Risk of Appliance Damage from Portable Generator?

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When a portable generator (non-inverter type) of 5000 to 7500 watts is connected to the house electrical system during a power outage, is there a real risk of damaging appliances such as furnaces (control board), refrigerators, microwave ovens, TVs, etc. ? (Assume the generator has automatic voltage regulation.)

I have been looking at user reviews of Champion and Generac generators (around the $600-$650 price point) and have yet to see a complaint about damage to household appliances, even to computers and routers/modems. But online buyer's guides imply it is a significant risk.

What have your experiences been?
 
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Most electronics aren't that sensitive. With a mechanically governed engine you'll see the voltage and frequency a little high at light load, but it's generally a non-issue. Old clocks may run a little fast.

My gut feeling is that the buyer's guides aren't based in fact. Yes, inverter generators are better with frequency and voltage control, but the wave form isn't necessarily better.

Also, I would rather have a used Honda than a cheap new unit. My Honda EG1400 cost me more than a similar sized Champion was new, but it's Honda quality and has Honda parts support.

I've played with a few different generators at home and only had trouble with an ancient (1940s I believe), brushed, 1000 watt generator. My guess is that the inductance in the generator and the refrigerator (the only load at the time) didn't play well together. My 1200 watt brush-less Honda and the refrigerator get along fine. The ancient (1950s) 5kW Winco was a beast and shook the house, but would run all the lights, the frig and heat water!
 
During the ice storm of 1998 there were a bunch of furnace control boards fried here.

I think people go to bed with 5 gallons in the tank and let the things run out of gas, with the resultant surging and slow drop to zero volts. That can't be good for anything.

Some AVR types kill ignition if they can't keep a good voltage, but IDK if they also have a breaker on the output side when the volts drop below 90-ish. That would be swell to have, since running out of gas with stuff attached must happen daily in the real world.

The nice thing about AVR is it "doubles down" on the engine's governor-- an increase in load means an instant increase in amperage draw to make up for the voltage drop, so it "knows" it has to speed up twice as fast.

I finished off an old fridge with a clunky ancient generator and its sticky governor-- suffered a "brownout" and the compressor sounded bad, smelled hot, and died before I could reach it to unplug it. If your fridge compressor sounds right, things are good.

NB, on my new generator the frig sounds "ever so slightly off" but still works. An unclean waveform makes the spinny stuff want to jump sideways out the motor case. Too much voltage is better for the equipment than not enough.
 
Originally Posted By: eljefino
During the ice storm of 1998 there were a bunch of furnace control boards fried here….


Do you know if portable generators of 18 years ago typically had AVR?
 
I suspect no AVR back then. It was a "new thing" when Chondas were hitting it big.
 
Computers, TV's, and other electronics all convert the 110v to DC to run stuff and they typically have universal power supplies that will work with anything decent and convert it to clean DC.

Resistance heaters like the oven, hot water heater, etc could care less.

As long as the volts are close to 110-120v and 55-65 on the Hz you should be fine.

I've run tons of stuff, including electronics and our washer and dryer (with their electronics) off our Harbor Freight 5500w generator.

Just plug in a volt meter if you are going to run it for long periods of time and don't run it out of gas. Disconnect all loads before powering the generator off and add them a few at a time.

I'll take a Chonda over a Honda any day of the week and twice on Sunday. Honda (in all they do), IMHO is way overrated.
 
The trick is to keep the rpm up so the frequency stays at 60 HZ or above. Transformers and motors work ok on higher line frequencies than those they are designed for
but not lower. Most power supplies and wall warts are switchers these days and don't much care.
I'd like to know what EXACTLY failed on those furnace controls. It wouldn't be hard to connect a gas furnace control board through a computer back up power supply to protect it.
 
Many people avoid using appliances that are not critical. Like washer and dryer. When your on generator you only run the basics. I think other people run too much when on the generator. I would turn on items with motors one at a time. Let each refrig/freezer come to temp one at a time.
 
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Motors need clean 110-120V 60hz sine wave power to function reliably. Make sure your AVR generates sine waves and not square waves. You are very unlikely to have issues with any modern electronics, they are quite tolerant, but desktop computers may freeze from voltage fluctuations.

A higher capacity generator run at a low load is most likely to give you clean output.
 
Most sensitive electronics use DC power supplies. Those power supplies take 50 or 60HZ, 110 to 240V AC power, filter it and reduce the voltage to a electronics friendly level (typically 5v) and convert it to DC for use by the electronics. They fully isolate the electronics from the AC power.

It's unlikely that the slightly unclean power of a portable generator will damage the electronics. It's much more likely that a significant power surge, such as a lightning strike, will damage electronics.
 
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Microwaves are interesting, because the "magnetron" is tuned to a particular frequency and is operated by line voltage/frequency. So, an off-frequency generator, or unclean power will cause the magnetron to misbehave. Often they complain by making strange noises and food won't heat properly.

Don't confuse a magnetron with sensitive electronics though. They are different.
 
I've run my kitchen appliances, lights, furnace and my computer/printer/monitor off my Briggs & Stratton 5500 running Watt generator through a manual transfer switch without any problems. All ran the same as using the utility company power.

Whimsey
 
For the most part, appliances should not be damaged. But there are different types of electric motors, shaded pole, universal, capacitor, and for front loading washing machines DC motors to name a few.

I think the wise advice is to use as few non critical appliances as possible. If you have a well pump it will probably be the largest electric motor you will run with your generator. I turn off my well pump unless the outage appears to be long lived.
 
I can't vouch for the accuracy of this statement, but here it is anyway:

"...In conventional electric gensets, the output is a raw voltage induced in a coil by a rotating magnetic field. Unlike grid-supplied electricity, this voltage is not a pure sine wave and may contain significant level of higher frequency harmonics. While total harmonic distortion (THD) of less than 5-6% is generally considered acceptable, some portable gensets produce THD>15%…………………………….

...In addition to this, cheap portable gensets may not have an automatic voltage regulator (AVR), can't react to rapidly changing loads and will produce power surges or sags. They may even destroy an appliance sensitive to voltage fluctuations, such as a refrigerator's compressor. If you connect your electric load via a UPS power supply, it may not even recognize such a genset as a normal power source and may switch to battery mode. The cleanest power of all sources is produced by sine wave inverters, which are best for sensitive electronics. That is why many genset manufacturers introduced the inverter technology into their product lines…"

http://www.generators.smps.us/inverter-generator.html


I looked at half a dozen spec sheets for 5500W portable generators, but never saw a specification listed for THD.
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Raw voltage? I have trouble taking this guy's writing completely seriously. It could be due to the fact that he's not a native English speaker.

A stator with a rotating magnetic field produces a sine wave. A small generator may not produce a perfect sine wave. Not because of the construction of the generator itself, but because the engine speeds up and slows down with every other revolution on a 4-stroke-cycle single-cylinder generator set.

Inverter generators allow smaller rotating electrical components which save weight. They can also be run at varying speeds which reduces part-load fuel consumption. Inverter generators were not designed specifically to have a cleaner output, but may have a cleaner output. Then again they may not.

You know how grid power is produced? Big revolving electromagnets and large conductors. Only on certain long distance point-to-point transmission lines do you go from AC to DC and back. And that's done to eliminate the losses from inductive effects.

My suggestion is to buy a generator for which you can easily buy replacement parts or treat it as semi-disposable. Regardless of what you buy make sure it works before you need it. A friend bought a Champion and the starter mechanism exploded the first time he tried using it. Which was after hauling it from Oregon to Baja, Mexico.
 
I have a Champion Power equipment 3500w running/4000w surge generator with the AVR. During an ice storm last year I ran my house on the generator for most of a saturday. The power output of the Champion units seems very steady. I ran the furnace, 2 refrigerators, a chest freezer, some lights and an LCD tv. Everything ran the same as it did on utility power.
It even ran my well pump, but I turned everything else off and only ran it a couple times.

I also have a Champion 2000w inverter I use on camping trips in the summer.
Overall, I am very impressed with Champion generators.
I did have to order a couple parts ( due to my abuse/breakage, not defects). You can order parts direct from Champion, they ship quick from their warehouse in California, and the part cost was very reasonable.
 
Originally Posted By: eljefino
During the ice storm of 1998 there were a bunch of furnace control boards fried here.

This may have had more to do with the electronics of that vintage than the wave form coming off of the generators. The control board on my own Carrier system fried around that same time frame on utility power alone. Simple transformers were the norm in power supplies back then, whereas now switching power supplies are nearly universal.

Originally Posted By: cronk
I have a Champion Power equipment 3500w running/4000w surge generator with the AVR. During an ice storm last year I ran my house on the generator for most of a saturday. The power output of the Champion units seems very steady. I ran the furnace, 2 refrigerators, a chest freezer, some lights and an LCD tv. Everything ran the same as it did on utility power.
It even ran my well pump, but I turned everything else off and only ran it a couple times.

Pretty much the same generator and situation here. I've run three refrigerators, including one 70 cord feet away at the neighbor's, a chest freezer, the dishwasher, furnace blower, a gas hot water heater blower, some LED lighting, one desktop computer and one server without incident. One day we made dinner in the crock pot with some of that running. The 1/2 HP garage door opener has also been operated a few times with much of the above running. The misses even had to use her 1300 watt hair drier during one outage. Thus far nothing seems any worse for wear.
 
Originally Posted By: cronk
...Overall, I am very impressed with Champion generators...


I was just about to pull the trigger on a 5500W Champion from Amazon, but they increased the price by $100 overnight.
mad.gif
They must be in high demand right now, because of floods I am guessing.
 
Originally Posted By: SubLGT
Originally Posted By: cronk
...Overall, I am very impressed with Champion generators...


I was just about to pull the trigger on a 5500W Champion from Amazon, but they increased the price by $100 overnight.
mad.gif
They must be in high demand right now, because of floods I am guessing.


do some shopping on ebay. I bought my 2000w inverter through ebay from a company called Supergen Products. They have a pretty good selection of Champion gennies on their ebay store with good prices and free shipping. Sometimes they have factory refurbished units for great deals also.
 
I would say as long as your generator is tuned properly and running well you shouldn't see any problems, inverter or conventional. As already mentioned switching power supplies really helped out with electronics. Most accept anywhere from 90 - 260 volts and frequencies in the range of 47-63 hz.

I have two champions, a 5kw and a 7kw. The 7k was pretty much ready to go out of the box but the 5k was set a little slow. I set both of them at 63 - 63.5 hz zero capacity. Since most people use their gens at 50% capacity this will get you as close to 60 hz as possible.
 
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