozone smell it gave off when charging. (I got a silent fanless model so the smell did not just disperse).
Any battery charging arrangement of any significant size needs careful thought with respect to venting and air flow.

I think something was wrong with your UPS then. A properly functioning UPS shouldn't create ozone or any gas or smell. The fan in many larger UPS's is for cooling... not to disperse any gasses. The batteries should all be sealed and shouldn't vent any hydrogen gas or anything else.

Brett

The smell was not coming from the batteries but from the inverter. Maybe it was not ozone but merely the "burn-in" smell of a new device getting hot for the first time. A cooling fan might have dispersed the smell somewhat and made it less noticable but these are convection cooled (I am very sensitive to fan noise and will not allow fans in my office). Maybe the smell will stop after a few days and I can move the unit back. I know the new APC units have a similiar issue with burn in odors and their forum says it can last a week or more on new units.

In any case, I am just suggesting that you might want to think about where you are going to locate any sizeable battery charging setup.
 
During the 3 day power outage that happened a few years ago, I Ran 1 very important server for 2 1/2 days off of 2 UPS units.

Both UPS units had been Tripplite 5000VA models with 2 battery packs each.

That was the most I have run UPS units, and I have run those same UPS units for hours with a few servers during other outages.

Of course these UPS units are a bit expensive.

StevenE.
 
Due to the size loads you are desiring to keep powered, and the length of time you are talking about, I think a generator backup is really the only plausable solution. It certainly won't be cheap, but it should do everything you want. Trying to put together a bank of UPS devices is just going to be a frustrating and costly experience IMHO. Better to put that money towards the cost of the generator and do it right the first time.
 
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