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Total Harmonic Distortion of Portable Generators


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  #41  
Old 02-10-2018, 06:04:58 PM
Graycenphil Graycenphil is offline
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Default Re: Total Harmonic Distortion of Portable Generators

I am not the expert on this, but it sounds like you need really good, clean power for your furnace, and I donít think the EM6500 delivers that. I donít see how you can take the chance of ruining the electronics - hefty repair bill and no heat.

I donít think 550 watts will be a problem, as long as you are slighlty cautious.

They EUs do hold their value pretty well. That tells you what people think of them.
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  #42  
Old 02-10-2018, 06:52:39 PM
Steve Dawkins Steve Dawkins is offline
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Default Re: Total Harmonic Distortion of Portable Generators

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Originally Posted by GeneratorNewb View Post
Maybe I'll just wait until they come down in price.
In all due respect, you can anticipate a very long wait. Hondas usually don't come down in price until they are in the "used" market.
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  #43  
Old 02-10-2018, 06:56:54 PM
DMeed DMeed is offline
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Default Re: Total Harmonic Distortion of Portable Generators

If that furnace is that sensitive to the electrical power - I would be talking to as many owners as I could find and figuring out if the furnace controls will die even on regular utility power - it isn't going to be perfect all the time either. A nearby lightning strike or a welding shop down the street could cause line spikes. Do those furnaces last 15-20 years in people's houses or are they replacing controller boards every few years?
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  #44  
Old 02-10-2018, 07:06:47 PM
GeneratorNewb GeneratorNewb is offline
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Default Re: Total Harmonic Distortion of Portable Generators

Honestly, it's not as much about causing damage as it is about just operating. My HVAC contractor told me that most of these furnaces with ECM motors (variable speed furnaces) need to be damn close to 60hz for the flame rectification. Otherwise it will not ignite and sometimes cause damage. It is a line-sensitive appliance similar to an alarm clock I guess.
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  #45  
Old 02-10-2018, 08:14:28 PM
Rich Mc Rich Mc is offline
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Default Re: Total Harmonic Distortion of Portable Generators

Check out the specs of military MEP-002A 1800RPM 5KW @0.8 pf diesel 79db@25 feet. It is a very robust genset with good stability, recovery, THD and in your budget range. I think that these units can be over powered by 25% for 2 hours without adverse effects.
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  #46  
Old 02-10-2018, 08:18:31 PM
GeneratorNewb GeneratorNewb is offline
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Default Re: Total Harmonic Distortion of Portable Generators

That thing looks like a beast! Unfortunately I need something a little more compact to store in my garage and wheel out as needed. I appreciate the recommendation!
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  #47  
Old 02-10-2018, 08:19:46 PM
Rich Mc Rich Mc is offline
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Default Re: Total Harmonic Distortion of Portable Generators

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Originally Posted by Rich Mc View Post
Check out the specs of military MEP-002A 1800RPM 5KW @0.8 pf diesel 79db@25 feet. It is a very robust genset with good stability, recovery, THD and in your budget range. I think that these units can be over powered by 25% for 2 hours without adverse effects.
Dedicate a small inverter for the furnace only.
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  #48  
Old 02-10-2018, 10:43:11 PM
Power Power is offline
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Default Re: Total Harmonic Distortion of Portable Generators

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Originally Posted by GeneratorNewb View Post
Honestly, it's not as much about causing damage as it is about just operating. My HVAC contractor told me that most of these furnaces with ECM motors (variable speed furnaces) need to be damn close to 60hz for the flame rectification. Otherwise it will not ignite and sometimes cause damage. It is a line-sensitive appliance similar to an alarm clock I guess.
As previously indicated, I have had a bit of experience with those systems. Actually, lot more than maintaining HZ close to 60. As previously discussed, need proper ground plane and building ground system, no excessive voltage spikes or sags. Generator needs an isolated ground and 4 wire hookup, not 3 wire with common neutral/ ground.

I would be looking at something else for heat. Your contractor has clearly warned you that particular heating system will not play nice with a home generator. That warning means unlikely any warranty for damage caused by using other than utility supply.

If you insist on that particular unit, contact the manufacturer and ask what they suggest. Also find out about critical spare parts availability, and how quickly parts will be available in an emergency, like a storm. Does a local supply house stock parts? Suspect you will get a big surprise.
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  #49  
Old 02-11-2018, 01:25:32 AM
GeneratorNewb GeneratorNewb is offline
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Default Re: Total Harmonic Distortion of Portable Generators

Understood, I would be using the 4 wire connection into my panel. How would you feel about using a Honda inverter generator though? I know it has a floating neutral so I'm not totally sure how that would impact flame rectification etc.

I know the rpms vary with load omninvwe generators and they typically produce power that is as clean or cleaner than utility power. Thanks so much!

Sorry for the mistyped words. "I know the rpms vary with load on inverter generators."

I should also note that the panel is connected to a grounding rod right on the other side of the foundation wall and that the 4 wire generator hookup is connected to the panel via a double breaker and interlock kit.

Also, assuming I used another source of heat in a power outage such as a large, gas fireplace insert, are there any other devices I should worry about from a thd /frequency perspective?

I would put router, modem, and phone charger on a double conversion ups. I've read that non-sensitive electronics such as well pumps, window ac, etc can run hotter than usual.

If I'm gonna shell out $4k I'd much rather do it on something that will get a lot of use like a fireplace insert rather than a generator that will be used once in a blue.
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  #50  
Old 02-11-2018, 02:36:31 AM
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Default Re: Total Harmonic Distortion of Portable Generators

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Originally Posted by GeneratorNewb View Post
Understood, I would be using the 4 wire connection into my panel. How would you feel about using a Honda inverter generator though? I know it has a floating neutral so I'm not totally sure how that would impact flame rectification etc. That is what you want- only place neutral and ground meet is in main panel. Flame rectification systems do not like voltage on ground system, that is why neutral and ground paths must be separate. Ground rod does not mean much for this. Ground rods come into play at high voltages, like spikes caused by nearby lightning strikes. 2-8 foot rods spaced out have been required since 1990's.For household voltages, the best ground is the metal waterline from the city water system, which you do not have.

I know the rpms vary with load omninvwe generators and they typically produce power that is as clean or cleaner than utility power. Ha, no way. Thanks so much!

Sorry for the mistyped words. "I know the rpms vary with load on inverter generators."

I should also note that the panel is connected to a grounding rod right on the other side of the foundation wall and that the 4 wire generator hookup is connected to the panel via a double breaker and interlock kit.

Also, assuming I used another source of heat in a power outage such as a large, gas fireplace insert, are there an other devices I should worry about from a thd /frequency perspective? Suggest a good whole house surge protector in main panel

I would put router, modem, and phone charger on a double conversion ups. Should not be necessary.l. I've read that non-sensitive electronics such as well pumps, window ac, etc can run hotter than usual. If you are really worried, THD can be reduced with traps or inductors. Properly installed, even an idling electric motor or transformer will absorb THD.

If I'm gonna shell out $4k I'd much rather do it on something that will get a lot of use like a fireplace insert rather than a generator that will be used once in a blue.
Think about my suggestions in post 48. Even if you never use generator, you want to know availability of repair parts for life of unit.
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  #51  
Old 02-11-2018, 03:12:44 AM
GeneratorNewb GeneratorNewb is offline
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Default Re: Total Harmonic Distortion of Portable Generators

I do currently have a whole house surge protector installed. Do thd /frequency variations have an adverse effect on motors like well pump?
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  #52  
Old 02-11-2018, 11:29:02 AM
Seafarer12 Seafarer12 is offline
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Default Re: Total Harmonic Distortion of Portable Generators

Has anyone mentioned a power conditioner for the sensitive electronics if your worried about them. Most small electronics have a power supply and run on dc.
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  #53  
Old 02-11-2018, 05:26:46 PM
GeneratorNewb GeneratorNewb is offline
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Default Re: Total Harmonic Distortion of Portable Generators

No but it doesn't seem like a cost effective solution if I want the entire 30 amp output to be conditioned. I saw some insanely high prices. I guess at this point I'm between using the generator I have and buying an additional Honda eu2000i. That would be solely for running the furnace. Or just springing for the Eu7000is. Does frequency control /thd have a material impact on motors such as well pump, garage door openers, etc?
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  #54  
Old 02-11-2018, 06:00:47 PM
Graycenphil Graycenphil is offline
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Default Re: Total Harmonic Distortion of Portable Generators

It seems that most household equipment runs fine on any generator. Most folks get by fine with mediocre generators. The biggest problem in a power outage is usually that the generator just quits, or wonít start in the first place. That said, high tech furnaces seem to be one of the exceptions. And in general, cleaner power is always better.

Just looking around, I saw this one that looks like a basically new EU6500 (if you trust the seller) for asking price of $2,800. Maybe heís flexible, or you can just keep your eyes open till something appears for the right price.

https://longisland.craigslist.org/gr...475483908.html
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  #55  
Old 02-11-2018, 06:15:47 PM
GeneratorNewb GeneratorNewb is offline
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Default Re: Total Harmonic Distortion of Portable Generators

That's actually a fantastic find. I'll see what he's willing to take. For around that price I'd much rather go for the Eu7000is as the fuel injection seems like a real game changer.
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  #56  
Old 02-11-2018, 06:17:32 PM
Graycenphil Graycenphil is offline
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Default Re: Total Harmonic Distortion of Portable Generators

The more I think about this, the more I find it annoying. Why would you make a product like these high tech furnaces that wonít run on a generator??!! Is this as cynical as them trying to make money on repairs, or is there some technical reason why it has to be this way? I kind of doubt the latter - if my computer, and all the other high tech stuff around the house works on dirty power, why canít the furnace?

Especially because heat is one of the things everybody buying a generator is going to want to be able to run. many folks buy a generator just for that reason - so the house wonít freeze when the power goes out in the winter.
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  #57  
Old 02-11-2018, 06:57:08 PM
GeneratorNewb GeneratorNewb is offline
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Default Re: Total Harmonic Distortion of Portable Generators

I couldn't agree more. $4k is a lot to spend on a generator especially when considering for a little under 7k I can get an automatic standby unit that will run most of the house.

I can get the 2kwh Honda unit to run the furnace but it seems pretty impractical to be switching between generators to run heat and other appliances. Especially if it's cold out. I think a large inverter or a standby are the only real choices.

I think I'm gonna have to bite the bullet and spring for thr eu7000is. The only other option is to buy a large gas fireplace insert which would get used both during the winter and during a power outage. The problem is our home is 3,300 sqft so it might not be enough. Although we do have another gas fireplace on the other side of the home.
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  #58  
Old 02-11-2018, 10:11:21 PM
I like oldstuff I like oldstuff is online now
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Default Re: Total Harmonic Distortion of Portable Generators

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Originally Posted by Graycenphil View Post
The more I think about this, the more I find it annoying. Why would you make a product like these high tech furnaces that wonít run on a generator?
We have to remember that most devices are designed and tested on nice clean utility power. Sitting in an engineering room or the test floor it's likely nobody considered testing on a dirty sine wave input as the real world might encounter. Much less whip it with floating ground, no ground, earthed neutral etc as will be encountered with gensets.
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  #59  
Old 02-11-2018, 10:28:29 PM
GeneratorNewb GeneratorNewb is offline
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Default Re: Total Harmonic Distortion of Portable Generators

Very true, as I stated before, I read some posts of electricians stating that frewuen deviation and high thd can cause well pumps to overheat. Being that the Hondas use a pure sine wave, I'm thinking the Eu7000is will be ideal. Now I just have to talk myself into pulling the trigger. I guess buy once cry once.

In my development the power lines are underground so we are really only susceptible where the lines originate outside of the development. We lost power once for 6 hrs in the last 4 years but with a baby at home I get a little paranoid. Only other option is sticking with thr wh7500e and only using a space heater in a smaller room, some lights, and well pump.

For the summer I have a window ac I can throw in a smaller room as well (not sure how much that would be affected by the higher thd numbers).
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  #60  
Old 02-11-2018, 10:51:26 PM
Graycenphil Graycenphil is offline
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Default Re: Total Harmonic Distortion of Portable Generators

There is a general rule that the likelihood of your losing power is dramatically reduced by getting a generator. Kind of like insurance; you may never need it. But if you do need it, it’s really nice to have.

Quote:
Originally Posted by I like oldstuff View Post
We have to remember that most devices are designed and tested on nice clean utility power. Sitting in an engineering room or the test floor it's likely nobody considered testing on a dirty sine wave input as the real world might encounter. Much less whip it with floating ground, no ground, earthed neutral etc as will be encountered with gensets.
I’m sure you’re right, but really, couldn’t somone figure out this might be an issue. I’m not an electrical engineer, but I do know about boilers and furnaces, and it seems to me it shouldn’t be too hard to design hadier controls.
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