Generators and electronics

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We live in the country and the power goes out quite often. So I bought a 5000 watt generator, properly connected, which powers the furnace, the water pump, the freezer anbd refrigerator and several light circuits. I'm told it is not wise to operator sensitivre electronics such as big TV sets and computers on generator power. In fact I'm pretty sure thats hiow I blew a DVD/VHS unit last year. And the digital read out on the refrigerator has lost part of its alphanumerics. My question...what is and is not safe to run?. Will a surge protector ahead of the device in question prevent a problem?. I actually ran a small TV without a problem but not for very long. Would appreciate a reply from some electrical guru. ds
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On 1/22/2009 1:48 PM RBM spake thus:

>

Not stable how? Voltage fluctuations? Frequency fluctuations? Noise? Spikes?
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Yes
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I have said it before and I will say it again. A "generator" is two items, and engine and the electrical generator. Usually a manufacturer may make one part and buy the other to assemble the unit, sometimes they buy both. It is usually easy to identify the make, model and type of engine to check out its quality and approximate usefulness. Many times it is impossible to identify the make, model and quality of the electrical alternator used to generate the electricity. It is the quality of this part that determines the quality of the electricity made. Many create electricity with bad sine waves, with voltage spikes, brush noises and other problems that can destroy some electronics. Quality generators will have both good engines and good generators, sometimes the generators will be a branded model such as the Stamford-Newage. Cheap generators do not have any quality parts and do not usually produce quality electricity.
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Looking at the wiring diagram of my 5 KW generator it looks like the brushes are not for the 120/240 power but for the megnetic field generation. That is the AC output of the generator does not go through any brushes. Would this make the bad brush noise ?
Lots of electronic devices have switching supplies in them and the sine wave internally generated is not that great either. It is then converted to DC to run the internal electronics. I can see the voltage fluctuations causing problems.
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Unless you've found some real old piece of crap, generators put out power to the same voltgae/freq specs the grid uses. Other things about them can bother electronic equipment, but not those fluctuations unless the genset if being overloaded.
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The problem is more a matter unstable & unfiltered than surges I don't think a surge protector would help. A really good UPS might though. We lived on our generator for 2 weeks following a storm a few years ago, I finally freaked after a week & booted a computer to make sure the internet hadn't forgotten me. I was probably lucky, it didn't seem to do any harm, but it was up less than an hour.
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Good reason why so many use Honda generators; not some discount generator attached to a Briggs & Stratton engine.
Surge protectors are for single events that occur typically once every seven years. Repeated 'surges' means protector failure and no appliance protection.
Computer grade UPSes output electricity so dirty (and constantly) that manufacturers quietly recommend no surge protectors on a UPS output. Just another example of why the surge protector question is an obvious "No solution".
What does a UPS do? It typically connects AC electric directly to appliances when not in battery backup mode. Instead, many assume a UPS magically 'cleans' electricity. Well the 'cleanest' electricity comes directly from AC mains - when UPS is not in battery backup mode. 'Dirtiest' electricity (and why a surge protector should not be connected) occurs when UPS battery provides power.
Solution starts and ends with that generator.
Read numbers provided with a laptop. What voltages must a laptop work at? Any voltage from 90 to 260 volts. What happens when a 120 volt generator outputs 150 volts? If may harm a refrigerator or DVD/ VCR. But it must not harm the laptop. Others feared damage because they did not first read the numbers. Laptop would be more robust than the refrigerator.
What does each appliance manufacture list for voltage variation? Always first get numbers. Just more reasons why some generators (ie Honda) cost a little more money (as well as operate so much longer on same fuel when loads are constantly changing).
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That's bass ackwards, but in my case I've run my computer on the genset via my UPS with no problem. I know it's not advised, however, to run them directly. I've looked at the output of mine with a scope and it's actually a very good sinusoidal output with no spikes/surges on it. House-born surges however tended to be higher than normal, probably because of the last of the grid xfmr and split phase connection. Not sure I'd do it without a UPS though without knowing a lot more about the output specs than they normally give.
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DS wrote:

Power plants use generators.
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wrote:

& the trash man had a horse, but it would not be confused with Man o'War
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60hz 120v is at 3600 rpm, some cheap units have poor govenors and even better small units move alot in voltage from low to high load. You need to monitor and know your unit and how to adjust engine speed and monitor voltage. It is safe if load and speed is constant.
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wrote:

60hz 120v is at 3600 rpm, some cheap units have poor govenors and even better small units move alot in voltage from low to high load. You need to monitor and know your unit and how to adjust engine speed and monitor voltage. It is safe if load and speed is constant.
There in lies the problem. With well pumps, refrigerators, burner motors, they ain't nothing constant
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Bigger units with what ever voltage stabilisation they advertise may only swing 4-5v, or dont start the things with big surge and draw when watching tv. Running a gen is expensive anyway, just to get by.
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On Fri, 23 Jan 2009 04:46:52 -0800 (PST), ransley

There you go again ransley. Tossing out numbers from your ass. 4 or 5v? You get that out of the air after you smoked a joint with your sister in your trailer? Im going to go get my shovel because the shit you are slinging is getting deep in here. Bubba
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Hey Bubba. Mr Moron, Mr dont know nada, I have 2 gens I have tested many Mr Moron, I know gens and how they perform.
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On Sat, 24 Jan 2009 05:19:19 -0800 (PST), ransley

....always talking but never anything to back it up. Make up some more shit ransley. By the way, your breath smells like dick. Bubba
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DS wrote:

If you have a computer that you want to run during a power outage, and it is considered "mission critical" run it through a "true online" style UPS, something like these:
http://www.tripplite.com/EN/products/product-series.cfm?txtSeriesIDf1&EID 820
NOT cheap, but if it absolutely positively must be protected, it's what you need. Basically the line voltage charges the batteries, and the load is connected to the inverter *all the time* so the power delivered to your computer is dependent on the quality of the inverter, not your generator.
This certainly isn't a practical solution for every piece of electronics in your house, however. Not sure how much a typical "surge suppressor" will help when dirty power from a generator is the issue.
nate
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