Electricty and "Clean" Power

[BSR6]

Can anyone chime in on the best way to ensure clean power for sensitive electronics when running on a generator without spending a fortune on a Honda that produces clean power to begin with? Even if I did spend the coin on a premium grade generator, I'm being told the shape of the waves can still be off and therefore the power isn’t truly "clean".

I’ve found such options as ac line conditioners, running battery back-ups as a filter etc. The problem is the “solutions” I’ve come across vary greatly in terms of both complexity and cost so I'm starting to get confused as to what is really effective/necessary.

Ideally I'm hoping someone can give me some explanation as to how it all works. It's proving to be one of those topics you can't just research as it requires some strong fundamental knowledge (which I don't have) to fully understand.

[jasnmar]

As I'm sure you've figured out, lotsa variables here.

How clean do you need it to be? What kind of equipment are we talking about?

Most modern power supplies are very "unfriendly" to generators (of all kinds, not just small ones) as they "sample" specific parts of the sin wave and cause distortion. This is a problem in many commercial spaces with high computer loads even when operating on utility power. It can cause excess current flow, overheating neutral conductors, and random power problems with equipment.

How much of the generator load is going to be electronic equipment vs "traditional" (resistive or inductive) loads?

What size loads are we talking here? 2kw, 200kw, 2Mw?

There are things like power conditioners available, and things like rotary UPS systems that can help, but it's not terribly straight forward (and I've not really been involved in this side of stuff for like 10 years).

[BSR6]

OK so that explains my confusion...Apparently it's not a simple topic.

Mainly, I'm concerned with the TV and associated equipment (stereo receiver, DVD Player, Cable Box, etc.), Furnace and associated equipment (such as the blower motor, the computer module thingy that controls dampers, etc) and kitchen appliances such as refrigerators which I'm being told are sensitive as well.

Other than that you have lights, well pump, etc which from what I understand will not be effected by the "dirty" power.

[xsiliconkid]

OK so that explains my confusion...Apparently it's not a simple topic.

Mainly, I'm concerned with the TV and associated equipment (stereo receiver, DVD Player, Cable Box, etc.), Furnace and associated equipment (such as the blower motor, the computer module thingy that controls dampers, etc) and kitchen appliances such as refrigerators which I'm being told are sensitive as well.

Other than that you have lights, well pump, etc which from what I understand will not be effected by the "dirty" power.

All that stuff is going to be just fine one a normal rotating mass generator (keep away from the all cheap electronic ones). If you are worried you can add a conditioning power strip on the electronic stuff.
With sensitive electronic equipment, I use one of these (pure sine wave invertor) powered off a battery which has a battery charger connected to the battery.
Xantrex PROsine 1000W, 12V Inverter with GFCI Outlets

[TheIglu]

I have a cheap(ish) Briggs and Stratton generator from Home Depot.

Ran all those things you listed and more for days during the big ice storm. No issues.

[Stromper]

I am with stupid

I winced when the family started up HD tvs and computers but they were all fine with cheapo 4500 whole house

I DO have redundant spike protection though but that is all

[RandyO]

I have a cheap(ish) Briggs and Stratton generator from Home Depot.

Ran all those things you listed and more for days during the big ice storm. No issues.

same here, I have a cheap ass Coleman generator with a Tecumseh engine I bought from Northern Tool over 20 years ago

my computers are all on UPS as power conditioners, and ALL my electronic equipment (TV, stereo, even digital controlled coffee pot, and low voltage power supplies) are protected with simple metal oxide varistor surge protectors

never had a problem like Clay, running for days on generator

I have had damaging power surges from the power company, I learned the hard way and that is reason I have surge protectors on every thing

I lost a photocopier, digital controlled coffee pot, 4 telephones and a dozen or so surge protectors that did their job that luckily I had on my more expensive equipment

[Garandman]

My paranoid friends put their electronics on the other side of a UPS.

YMMV. A laptop, for instance, usually has a power supply that will accept a wide range of voltages and cycles so they do fine.

[boosten lebaron]

A pure sine wave inverter is the way to go or use a line conditioner. Some ups systems stabilize the wave length as well.
I agree that you will probably be fine with all your electronics but I still wouldn't take the chance. I usually don't even run my TV or computers when I'm on the generator. I use my solar panels for those if I really need them. That system is one a pure sine wave inverter.

[xsiliconkid]

A pure sine wave inverter is the way to go or use a line conditioner. Some ups systems stabilize the wave length as well.
I agree that you will probably be fine with all your electronics but I still wouldn't take the chance. I usually don't even run my TV or computers when I'm on the generator. I use my solar panels for those if I really need them. That system is one a pure sine wave inverter.

Have you ever probed the invertor sine wave output under load with an oscilloscope?

[audiojeff]

What you are looking for is called a full online UPS or double conversion UPS, and you probably don't need one. Just in case, here is a white paper that explains "how it works". lit.powerware.com/ll_download_bylitcode.asp?doc_id=12403 Its from a manufacturer of such devices, fwiw.

The only home electronic systems I use that are especially picky about generator power are whole home dimming systems, and the best of those now compensate for lower quality power. That said we do have some guidelines.

1. Over-size the generator, at startup, the inrush current of many loads can reach 8-10 times the steady state current. If using the steady usage specs on a generator, we suggest that a factor of 3 should be used.

2. Use a generator equipped with a voltage regulator for non-linear loads.

3. Configure the generator to get the lowest possible source impedance, which will also mean less distortion of the output.

4. Include some static loads on the generator.

5. Generator should have a full sine wave output.

6. Generator should have a < 10% THD rating.

[Stromper]

Similar topic I put on a whole house surge protector right on the main panel cost like $100

[Garandman]

audiojeff, maybe you can answer a peripherally-related question for me.

Our NH place has a 14KW genset that comes online automatically. If we had all the electric baseboards and some appliances running, we would exceed the 14KW. What would happen?

[ZX-12R]

audiojeff, maybe you can answer a peripherally-related question for me.

Our NH place has a 14KW genset that comes online automatically. If we had all the electric baseboards and some appliances running, we would exceed the 14KW. What would happen?

It depends on the generator and its associated electronics. For non-inverter based generators, you could have a brownout, reduced frequency, tripped breakers, overheated generator windings, or any combination of those. If it's inverter based, the electronics may have built in protections that just shut off the output until the fault is cleared. The symptoms for the non-inverter apply too.

[Garandman]

Believe this is what we have: has an automatic transfer switch.

KOHLER Generators | 14RESAL with Automatic Transfer Switch | Generators | Products | Home Generators

[audiojeff]

audiojeff, maybe you can answer a peripherally-related question for me.

Our NH place has a 14KW genset that comes online automatically. If we had all the electric baseboards and some appliances running, we would exceed the 14KW. What would happen?

The generator would probably be fine, your unit has two different types of protection. It monitors output, and has fault mode protection, and it is likely connected to conventional circuit breaker protection. The gear connected to it however might not fare so well. Depending on how sensitive the output monitoring, as the load goes up the frequency of the output can drift (not great for motors and compressors) and the voltage will drop. Many types of electronics will try and make up for this voltage drop by consuming more current, sometimes more current than they are designed for. That's when the bad stuff happens.

The damage will depend on how robust the attached devices are. BTW, most surge suppression equipment is useless in protecting for this type of event. Some gear has "under-voltage" protection, but such devices are few and far between.

[Stromper]

Every generator I have ever seen has circuit breakers on the output

If you draw too much they trip and current is interrupted

[audiojeff]

The breakers are rated to prevent the circuit from drawing more power than the wiring can handle. They are not designed to protect equipment.

[Kurlon]

Every generator I have ever seen has circuit breakers on the output

If you draw too much they trip and current is interrupted

Tell that to the Homelite I was using. 1800w, when my trailer AC cycled while hot it'd stall the generator without tripping a breaker.

[BSR6]

Well the good news is it sounds like I'm being paranoid. My main concern was keeping it at 60 Hz since I've been told some devices will wear prematurely or even fail if not run at 60Hz and this got me thinking.

Overall my generator does a pretty good job of staying between 59 and 61 despite the varying loads (according to the meter), but frankly I hate relying on the generator's engine speed to keep things where they should be. This is the reason I was hoping for a simple solution such as a line conditioning power strip.

Thanks for the input.