Generators + electronics...

  • Active since 1995, Hearth.com is THE place on the internet for free information and advice about wood stoves, pellet stoves and other energy saving equipment.

    We strive to provide opinions, articles, discussions and history related to Hearth Products and in a more general sense, energy issues.

    We promote the EFFICIENT, RESPONSIBLE, CLEAN and SAFE use of all fuels, whether renewable or fossil.
Status
Not open for further replies.

madge69

Member
Nov 18, 2010
67
central ma
There's a lot of misinformation out there regarding generators, UPS', sine waves, etc. I'd just like to clarify some things. First, in general, generators and UPS' do not get along nicely. Most low-end UPS' are so-called "standby" or "backup" UPS' in that their inverters are not running all the time. The rest of the time, they just pass the utility voltage right on through to the connected equipment (perhaps with some conditioning of the voltage). This type of arrangement with a typically underpowered generator (<10kW) and a standby UPS will cause the UPS to cycle from line to battery repeatedly until the battery dies, all while creating lots of noise on the AC side. (If you do get it to sync, it would be like connecting your equipment directly to the gennie with a power conditioner in between).

One solution to this problem is to use an oversized generator (>10kW). This means $$$$$$$$$$$ which a lot of us don't have. So we go out and do the best we can with what we have and that's likely a cheaper construction-grade generator, maybe around 5-7kW and about $500-$1000. That'll run just about everything you need it to in most houses, except for the well pump if applicable. And remember this generator will put out DIRTY AC that's poorly regulated (think +/- 3Hz on frequency) and have lots of harmonic voltage distortion. This is OK for most things except sensitive electronics.

Which brings us back to UPS'. The type of UPS you need to run off a generator is what is called an "online" or "double-conversion" UPS. This type of UPS always converts the incoming AC to DC then back to true 120V / 60Hz AC. THIS IS THE ONLY WAY TO CORRECT FREQUENCY. These units are not cheap as you may have imagined.

I have one of these (APC SURTA1500XL):

http://www.apc.com/resource/include/techspec_index.cfm?base_sku=SURTA1500XL

That I use for the bulk of the electronics I use off the generator including TV, DVR, PC, receiver, etc. I bought this after the ice storm of 2008 that knocked power out for eight days. It cost roughly $1000.

I also have one of these (CyberPower OL1000RMXL2U):

http://www.cyberpowersystems.com/products/ups-systems/smart-app-ups/paragon-series/OL1000RMXL2U.html

That I used for the pellet stove. I figured same type topology of UPS, significantly cheaper...should be good, right?

After going through two days without utility power, but with a backup generator (http://www.homelite.com/catalog/generators/HG5700), I can say that the APC unit is built to a much higher standard (and it costs more too unfortunately). The TV and everything worked flawlessly with the APC, but after two days of running the pellet stove off the CyberPower, I could hear the motors sounding differently. I'm now purchasing an additional APC SURTA1500XL exclusively for the pellet stove and I'll move the CyberPower for a different use.

Remember that this type of UPS ALWAYS regenerates the true 120V / 60Hz that is needed for its output and ALWAYS accepts whatever crappy AC you feed it on the input. And it'll also run your equipment off battery for awhile if you lose all power...

I also have to throw in a warning that if you connect a generator to a building's wiring, you MUST use a transfer switch or you could face extensive fines or even kill a line worker.
 
Good write up
 
Thanks for the great info. I hooked my XXV up to the generator through a small UPS. The APC ES 750. Its just a back-up. The stove didn't run quite right but I don't think I did any damage.
 
I hook my gen up to the oil burner. i don't have to worry about burning up any electronics that way.cheaper burning up a couple gals of oil than the stove controls.
 
urkiddin said:
I hook my gen up to the oil burner. i don't have to worry about burning up any electronics that way.cheaper burning up a couple gals of oil than the stove controls.

Yes, but then you're not using a pellet stove and where is the fun in THAT???? :)
 
Thas that mean i can forget about running my 'puter,pellet stove & tv with just a straight connect to my whatcha macallit thats connected to my whatcha macallit without buying an expensive whacha macallit ? No plug & forget ?
 
Nice write up but, WOW the price tag,there have got to be a cheaper solution.
 
muss said:
Thas that mean i can forget about running my 'puter,pellet stove & tv with just a straight connect to my whatcha macallit thats connected to my whatcha macallit without buying an expensive whacha macallit ? No plug & forget ?

I agree completely.
 
cold front said:
Nice write up but, WOW the price tag,there have got to be a cheaper solution.

One would think. We didn't have a choice on the gennie we got. It was during the ice storm, we needed one, it was available, and they were going to sell out in minutes.

That said, if I was smart and planning ahead and looking at a standby generator such as a Guardian or whatever, would I really trust it enough to plug my expensive electronics directly into it or would I also want the UPS in that situation? I would want a UPS for the added peace of mind...

I just looked at standby generators and they look like they're about $3000 plus installation, depending on your needs. Please correct me if I'm wrong... I'm starting a well pump over 400' down...it shakes the little 5700 watt gennie we have... As someone else said recently on this forum, there are no shortcuts when it comes to power generation.
 
The money you're talking for the high price "cleaner" would have bought a higher powered, cleaner current, standby generator that would have done the job for your whole house.
 
madge69 said:
.....That said, if I was smart and planning ahead and looking at a standby generator such as a Guardian or whatever, would I really trust it enough to plug my expensive electronics directly into it or would I also want the UPS in that situation?......

My whole house Generac 12Kw unit ran my pellet stove exactly the same as utility power....I did not notice anything different, and that was for 25 hours straight. No UPS used.
 
There is always a lot to consider. I made my decision based on how often I may use my backup. The UPS is maybe a second tier brand, basic purpose is to run pellet stove until genny is running, and it worked pefectly during the very brief power outages we just had..saved me a bit of a headache. I could have gone higher end but for the most part it is just a surge protector.

And for my generator it is the cheapest inverter I could find that would power my sump pump or fridge, or pellet stove and entertainment. Considering it will only be used to get us through the rare (hopefully) short (hopefully) power outage it didn't make sense for me to go high end for it will most likely get very little use.

I would perhaps buy a bigger non-inverter generator to give me the peace of mind to run some other things but I have not been able to convince myself it will ever get used...
 
As I mentioned in another thread, my mom was or is in the process of getting a whole house standby installed. The company recommended a 14kw Generac so that is what she's getting. Total cost with install, concrete pads by owner, LP tanks, etc is about $6500. This is turn key ready for power outage.
 
Well I learned a lot from this post, and unfortunately my generator doesn't put out as clean of power as I would like.

Ugh, time to look into buying a 10KW Generac.

SWMBO won't be happy about having to purchase that.
 
Ha ha, my wife told me to GTFO.
 
urkiddin said:
I hook my gen up to the oil burner. i don't have to worry about burning up any electronics that way.cheaper burning up a couple gals of oil than the stove controls.

My thoughts exactly!
 
MrOletta said:
Ha ha, my wife told me to GTFO.

http://www.northerntool.com/shop/tools/category_powerhorse+generators+portable-generators
^&^^ up to 9000w surge 7250 running @ ;ess that 5% thd. (though on the forum discussion i link below, it's said to think of it as a 5500w unit if you want to run it continuous and have it last.)
http://www.northerntool.com/shop/tools/product_200419022_200419022
at $299 with the same thd ratings, you could run just the sensitive stuff off of the ph 2200.

i liked the discussion on this forum-
http://www.mytractorforum.com/showthread.php?t=120067
pretty much a bunch of hardcore folks who prefer the very best equipment. (one call it a piece of junk.)
and they still say some good things about the motor.
i guess watching the oil is key for long runs.
that and running it periodically with a load. (got an social email from our lawyer in new jersey describing folks whose long stored gennys weren't working when they busted them out after the storm)

after reading more from folks here, i'm reasonably confident that less than 5% thd is good.
i also heard you should use premium fuel and one person said to add seafoam gas treatment.
i'm thinking if i take optimum care of the ph2200 i plan on buying, it will last me.
it does have a 2 year warranty and there are northern tools stores here in maine.

$299 + $74 shipping (amazon) still comes in at $70 less than the chinese generac ix1600. which has horrible reviews. (unlike their top of the line models)
and having 1800w gives me 200w more than the generac i almost bought would have.


not trying to be a salesman. just thought i'd share what i came up with while being on a budget.
 
hossthehermit said:
The money you're talking for the high price "cleaner" would have bought a higher powered, cleaner current, standby generator that would have done the job for your whole house.

True. Hindsight is wonderful, but when your house is 50 degrees with no heat or anything and you have to drive an hour just to find a gennie in stock, you take what you can get.
 
Xena said:
So a "pure sinewave UPS" like this one
only delivers a pure sinewave when running under
battery power?
http://www.cyberpowersystems.com/products/ups-systems/adaptive-sinewave-series/CP1350PFCLCD.html

It's a so called line interactive UPS meaning if the supplied voltage and frequency falls within a specified range, it will attempt to sync to mains. This causes a disturbance on the ac line which causes the ups to switch back to battery. One the ac stabilizes, it will attempt to switch again, repeating the cycle ad nauseum. If it does manage to sync to the crappy gennies output, it's basically passing the crappy ac right through, perhaps with some attempt at noise suppression and voltage regulation, but nothing can be done about the frequency if it is wrong.
 
madge69 said:
Xena said:
So a "pure sinewave UPS" like this one
only delivers a pure sinewave when running under
battery power?
http://www.cyberpowersystems.com/products/ups-systems/adaptive-sinewave-series/CP1350PFCLCD.html

It's a so called line interactive UPS meaning if the supplied voltage and frequency falls within a specified range, it will attempt to sync to mains. This causes a disturbance on the ac line which causes the ups to switch back to battery. One the ac stabilizes, it will attempt to switch again, repeating the cycle ad nauseum. If it does manage to sync to the crappy gennies output, it's basically passing the crappy ac right through, perhaps with some attempt at noise suppression and voltage regulation, but nothing can be done about the frequency if it is wrong.

It is more suited to give you time to hook up the generator or give you time to shut the stove down properly. If the generator gives you dirty power ( outside the range of whichever setting you have on ) it will switch to battery..that is how it "cleans" the power. If the generator is out of the range specified for too long the battery will eventually die.
Maybe this weekend I will hook up my cheap inverter generator to see how the UPS reacts. You can use it to see the fluctuations in current.
 
So...I have a question for all of you. Batteries are like a filter of sorts really cleaning up noise in the telcom world (and back up too)... what if I were to hook my genny that doesnt have a clean sine, to a battery charger, to a battery, to an inverter and connect that to my stove? I know its kind of a pain but wouldnt that clean up the power. the battery would(should) take care of any fluctuations in surge and also clean up any noise that the blowers/boards might not like.........just a thought?!?
 
watrskir said:
So...I have a question for all of you. Batteries are like a filter of sorts really cleaning up noise in the telcom world (and back up too)... what if I were to hook my genny that doesnt have a clean sine, to a battery charger, to a battery, to an inverter and connect that to my stove? I know its kind of a pain but wouldnt that clean up the power. the battery would(should) take care of any fluctuations in surge and also clean up any noise that the blowers/boards might not like.........just a thought?!?

What you're describing is basically building an online UPS from scratch. It would accomplish the same thing, but I think if you really looked into the components that are required, it might be cheaper to just buy an online UPS. The gotcha in the case you describe is the inverter itself. It would need to be UL (458 I think?) listed for permanent installation to a building's wiring. This unit would work, but is over $1000: http://www.xantrex.com/power-products/inverter-chargers/prosine-2.aspx. For long term use, you'd need true deep cycle batteries from a company such as http://www.trojanbattery.com/Index.aspx I actually own a couple of Trojan T-105's that I purchased in 2008...if I recall each one of the batteries is roughly $400 and you need to just to make 12V. I believe that inverter I identified above would require a 48V battery bank at a minimum.
 
That is essentially what the expensive units do. These are called the Double-Conversion or Online UPS systems. They have a high end inverter that generates clean power and a charger that is rated for a higher usage than what would be used by the inverter. This way the battery does not slowly discharge.

Your issue would be to find an inverter that generates a clean sine wave. This is not usually done with the low end inverters you plug into your car. These usually create a stepped sine wave that can be just as bad for your electronics as a dirty input signal.

If you can find a good inverter, and a solid charger, a good battery, you probably have spent more than if you'd gone out and bought an on-line UPS system.

But it would certainly be more fun making one! :)
 
Thx for the replies. I have a 3750 genny for the not so sensitive stuff.
We rarely lose power here if ever in the cold weather but there's
a first for everything so I think I'll pick up a gen/inverter dedicated
to the pellet stove only.
 
Status
Not open for further replies.