Generators and electronics

[DS]

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

[RBM]

[Eric in North TX]

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.

[David Nebenzahl]

On 1/22/2009 1:48 PM RBM spake thus:

Not stable how? Voltage fluctuations? Frequency fluctuations? Noise? Spikes?

[Eric in North TX]

Yes

[RBM]

[Van Chocstraw]

Power plants use generators.

[Eric in North TX]

[ransley]

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.

[Nate Nagel]

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:

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

[RBM]

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

[ds549]

the honda generator sight reccomends inverter generators for sensitive electronics , i guess the ups mentioned is same thing,different way..

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[Tony Hwang]

Hi, What brand is yoyr gen set? Good ones cost more fora reason.

[ransley]

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.

[Duff]

I vote for the UPS.

I have 3 of them running right now and wouldn't hesitate to run them with my generator.

[EXT]

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.

[Ralph Mowery]

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.

[Bill]

Here is what the electricity looks like from some inverters and generators (not good!)...

[David Nebenzahl]

On 1/23/2009 8:18 AM Bill spake thus:

Now we're getting somewhere; some real-world data to look at.

The waveforms for the Honda generator (EU2000i) actually look better than the power-company's juice. On the other hand, the cheap generators look like hell.

Inverters seem to rule the roost here.

[Van Chocstraw]

I'd want to see the output of ALL cheap generators, not just the worse one and assume they are all like that. Don't fool yourself.