Clean generator power

Can someone explain to me the dangers of powering household appliances with a cheap AC generator/ I understand that the cheapest of generators create a square wave DC pulse rather than a smooth sine wave and voltage may not be steady under a load but why is this a problem? What am I risking? I am using a brushless Brigggs and Stratton generator with10k continuous watts.
 
This is the generator
 
http://www4.briggsandstratton.com/om/pdfs/9801_8efs1w.pdf
 
Mike.

There are 3 factors (at least) that contribute to the quality of a generator's output:  voltage, frequency and distortion.
 
Voltage regulation is important because as loads are added or dropped, the voltage can deviate from 120V/240V, sometimes significantly.  Generators often have trouble maintaining proper output under light loads, and also when nearing their maximum load.  Automatic Voltage Regulation (AVR) helps, but doesn't fix everything.  Obviously, too high a voltage can damage components in electronic devices.
 
The output frequency should be 60Hz, but can vary as the load changes and the engine speeds up or slows down (and also when fuel gets low).
 
Generators often produce fairly noisy output sine waves, which result in high total harmonic distortion (THD).   A nice clean sine wave has low THD.  For electronics with microprocessors and such, you'd really like THD to be below 3%.
 
Many electronic power supplies contain magnetic components (e.g. transformers and inductors) which are sensitive to changes in frequency and waveform distortion.  When the sine wave input isn't as clean as it should be, the circuits may not function as they are supposed to, and cause damage.
 
Some of these specs are hard to find on many generators.
 
Generators that have inverters on their output usually provide good clean power.  But they cost more due to the additional hardware.
 
 
Some reading material:
 
http://powerupgenerator.com/total-harmonic-distortion-portable-generators/
 
http://stonehavenlife.com/can-portable-generators-damage-home-appliances/

I found a general statement from B&S in response to a customer question on Home Depot's web site that says THD for all B&S generators is 3-6%. 
 
So, it's in the pretty good range, but not so awful that I'd be extremely worried.   Might be worth a call to B&S to see if they can give you a number for your generator.
 
[Edit]
 
I found some additional info on the B&S web site, some of which is conflicting...
 
"The True Harmonic Distortion is 3-6%"
 
"We do not rate the THD of our portables."
 
"The THD on the unit is 3 to 6%. To run sensitive electronics on the unit we recommend using an inline cleaner, this will make sure that the power getting to the electronics is clean."

I will give Briggs a call and see what they say about the THD.
 
My personal experience has been good so far, I ran a 6500 watt Coleman camper generator biult in the 1970's on this house several times in outages through the years and everything ran fine. That was a brush type generator and this new Briggs that replaced it is brushless which may make a big difference.
 
I have learned that the frequency is regulated by the engine rpm and that 3600 rpm should give me 60hz. Then the voltage can be regulated by changing the value of a capacitor in the machine. I do have a meter that can measure HZ and capacitance so I'll see what I have when I get to work on it.

Would the battery in a decent power backup unit like APC makes for computers isolate stereo equipment and the like from unstable power from a portable generator?

Much of this link is over my head but it is interesting
 
http://www.dslreports.com/forum/r27117217-Dirty-Power-Cleanup

mikefamig said:

Would the battery in a decent power backup unit like APC makes for computers isolate stereo equipment and the like from unstable power from a portable generator?

Click to expand...

 
With most low-cost UPS designs, the UPS operates in pass-through mode as long as there is 120VAC at the input.  So if you put one of these on your generator output, it will not do much to clean up the power.  Many UPS's these days provide some sort of voltage regulation, but that is just "adjusting" the voltage output to keep it near 120V, and it doesn't clean up other things that may be wrong, like frequency or distortion.
 
When the AC power goes out, the UPS may or may not provide a good sine wave output.  Some use square waves (or stepped square waves) to simulate a sine wave.  More expensive UPS's produce a pretty good sine wave.  These often mention "pure" or "true" sine wave output in their descriptions.  But you get that only when running on the battery!  Here's an APC model that has this.
 
There are UPS's that do provide clean output all the time.  These are double conversion models (also called "online" UPS's). They convert the incoming AC to DC, then use an inverter to convert the DC back to AC.  The connected equipment always gets the clean output of the inverter.   The downside is that these are expensive - you're talking about $500 for a small one, like this Tripp-Lite.

Maybe it's just me, but thinking... Wouldn't it be nice if appliance/electronic manufactures built in line conditioners, so that this sort of thing didn't matter? ... Or at least mattered less. 
 
But then those who never use a generator and had clean power - would complain about the increased cost. 
 
I've lived in hurricane country for almost 30 years and have never owned a generator - certainly on the list of things I probably should have though. I've borrowed a friends ONCE... when I was working on a new construction house and my battery powered drill wasn't enough to drill 1" holes through the double 2x4 top plates. My corded hammer drill did the trick  

drvnbysound said:

Maybe it's just me, but thinking... Wouldn't it be nice if appliance/electronic manufactures built in line conditioners, so that this sort of thing didn't matter? ... Or at least mattered less. 
 
But then those who never use a generator and had clean power - would complain about the increased cost.

Click to expand...

 
Yes, I agree. The trouble is that manufacturers will go to extremes to reduce cost, and so they eliminate anything that isn't absolutely necessary.
 
A friend of mine designs power supplies for a living.  There are lots of good power supply designs out there, often put forth by the companies that produce the voltage regulator and controller components.  My friend says what the off-shore suppliers do is they remove the surrounding components (e.g. capacitors, diodes, resistors) one by one until it stops working.  Then they add the last part back in and declare that to be the shippable product - a barely working design.

I just spent a couple of hours wrestling with an old oscilloscope that I bought many years ago. It worked when I put it away but when I powered it up earlier today the display was blank. I opened the hood on it and it appears that there is no high voltage to the CRT. It looked like it could be that the power switch is not energizing the rather large power transformer or maybe the transformer went bad. I was hoping to find a bad fuse or something simple and I got tired so I gave up for now.
 
It would have been fun to look at the power from the generator but that's not happening now. I am on day 7 of a nasty flu that is finally subsiding but I've had enough for one day. I've heard that it's a a bad year for flu nationwide.
 
Mike.

RAL said:

Yes, I agree. The trouble is that manufacturers will go to extremes to reduce cost, and so they eliminate anything that isn't absolutely necessary.
 
A friend of mine designs power supplies for a living.  There are lots of good power supply designs out there, often put forth by the companies that produce the voltage regulator and controller components.  My friend says what the off-shore suppliers do is they remove the surrounding components (e.g. capacitors, diodes, resistors) one by one until it stops working.  Then they add the last part back in and declare that to be the shippable product - a barely working design.

Click to expand...

Ugh. I'm starting to dislike Chome as a browser now. I had a response typed up and stepped away for a bit... was doing some other web-based work on other tabs. When I came back, Chrome auto-refreshed this page which lost everything I had previously typed. So I'll start over... 
 
Anyhow, that's the same experience I'm aware of as well. 
 
My first interview after graduating with my BS degree was with a HVAC manufacturing company. They told me if I hired on and took the advertised position, my first task would be to reduce the manufacturing cost of one of their models by 50% within a year. This would have been done either via what you described above, via cheaper distributors, or via cheaper materials. I wasn't too excited about the work and never took the follow-up interview. 
 
Having said that, I typically research every piece of equipment in some capacity prior to purchase. Many times it frustrates family because they tell me it makes buying things for me (i.e. gifting) very difficult for them - sorry I don't mind paying a little bit (sometimes considerably more) for a better built product. Many times I'll hear the, "but it's the same thing", when in-fact I've done the research and found the more expensive model is actually manufactured with superior components, and is simply better built and will be more reliable and likely last longer. I've many times borrowed a quote from a co-worker (at least the first place I heard it) which is: Buy it nice, or buy it twice! 

Related, What has the experience been with running a UPS when the generator is On-line?  Has anyone found a good UPS that will go off battery and condition the generator output? (dual conversion)
I have spoken to quite a few UPS companies and am really surprised that this seems to be something that most haven't gotten inquiry about.
The most common answer is "the UPS can be configured to accept a "dirtier than usual" signal".  My experience is they still won't go off battery when the generator kicks in.
 
Most common generator I have run into is 10-15KV Generac propane or natural gas.
 
The problem is the sensitive electronics (security system / home controller) will shut down once the UPS battery is dead - even when the generator is providing plenty of power.

When we say clean power, to me that means voltage and frequency.
 
I took a different approach, and just power my critical loads from battery in the case of an outage. Think Tesla's PowerWall, or in my case, an SMA Sunny Island that powers a critical loads panel either from the grid or a battery (and I have 4 8D AGM batteries). You could always have a generator that separately powers loads that aren't as freq/v sensitive (eg: motors... furnace fan, fridge, freezer, etc). Many generators also are paired to batteries to provide surge loads... so that a 10kw generator can start a large A/C (where surge load for the compressor motor and furnace fans -- think 2x typical running loads) might be too high for a specific generator, but the running loads are not)
 
Or, a different implementation would be to use that inverter in series with your generator. Depending on the generator's specific type of "dirtiness", the Sunny Island can be configured to condition generator output,auto-start/stop the generator, and manage generator load (eg: don't overload): White paper
 
A Sunny Island costs around $4000-5000 depending on how much wattage you want to protect (4.5kw to 6kw)
 
 
 

Related, What has the experience been with running a UPS when the generator is On-line?  Has anyone found a good UPS that will go off battery and condition the generator output? (dual conversion)
I have spoken to quite a few UPS companies and am really surprised that this seems to be something that most haven't gotten inquiry about.
The most common answer is "the UPS can be configured to accept a "dirtier than usual" signal".  My experience is they still won't go off battery when the generator kicks in.
 
Most common generator I have run into is 10-15KV Generac propane or natural gas.
 
The problem is the sensitive electronics (security system / home controller) will shut down once the UPS battery is dead - even when the generator is providing plenty of power.

politics123 said:

When we say clean power, to me that means voltage and frequency.
 
I took a different approach, and just power my critical loads from battery in the case of an outage. Think Tesla's PowerWall, or in my case, an SMA Sunny Island that powers a critical loads panel either from the grid or a battery (and I have 4 8D AGM batteries). You could always have a generator that separately powers loads that aren't as freq/v sensitive (eg: motors... furnace fan, fridge, freezer, etc). Many generators also are paired to batteries to provide surge loads... so that a 10kw generator can start a large A/C (where surge load for the compressor motor and furnace fans -- think 2x typical running loads) might be too high for a specific generator, but the running loads are not)

Click to expand...

 
The Tesla battery is no substitute for a generator in a power outage. It's a battery that is ideally suited to a solar cell system. It only stores enough power to run a home for a few hours at night and then recharge when the sun comes up. It requires an inverter in the installation and the total starting cost is about $6000.00. You also need to wire your house so that all of your sensitive equipment is on the power wall circuit. I can see where you could utilize the power wall in an outage if you already have a solar system and the batteries installed but not as an accessory aid to an emergency generator.
 
 

politics123 said:

Or, a different implementation would be to use that inverter in series with your generator. Depending on the generator's specific type of "dirtiness", the Sunny Island can be configured to condition generator output,auto-start/stop the generator, and manage generator load (eg: don't overload): White paper
 
A Sunny Island costs around $4000-5000biepending on how much wattage you want to protect (4.5kw to 6kw)

Click to expand...

 
This is a little more practical as an addition to a generator but the price again is a deal breaker. I have a 10k generator and it would be cheaper to replace a tv now and then than to buy protection at such a price.
 
I think that it would be much more practical for me to stay with what I have and risk equipment damage or buy a generator with a built-in inverter.
 
Mike.
 
EDIT
 
It would be difficult for me to isolate the sensitive loads at the load center/switch  because they are all over the house. There is sensitive equipment is on most of the circuits. For me it would make more sense to find a device that is placed at the sensitive equipment. I would think that some line filters would be better than nothing.

For relatively small cost, especially since you can purchase individual UPSs and make individual component-level decisions:

1. Connect sensitive electronics to UPS
2. Automate the 110v outlets that the UPS is plugged into. When there's a power-outage, shut-off the outlets so that the "dirty generator power" never gets to the UPS
3. When grid-power comes back, you turn on the outlet to your UPS and the UPS battery recharges.
4. You can size the UPSs to handle a "normal-duration" outages. The lower the amount of time required, the cheaper the UPS

 
When you have an extended outage:

• you can always turn on the outlet and run from generator (so now the UPS has 110v at the plug and passes through the power to the equipment, at some risk of equipment failure. -- with some supplemental planning, you might be able to reduce this risk by doing that cut-over at times where the generator isn't strained... the dirtiest power comes when the generator is at capacity.
• OR, you can daisy chain your UPS batteries... for example, have a two batteries in parallel... and after an hours of failure, disconnecting one of the batteries ("low capacity") and replacing it with a fully charged battery, and then disconnecting the second "low capacity" battery... charging them both up, rinse/wash/reuse the same process to keep power running for as long as their's an outage.
• OR, you can simply shutdown the equipment, plug it into a different UPS, and turn the unit back on again. (this would be my choice)

-Michael