Can power supplies/adapters be used to clean up dirty generator power?

[Steven B]

TL;DR Summary

Can electronic devices be used on "dirty" portable generators if the power is run through a power supply/adapter that converts the 120V/60Hz power to DC voltage to clean it up (for example, a laptop computer).

I have a portable generator that I use for backup power at my home in case of a loss of power. I understand that the power from these generators is not clean because both the voltage and frequency are not very stable and this is bad for sensitive electronics and may even damage them. I am wondering if this dirty power can be cleaned up by running it through a power supply that converts it to DC low voltage, as in the case of laptops and cell phones. It would seem to me that since most of these power supplies can take an input of 100-240V 50/60Hz, and output the correct DC voltage, this conversion process would clean up the power going to these devices (laptops and cell phones) and it would be OK to use these devices on generator power. I have not been able to find any information on this subject and I am hoping someone with an engineering background on this forum can help. Thanks.

 

[Baluncore]

Welcome to PF.
You might consider running a $100 VFD from your generator.
That will produce a well regulated voltage and frequency.
https://en.wikipedia.org/wiki/Variable-frequency_drive

 

[DaveE]

All good AC-DC power supplies will do this, that's their job. However, unregulated transformer-rectifier circuits, and really cheap poorly designed DC PSs may not. If your PS was sold with a name brand product (Apple, Lenovo, HP, LG, Samsung, Sony, Panasonic, etc.), I wouldn't be concerned. When we design these PSs we intend for them to work all over the world, which includes locations with really poor power quality. PSs and consumer electronics just can't break too often, or your company won't get really big like these did. If you bought the cheapest one on eBay, then I just don't know.

OTOH, you didn't actually say how bad your generator actually is. If you are seeing massive deviations in amplitude or frequency, then the solution is to fix or replace the generator, not so much to clean it up downstream. So, how do you know your power quality is bad, how bad is it and in which ways (numbers, please)?

 

[Steven B]

All good AC-DC power supplies will do this, that's their job. However, unregulated transformer-rectifier circuits, and really cheap poorly designed DC PSs may not. If your PS was sold with a name brand product (Apple, Lenovo, HP, LG, Samsung, Sony, Panasonic, etc.), I wouldn't be concerned. When we design these PSs we intend for them to work all over the world, which includes locations with really poor power quality. PSs and consumer electronics just can't break too often, or your company won't get really big like these did. If you bought the cheapest one on eBay, then I just don't know.

OTOH, you didn't actually say how bad your generator actually is. If you are seeing massive deviations in amplitude or frequency, then the solution is to fix or replace the generator, not so much to clean it up downstream. So, how do you know your power quality is bad, how bad is it and in which ways (numbers, please)?

Thanks for your reply. From what I have read, poor power quality is a fact of life for smaller portable generators. Most standby generators (permanently installed), even for residential use, will have automatic voltage regulation and thus much cleaner power (Generac advertises less than 2% THD), but most portables rely on a constant engine RPM to maintain clean power. If any larger load kicks on (in my case, my well pump is the largest), then the engine RPMs will drop momentarily and cause power issues such as voltage spikes and changes in frequency. Not a big problem for a motor but not good for sensitive electronics. I don't have any specifics regarding my generator but I assume it would also have these issues. I guess my question is just a general question of whether these types of power supplies can clean up this type of dirty power. Would you say that cell phone power adapters from the major brands would also be OK to use on generator power?

 

[anorlunda]

Not a big problem for a motor but not good for sensitive electronics.

Most electronics are not as sensitive as you think. Indeed, many of them say 110-240V, 50-60Hz on the nameplate. I have a lot of experience running laptop computers using portable generators. The electronics have never been damaged by the fluctuations in voltage or frequency.

 

[Steven B]

Welcome to PF.
You might consider running a $100 VFD from your generator.
That will produce a well regulated voltage and frequency.
https://en.wikipedia.org/wiki/Variable-frequency_drive

Most electronics are not as sensitive as you think. Indeed, many of them say 110-240V, 50-60Hz on the nameplate. I have a lot of experience running laptop computers using portable generators. The electronics have never been damaged by the fluctuations in voltage or frequency.

You may be right, especially in light of what DaveE wrote above, but I'm just curious, do you know if the generators that you used were the standard type or the inverter type?

 

[Rive]

I understand that the power from these generators is not clean because both the voltage and frequency are not very stable and this is bad for sensitive electronics and may even damage them.

Most sensitive electronics starts with converting that 'dirty' power to low voltage DC anyway. For low power devices, you don't have to be concerned (within the usual limits, of course).

By my understanding the real problem (if there is any) may start on the other end of the business. Though there is a regulation to limit this, some devices still drawing power in a very uneven way, thus creating disturbances even on a very 'clean' line voltage. Usually this is not a (visible) problem since on the grid these local disturbances creates negligible effect, but a generator is not the grid.

So, instead of suspecting the generator you better to look out for the attached devices first.

 

[anorlunda]

You may be right, especially in light of what DaveE wrote above, but I'm just curious, do you know if the generators that you used were the standard type or the inverter type?

Please start by answering DaveE's questions. It's not productive throwing opinions around without knowing what we are talking about.

So, how do you know your power quality is bad, how bad is it and in which ways (numbers, please)?

 

[Steven B]

Welcome to PF.
You might consider running a $100 VFD from your generator.
That will produce a well regulated voltage and frequency.
https://en.wikipedia.org/wiki/Variable-frequency_drive

I did some searching but every VFD I've seen is 3 phase output. Do they make them with 120V or 120/240V single phase output? Thanks

 

[anorlunda]

I did some searching but every VFD I've seen is 3 phase output. Do they make them with 120V or 120/240V single phase output? Thanks

Once again, why do you think you need better power?

 

[Steven B]

Once again, why do you think you need better power?

Because there is a lot of information from knowledgeable people who say power from portable generators can be a problem and I think it is not unreasonable to assume it could be a problem for my situation. However, as I stated above, I am asking a general question about whether these power supplies can clean up dirty power. I never said I need better power. I am just posing a question. Are you saying that power from portable generators is clean? If so, then I think you are wrong.

 

[anorlunda]

If you are determined to spend your money to buy "cleaner" power without any concrete definition of what clean means, or how clean is clean enough, then good luck.

I'm leaving this thread.

 

[Steven B]

If you are determined to spend your money to buy "cleaner" power without any concrete definition of what clean means, or how clean is clean enough, then good luck.

I'm leaving this thread.

Let me simplify it for you. Should any person be concerned when using electronic devices with an AC to DC power supply on a portable generator? That's the gist of it. That's all I want to know. I'm not planning to spend money for a solution. Baluncore was kind enough to make a suggestion about VFDs so I looked them up. It doesn't mean I am going to buy one. You are trying to make this into something it is not. Thanks for making a new member feel welcome.

 

[Klystron]

On the computer side consider installing a UPS (uninterruptible power supply) between mains or generator and the computer power supply. A typical retail UPS plugs into a wall socket charging an internal battery pack. Sensors detect various 'lapses' while a variety of filters remove spikes and other transients depending on the quality of the product and the replacement costs of the protected equipment. A UPS usually replaces or precludes using less expensive 'power strips' depending on the installation.

A single UPS can supply a laptop or workstation while also protecting attached devices such as phone/fax/modems and monitors. Scale the UPS accordingly. Data centers hosting multiple computers typically supply 'clean' AC and/or DC power to equipment racks on a contract basis.

 

[Steven B]

On the computer side consider installing a UPS (uninterruptible power supply) between mains or generator and the computer power supply. A typical retail UPS plugs into a wall socket charging an internal battery pack. Sensors detect various 'lapses' while a variety of filters remove spikes and other transients depending on the quality of the product and the replacement costs of the protected equipment. A UPS usually replaces or precludes using less expensive 'power strips' depending on the installation.

A single UPS can supply a laptop or workstation while also protecting attached devices such as phone/fax/modems and monitors. Scale the UPS accordingly. Data centers hosting multiple computers typically supply 'clean' AC and/or DC power to equipment racks on a contract basis.

I've actually looked into using a UPS. A double conversion type seems to be the best but if I can just plug a couple of devices on AC to DC power supplies straight into generator power then that would work for my purposes. Thanks

 

[Baluncore]

I've actually looked into using a UPS. A double conversion type seems to be the best but if I can just plug a couple of devices on AC to DC power supplies straight into generator power then that would work for my purposes. Thanks

Your fear, uncertainty and doubt, that generator power is “unclean”, cannot be immediately treated by the long slow process of education, so you need to buy a solution that makes you feel happy and confident.

A VFD or a UPS would meet that requirement, though they are probably quite unjustified from a technical analysis. It is a pity that it is VFD and UPS manufacturers who spread the fear of unclean generators, but that is the advertising that maximises their sales.

Your fear is real, you caught it from malicious advertising, but it is NOT based on a scientific analysis of your generator. If you cannot overcome that fear, then it will be quite debilitating, and will cost you real dollars for treatment with a VFD or UPS.

 

[Steven B]

Your fear, uncertainty and doubt, that generator power is “unclean”, cannot be immediately treated by the long slow process of education, so you need to buy a solution that makes you feel happy and confident.

A VFD or a UPS would meet that requirement, though they are probably quite unjustified from a technical analysis. It is a pity that it is VFD and UPS manufacturers who spread the fear of unclean generators, but that is the advertising that maximises their sales.

Your fear is real, you caught it from malicious advertising, but it is NOT based on a scientific analysis of your generator. If you cannot overcome that fear, then it will be quite debilitating, and will cost you real dollars for treatment with a VFD or UPS.

Thanks, but there is no "fear" involved and I have no plans to buy a UPS or VFD. It was a simple question about power supplies. We can debate whether portable generators put out dirty power or not but that was not really the point of my question. Maybe it is just advertising. I am willing to consider that possibility, but no one here has presented any evidence for that other than some implied "expertise". And I certainly don't need your patronizing attitude. Maybe you should go educate yourself on how to talk to people. I am learning that some people on this forum just seem to like the sound of their own voice. Some people come here to learn and instead some on this forum seem to take the opportunity to let them know how stupid they are for asking in the first place. I'm looking at you @anorlunda

I asked whether power supplies could clean up dirty power. You suggested a VFD for a 3 phase motor. So you want me to buy an expensive item that won't even help me? Really? Good suggestion. Instead, maybe you should have said "sure, just use the power supplies, but you may not even have an issue with dirty power". Thanks, "expert".

 

[Baluncore]

I asked whether power supplies could clean up dirty power. You suggested a VFD for a 3 phase motor. So you want me to buy an expensive item that won't even help me? Really? Good suggestion.

Single phase VFDs are available for very low prices, less than US$50. They are used for power supply conditioning and change of frequency. Really! it was a very good suggestion as it will keep you, and all your smaller adapters happy, without any need to assess each for compliance with your unspecified generator.

 

[DaveE]

I am asking a general question about whether these power supplies can clean up dirty power.

Yes.

Are you saying that power from portable generators is clean?

Sorry, this question doesn't make any sense to me. "Clean" is relative: Compared to what? Using what metrics?

 

[DaveE]

I am willing to consider that possibility, but no one here has presented any evidence for that other than some implied "expertise". And I certainly don't need your patronizing attitude. Maybe you should go educate yourself on how to talk to people. I am learning that some people on this forum just seem to like the sound of their own voice. Some people come here to learn and instead some on this forum seem to take the opportunity to let them know how stupid they are for asking in the first place.

Everyone that replied to you was volunteering their time, knowledge, and experience to try to help you. Otherwise, we have nothing to gain, nothing really to prove.

You will find in life that people may judge you based on how you communicate with others.
So, in light of that, I'm done, good luck.

 

[Averagesupernova]

Everyone that replied to you was volunteering their time, knowledge, and experience to try to help you. Otherwise, we have nothing to gain, nothing really to prove.

I'll say that I can empathize with both sides in this thread. I'll also say that comments like the above quote tend to be a turn-off. This thread is nowhere near long enough to play the 'we all volunteer here and you should appreciate us more' card. That's how I perceive it.
-
Regarding clean and dirty power, in a case like this, it should be assumed that it is desired that the output of the generator should be cleaner after going through a power supply type device. That's very subjective. It truly may be as useful as buying dinosaur repellent.
-
Where it gets interesting is what is suggested to use. I would be very careful about recommending a VFD. They vary quite a lot in how 'clean' their outputs are. I find it a bit ironic that the consensus here has been: "We are sure your power is likely clean enough." And then recommend something that would potentially make it worse. VFDs are built to drive 3 phase motors and I while I would trust them to regulate voltage and frequency quite well, I'd question the harmonic content. If the generator is working as intended by the manufacturer, I'd leave the VFD out. Use a UPS if the paranoia gets the best of you.

 

[Tom.G]

Since it is unknown how 'dirty' that generator is, specific, absolute, solutions remain an unknown.

That said, let's see if I can inject some background information here.

Generator and Well Pump:

• Pump turns on, voltage and frequency drops
  • Not usually a problem other than the lights momentarily dim
  • If using a laptop, then the internal battery handles that without problems
  • If using a desktop or anything without a battery, then it MAY shut down and reboot. That's a problem if it is writing to disk at the time. You may lose some data or have to re-install the operating system. A UPS battery backup will solve this. If you get one with 2 to 3 times the expected load capacity from a major manufacturer it will run the system for 5 to 15 minutes. Battery replacement cycle is about 2 years if you treat it gently, don't run it down, shut off system within 1 minute of the UPS switching On. When the UPS shows battery run time is 75% that of a new battery, order a battery; it has a few months of life left with a reduced run time.
• Pump turns off, voltage and frequency go up
  • COULD be serious depending on how high the voltage gets.
    • First line of defense is Surge Suppressor outlet strips; not the cheap ones. Look for those in a metal case and a pilot light that shows if the protection is active. Check the pilot light now-and-then and replace strip if it fails; buy some extras for spares and use them as needed.
    • Next step up is adding a UPS battery backup. Note I said ADDING, keep the Surge Suppressors strips even though the UPS has some built-in. There is often no indication when the internal Suppressor fails.
  
  A little more info in this post:
  https://www.physicsforums.com/posts/6554904
  
  Laptop and desktop computer power supplies are moderately tolerant of overvoltage and very tolerant of short term frequency variations. You can probably find their specs either in their manual or on the manufacturers website.
  
  However those 'wallwart' supplies for powering a Router or Switch for your internet connection, or charging you phone or tablet, are not as forgiving. You might want to keep spares around "just in case."
  
  Hope this helps!
  
  Cheers,
  Tom

 

[Rive]

Generator and Well Pump:

As a note: this example is about having a generator with unknown/irrelevant amount of 'dirt' in its power, and it is an attached device which muddies the 'water'.

 

[sophiecentaur]

Let me simplify it for you. Should any person be concerned when using electronic devices with an AC to DC power supply on a portable generator?

"any person" would need to specify the required limits for their supply quality before deciding whether or not to be "concerned". This is basically a 'how long is a piece of string?' question and I'm not surprised at some of the exasperated answers.

 

[AmericaN8]

hijacking this thread in part to help the OP as well as myself. I do know how dirty my generator is, its an old tecumseh and the sine wave looks more like chainsaw teeth than a sine. Is that ok for electronics?

 

[DaveE]

hijacking this thread in part to help the OP as well as myself. I do know how dirty my generator is, its an old tecumseh and the sine wave looks more like chainsaw teeth than a sine. Is that ok for electronics?

Probably ok for most stuff. But... How would we know without the details. Especially what you are connecting to it and what the waveform is vs. load current.

 

[sophiecentaur]

Is that ok for electronics?

It depends on what electronic equipment you'd be supplying. Professional equipment will use internal power supplies that clean up the incoming waveform and produce a steady DC voltage. If your generator is really that bad then you may have to deal with RFI (RF Interference) that could get to your equipment 'just through the air' (even for battery driven instruments).

Suck it and see could be the cheapest approach.

 

[AmericaN8]

It depends on what electronic equipment you'd be supplying. Professional equipment will use internal power supplies that clean up the incoming waveform and produce a steady DC voltage. If your generator is really that bad then you may have to deal with RFI (RF Interference) that could get to your equipment 'just through the air' (even for battery driven instruments).

Suck it and see could be the cheapest approach.

Its for my RV so things like AC unit, TV, fridge, sounds like laptops and phones will be fine.
The frequency is ok, minor deviations, Its not the smoothest running engine. The wave form is shaped a lot like a chainsaw link. um, it spikes high then trails off then drops to the opposite, spikes, trails etc. I wish i could show you, but i can't right now.

 

[anorlunda]

I can't recall a single case of actual damage due to dirty power from a portable generator.

Does anyone have a documented case of damage?

What about EMI resulting from dirty power?

 

[sophiecentaur]

What about EMI resulting from dirty power?

I'd bet the neighbours would be aware, as much as the OP. I remember my neighbours (young enthusiastic lads) chasing some interference into their attempts to record VHF radio programmes and we put it down to our ancient Hoover Vacuum cleaner. They could hear the motor and tied it to the impulsive interference. Sorted with some hand wound chokes and some capacitors.

Life is about to change in that respect. Solar panels and storage batteries will be used for low power electronics and the gas guzzling home generators may go out of fashion before too long.

 

[berkeman]

The wave form is shaped a lot like a chainsaw link. um, it spikes high then trails off then drops to the opposite, spikes, trails etc.

How did you measure the wavedform? Did you use a battery powered oscilloscope or similar?

 

[berkeman]

I can't recall a single case of actual damage due to dirty power from a portable generator.

Does anyone have a documented case of damage?

Not so much damage, but interference with wired communications like Ethernet cabling or control network cabling. Doesn't sound like that applies to this RV application, though.

 

[AmericaN8]

I used a regular 110 o-scope but it was plugged into city power with perfect sine wave at 60.00hz.
It could have been a coincidence but i did this odd job for a temp agency years ago where we were repairing cracks in cement. The company got a new portable generator and new dewalt grinders. Two or three grinders burned up after just a few days. Then they got a nice inverter generator and no more grinders burned up. I don't really know the cause for sure, it could be a combination of being underpowered and the cement dust. but i do know that those arent concidered sensative electronics. Pretty sure they were brushed on/of switch controlled.

 

[berkeman]

I used a regular 110 o-scope but it was plugged into city power

Just be careful using a regular grounded o'scope when probing AC Mains power. Beyond the safety considerations, you need to understand what the "ground" is for the o'scope power cord versus the ground for the o'scope probe lead. If they are not the same "ground", you can let the smoke out of your 'scope probe...

Update -- a good example is when you might try to repair one of the old "hot chassis" TV sets from back in the stone age. Very important to understand when to use isolation transformers in that kind of work.

 

[AmericaN8]

Not so much damage, but interference with wired communications like Ethernet cabling or control network cabling. Doesn't sound like that applies to this RV application, though.

nah, i mean i would anticipate some interference, but this is for emergencies and boondocking. I just want to be sure my electronics won't be damaged and i really don't want the a/c or fridge to be damaged. those are very expensive.