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post #1 of 7 (permalink) Old 09-15-2019, 10:08 PM Thread Starter
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Inverter Frig, etc. power conditioning

Didn't want to hijack the original thread this came up in:

https://www.powerequipmentforum.com/...ng-fridge.html

The information presented in that thread was informative and very interesting. Thanks Predator and Tabora.

This information presents a warning or wake up to those of us with older "open frame" gensets and have lockouots, etc. in place ready for outages. In my case I've used Generac "open frame" for years and Freezer, Frig, TV's, computer's, etc. have been fine. I'll certainly be sure not to buy an inverter frig when replacement time comes. That's assuming that we have the option "down the road." Generally speaking my small engine equipment lasts a long, long time, not sure I want to buy an inverter genset if I have to replace a frig or freezer. I don't agree that inverter gensets are needed for tv, computer, etc. use, they're shipped all over the world and exist quite well on "dirty power." It's a fundamental fact that the more complexicated you make anything the more often it breaks down. The "open frame" units are relatively simple, can be stored for weeks or months and perform as required with only routine maintenance. Now we have the inverter units which do offer a lot of desirable features but are much, much, more complicated.

Also wondering about all the folks who have gone with the whole house, transfer switch back up power. e.g. Generac units which are not inverter type, I'm sure they'll be buying new Frig's which have the new inverter technology.

As a retired engineer, there's something fundamentally wrong about requiring an inverter to feed another inverter. I've seen similar overkill in military and other critical operations, but there were technicians and lots of spare parts standing by to keep everything happy.

Wondering if anyone has investigated "point of use" power conditioning modules for the new frigs, freezers, etc.? Capacitors have long been used to "smooth" power, wondering why the manufacturers of these new units didn't provide them?

Thanks for your time,

Ev
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post #2 of 7 (permalink) Old 09-19-2019, 01:03 PM
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Here's the waveform from an open frame Genset




And here is what your appliances and electronics really want.....



The difference is THD and surging.

To the best of my knowledge......
The biggest problem with non inverter generators is power surges. Those can zap electonics. A lot of electronic components have specific voltage tolerance ranges.

Non inverter generators must run at a specific RPM to create the Hertz needed. In the US that is 60Hz...and that speed is exactly 3600rpm.

Because motors on generators are often not precisely governed, but instead use springs or simple governing methods, electrical spikes occur when the motor stumbles for example then surges to recover..
So a non inverter generator with a sophisticated speed control system would work better, but still not as good as an inverter generator.
I would venture a guess that your Generac non inverter generator has a better speed control system than my Coleman Powermate circa 2004.


The other problem is Harmonic Distortion, which causes an increase in Current, thereby creating heat. Heat is the enemy of sensitive electronics.
Electronics were designed to operate on Sinusoidal current. The further from that, the greater the THD. I don't have samples of power quality in various countries but
it is likely that most developed nations have the capability to generate AC power with THD of 6% or less, the generally accepted threshold of clean vs "dirty" power.
Again, not all generators are created equal. If you buy a high end NON Inverter generator with precision electronics and a high quality alternator, your power is probably less "Dirty"
that less expensive non inverter generators. 10-15% THD (or more) is common in non inverter generators.

So it's probably not completely accurate to say "appliances will be damaged" by non inverter generators, but maybe it is more accurate to say it is less likely that appliances will be damaged by non inverter generators. Or that Inverter generators are more likely to provide AC that is within the specifications required by appliances.

No doubt, to some degree, most quality appliances have some built in filter circuitry to help suppress some of that. However, above 6% even the filtering circuitry will suffer from additional heat.

YMMV (And an EE can certainly correct me as needed)

https://www.aptsources.com/wp-conten...er-Systems.pdf

Quote:
Harmonic distortion can have detrimental effects on electrical equipment. Unwanted distortion can increase the current in power systems which results in higher temperatures in neutral conductors and distribution transformers. Higher frequency harmonics cause additional core loss in motors which results in excessive heating of the motor core. These higher order harmonics can also interfere with communication transmission lines since they oscillate at the same frequencies as the transmit frequency.3 If left unchecked, increased temperatures and interference can greatly shorten the life of electronic equipment and cause damage to power systems

To clarify - I'm not a Predator, but one of my Generators IS
HarborFreight Predator 3500 Inverter

Last edited by Predator; 09-19-2019 at 01:15 PM.
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post #3 of 7 (permalink) Old 09-19-2019, 01:08 PM
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Quote:
Originally Posted by exmar View Post

This information presents a warning or wake up to those of us with older "open frame" gensets and have lockouots, etc. in place ready for outages. In my case I've used Generac "open frame" for years and Freezer, Frig, TV's, computer's, etc. have been fine. I'll certainly be sure not to buy an inverter frig when replacement time comes. That's assuming that we have the option "down the road." Generally speaking my small engine equipment lasts a long, long time, not sure I want to buy an inverter genset if I have to replace a frig or freezer. I don't agree that inverter gensets are needed for tv, computer, etc. use, they're shipped all over the world and exist quite well on "dirty power." It's a fundamental fact that the more complexicated you make anything the more often it breaks down. The "open frame" units are relatively simple, can be stored for weeks or months and perform as required with only routine maintenance. Now we have the inverter units which do offer a lot of desirable features but are much, much, more complicated.

Also wondering about all the folks who have gone with the whole house, transfer switch back up power. e.g. Generac units which are not inverter type, I'm sure they'll be buying new Frig's which have the new inverter technology.

As a retired engineer, there's something fundamentally wrong about requiring an inverter to feed another inverter. I've seen similar overkill in military and other critical operations, but there were technicians and lots of spare parts standing by to keep everything happy.

Wondering if anyone has investigated "point of use" power conditioning modules for the new frigs, freezers, etc.? Capacitors have long been used to "smooth" power, wondering why the manufacturers of these new units didn't provide them?

Thanks for your time,

Ev

I see absolutely no reason you can't run an Inverter Fridge or appliances with an Inverter Generator. The appliances should be very happy in fact

The other big advantage to Inverter generators is to your ears. Many non inverter generators are really noisy.
Also fuel consumption.
Since inverter generators aren't RPM bound, you can have your Inverter generator drop down in speed when the load decreases.

As far as conditioning the output from non inverter generators, I've been looking into the use of large capacitors to smooth things out.
.
.
ymmv

To clarify - I'm not a Predator, but one of my Generators IS
HarborFreight Predator 3500 Inverter

Last edited by Predator; 09-19-2019 at 01:10 PM.
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post #4 of 7 (permalink) Old 09-20-2019, 12:45 AM Thread Starter
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Excellent discussion Predator, however, I'll stick with what I have, and continue to monitor via this forum and other sources inverter generators. I just looked at the Generac site to see what they offer in this area, looks like the largest is 3500W. I believe Generac is one of the major players in this area and they don't "yet" offer anything larger than that. My perception of inverter units is they're portable, quiet, and offer clean power and are popular for camping, tailgating, etc. I'm not aware that they're designed to to supply 110/220 via an L14-30 into a load center via generator interlock, etc. which I believe is in common usage.

In any event, I'm sure we're all happy with what we've worked out for our outage needs.
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post #5 of 7 (permalink) Old 09-20-2019, 07:47 AM
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There are Inverter Generators with L14-30 interlock.

The Honda EU7000is and Yamaha EF6300isde for example.
Yamaha EF6300iSDE Inverter Portable Generator Review - Power Up Generator

Though neither is inexpensive.

In no way am I suggesting anyone "has" to change their generator.
Simply presenting information to the best of my knowledge.


Information is power...(just not AC)....hope it helps someone.

To clarify - I'm not a Predator, but one of my Generators IS
HarborFreight Predator 3500 Inverter
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post #6 of 7 (permalink) Old 09-20-2019, 08:06 AM
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One other thing about Inverter Refrigerators.......

It appears that only the compressor is fed by an inverter and not all of the remaining electronics. They seem to be called, Digital Inverter Compressor Refrigerators"
So I'm not sure if all Inverter Refrigerators are the same, or if I even fully understand the schematics......but so far from what I've gathered the only component that would be protected would be the compressor.

https://news.samsung.com/global/how-...n-refrigerator

If that's the case, then "Dirty Power" would still be of potential harm to the refrigerators main power panel, fan motors and any other sensitive electronics of these Inverter Refrigerators.

The key word is "Potential". Any non inverter generator capable of producing AC with 6% THD or less, and no voltage spikes should work fine.

To clarify - I'm not a Predator, but one of my Generators IS
HarborFreight Predator 3500 Inverter
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post #7 of 7 (permalink) Old 09-22-2019, 03:11 PM
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Update on Inverter Refrigerators..
After speaking with people who are very electronics knowledgeable, Inverter refrigerators do not have "Inverters" in the same sense that Inverter Generators do.
Apparently, the term is being broadly used to refer to a variable speed compressor. Not one driven by an inverter that converts AC to DC, then back to AC.

in addition, at least one said that having this extra circuitry would make Inverter Refrigerators MORE prone to failures from dirty power, not less prone.


In no way am I placing judgement on anyone's generator or suitability for any particular use. I'm just relaying information as I gather it.

That's all I have for now.
Your Mileage may vary of course.

To clarify - I'm not a Predator, but one of my Generators IS
HarborFreight Predator 3500 Inverter
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