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Fxc2hh
08-29-2011, 02:20 PM
My neighbor bought one of these generators and when he uses it, the lights in his house flicker because the electricity isn't "regulated". My question is whether this could damage your refrigerator because the fridge has a compressor and everything in a compressor is under pressure. I read that you can't turn some air conditioners off and then on again without waiting three minutes because you could damage them. Can it damage a fridge?

http://www.harborfreight.com/engines-generators/gas-engine-generators/800-rated-watts-900-max-watts-portable-generator-66619.html

What do you think?

localroger
08-29-2011, 02:22 PM
It's unlikely to damage the refrigerator. You can burn up an A/C compressor by starting it before the pressure has bled off from its last cycle but the voltage variations of a generator are unlikely to do that. However, you CAN damage electronics such as computers, TV sets, and so on with that kind of power source.

bomber
08-29-2011, 02:45 PM
Add a 120V AC electrolytic capacitor across hot and neutral. that SHOULD stop the flickering. You might be able to order one online somewhere, but I got mine from a broken air conditioner (one from the condenser unit, and one to start the main blower fan).

Fxc2hh
08-29-2011, 03:02 PM
Add a 120V AC electrolytic capacitor across hot and neutral. that SHOULD stop the flickering. You might be able to order one online somewhere, but I got mine from a broken air conditioner (one from the condenser unit, and one to start the main blower fan).

Can someone draw me a simple diagram on how to hook it up. A neighbor has an extention type cord wired into his electric and he has a way of switching the power. An electrician has seen it but I don't know if the same electrician approved it. I may want one of these generators to run a sump pump or power my fridge as we just went through Hurricane Irene.

Does Mouser or Digikey carry a capacitor that is suitable?

bill190
08-29-2011, 03:14 PM
A refrigerator compressor is just an electric motor. And contractors have used generators of all types and sizes on construction sites for years to power all sorts of electric motors. I've not read about any problems with these except when people do not use a large gauge extension cord. Then there is a voltage drop problem (use 12 or 10 gauge for long cords.)

Although I have read a ton about people who have had problems with their electronic things and generators. And newer refrigerators have electronics in them! So that could be a problem.

Recently they have come out with "electronics friendly" generators. Search google.com for the words (including quotes)...

"electronics friendly" generator

Another solution is an "online" "true sine" UPS. These create their own "perfect" electricity 100% of the time. Other UPS only create electricity when running on the batteries, but pass through the mains electricity when not on battery. The word "online" means 100% of the time. So search google.com for the words (including quotes and +)...

+online +"true sine" +UPS

I've not had luck searching for "power line conditioners". There is a lot of "sales hype" with some of these which are just power strips. And the larger power line conditioners cost a small fortune or will be for 3 phase industrial use.

bill190
08-29-2011, 03:19 PM
P.S. A common probelm with generators is people try to run too many things at the same time.

Look at the wattage on the generator. And convert amps to watts for appliances with the following calculator. Use Single Phase...

http://www.jobsite-generators.com/power_calculators.html

Mark_T
08-29-2011, 03:54 PM
Also generators are not usually rated for a varying load, so a 2kW generator which can run 2kW of lighting won't cope well with 2kW of _theatre_ lighting which needs to change frequently. You would typically want to derate a generate for a varying load.

The dangerous failure mode for a fridge is when the mains supply goes too low for a long time - the motor stalls and then overheats, potentially then bursting and catching fire. Since it is immersed in an oil bath so it is an effective incendiary device (note that the refrigerant under pressure is not the issue). However power generating companies are well aware of the dangers of such brown-outs and the network should automatically trip out if this happens. With your own generator this is your own responsibility (a good generator control circuit will do the right thing and protect against under and over-voltage.)

I suspect modern efficient fridges have much less powerful motors than in the past and are less likely to be able to overheat to the point of failure. Googling suggests fridge-related fires are rare.

alex123
08-29-2011, 06:06 PM
Add a 120V AC electrolytic capacitor across hot and neutral. that SHOULD stop the flickering. You might be able to order one online somewhere, but I got mine from a broken air conditioner (one from the condenser unit, and one to start the main blower fan).

I would NOT connect these (and any other ones) capacitors across 120V AC unless you're up for a big KABOOM. Make sure that you're far away when you turn on the AC. You may film that too. It may actually be a hit on youtube.
Seriously though... These AC caps are used as the AC motor starters and/or run capacitors. NEVER connect them directly to the AC hoping to smooth out the voltage level like for DC.

kwinn
08-30-2011, 04:49 AM
I would NOT connect these (and any other ones) capacitors across 120V AC unless you're up for a big KABOOM. Make sure that you're far away when you turn on the AC. You may film that too. It may actually be a hit on youtube.
Seriously though... These AC caps are used as the AC motor starters and/or run capacitors. NEVER connect them directly to the AC hoping to smooth out the voltage level like for DC.

I am so glad you posted that and I second that advice.

Fxc2hh
09-01-2011, 01:15 AM
I am so glad you posted that and I second that advice.

I will stay safe and agree with both of your advice.

kwinn
09-01-2011, 03:22 AM
I will stay safe and agree with both of your advice.

Good to hear. Wouldn't want to loose any forum members.

JeremyJ
09-01-2011, 08:02 AM
It'd be interesting to see how your neighbor is connecting that generator to his service panel....hmmm. Given the size of the generator, I'd guess that the flicker in the lights is resulting from temporary slowing of the generator as the single cylinder, 2-stroke engine starts its compression stroke. This could cause a voltage fluctuation in the power signal at a frequency below 60Hz. An oscilloscope connected to an available outlet would tell an accurate story of what is happening. Given the low power requirement for the lights, he could use an UPS to clean up the power on the lighting branch of the circuit (not exactly NEC practice, but...) - also would not recommend connecting anything expensive like a LCD TV, etc. without an UPS. The refrigerator motor shouldn't be an issue - probably a universal motor, and I imagine the insulation rating is 300V. The only possible danger would be additional mechanical stress on the motor, particularly the bearings, but this is something that would occur over a long period of time.

Loopy Byteloose
09-01-2011, 09:10 AM
The fact that your neighbor is using an extension cord on a refrigerator or a generator is another red flag. These are heavy amperage devices and often extension cords are not as heavy duty, and of course a significant length creates a voltage drop.

Nonetheless, refrigerators are rather old technology that generally accommodates brown outs and voltage spikes better than solid-state devices.

As a kid, I learned the hard way that a capacitor inserted wrongly into an A/C line is equal to a short circuit. I blew up an AC outlet and the capacitor in my Elementary Electronics course and the teacher was livid. If the same capacitor was used on a DC circuit, it might reduce the flicker - but one MUST get very clear about the differences of AC and DC when using coils and capacitors.

Fxc2hh
09-01-2011, 12:05 PM
The fact that your neighbor is using an extension cord on a refrigerator or a generator is another red flag. These are heavy amperage devices and often extension cords are not as heavy duty, and of course a significant length creates a voltage drop.

There are different guage wires in extention cords. The old long orange ones are good enough to run an electric lawnmower on. I've run an electric snowblower on them and haven't noticed a difference between that and 13 or 15 guage extention cords.

Loopy Byteloose
09-01-2011, 12:25 PM
Here is Taiwan, they love to make items look just like the heavy duty version - but withhold costly material. Just because a cord is orange doesn't assure the gage of the wire inside. Household wiring is usually 12 or 14 gage solid copper wiring, sometimes 10 gage. Running a 16 or 18 gage extension cord is likely to upset the whole scheme by added resistance, even if the cord is short and in good condition. Having a generator feed a whole house which minimally have a 60amp serviice mains is rather ridiculous in the first place and many newer homes are 120 amp service mains. Add an extension cord between the generator and the home, you just have that much less to offer.

If you must use an extension cord because you want to keep the generator outside (to prevent carbon monoxide poisoning and noise), it is far better to set up a separate limited power distribution than to try to drive the whole home. Somebody that doesn't understand electrical distribution is likely to turn more things on. Alternatively, shut down unneeded circuits at the circuit breaker box if you must use the house wiring to distribute power AND consider using some ROMEX (with nice solid copper 12 gage wire) to connect the generator to the house service.

Fxc2hh
09-01-2011, 12:38 PM
Here is Taiwan, they love to make items look just like the heavy duty version - but withhold costly material. Just because a cord is orange doesn't assure the gage of the wire inside. Household wiring is usually 12 or 14 gage solid copper wiring, sometimes 10 gage.

The old extention cords made in Mexico were sufficient. Now Lowes sells extention cords made from China and I can tell the difference so I buy them from Home Depot which gets their cords made from the Phillipines which is a little heavier.

I have a bunch of broken extention cords that I have to fix because I cut them accidentally with the hedge shears.

But we're talking about the power going out for 2 1/2 hours to five hours and having to run a sump pump for a time if the neighbor's basement gets filled by a creek. It is running a device to help maintain the temperature. My mother in law's power went out for 11 hours and she still had ice cubes because she doesn't open the fridge. We're talking about running it a little to maintain the temperature or having a light but nothing long term.

stamptrol
09-01-2011, 02:22 PM
/mini rant ON
I must admit I sometimes despair at how quickly bad and dangerous advice slides into discussions. Thankfully not often here.

The little gen set the OP linked to is a fine product and will run the referred to refrigerator for years without causing any damage. The "flickering" is just the little generator momentarily bogging down as the compressor cycles. Ironically, the cheaper gen sets handle heavy starting loads (proportional to their capacity) better because their less technically advanced voltage regulators allow the voltage to sag to give the same effect as a reduced-voltage starter.

The suggestion of the capacitor as a solution just boggles the mind in its glaring lack of understanding. Luckily, it was noted and I think the message received. And, suggesting a household refrigerator compressor would blow up in an oil-fueled firebomb under low voltage is a good topic for a sci-fi story but bears no relationship to any normal fridge compressor with built-in thermal overload and fed by a circuit breaker/fused circuit.

As has recently been discussed in other parts of the forum, sometimes conjecture and ad-libbed urban legend does not add to the Op's search for answers.
/mini rant OFF

Tropicman
12-10-2013, 10:53 PM
Hi Techies, I have a related question.

We have a new Samsung fridge which no doubt contains more electronics than my office desk.

I may need to run this on an old Kawasaki non inverter type generator. It works fine with the washing machine which has an electronic power board but It will not work a desktop PC run through a UPS power box.

What do you think the risk is of running the new fridge on the old gen set?

Regards,

Tropicman

Peter KG6LSE
12-11-2013, 03:14 AM
I would NOT connect these (and any other ones) capacitors across 120V AC unless you're up for a big KABOOM. Make sure that you're far away when you turn on the AC. You may film that too. It may actually be a hit on youtube.
Seriously though... These AC caps are used as the AC motor starters and/or run capacitors. NEVER connect them directly to the AC hoping to smooth out the voltage level like for DC.


@Stamptrol Yes and no for all the wrong reasons .!


AC EE101 . Power factor correction .
Gen sets Like a PF of 1 ...... Esp the inverter ones !!!!!!!!!!!!!

So adding a cap for PFC is not a bad idea IF the end user does some AC math .

that said the idea of a HUGE cap on the line is bad bad bad . and using a polarized cap is just a nasty .

most of those non oil caps are not rated to run continuously with AC on them .
they are Starting caps ......... Oil filled ones are known as running caps ( used to make a phase shift in a AC single phase motor) and are AC rated .

the latter If with math may be OK as PFC caps !!!!!!!

many new CFLs and PC PSUs are PFCed ..
However you again need to do Trig to get the right cap..


Simply put . you shove a 2000 uf cap accros a AC Line . its gonna look like close to a short .

Peter KG6LSE
12-11-2013, 03:35 AM
It'd be interesting to see how your neighbor is connecting that generator to his service panel....hmmm. Given the size of the generator, I'd guess that the flicker in the lights is resulting from temporary slowing of the generator as the single cylinder, 2-stroke engine starts its compression stroke. This could cause a voltage fluctuation in the power signal at a frequency below 60Hz. An oscilloscope connected to an available outlet would tell an accurate story of what is happening. Given the low power requirement for the lights, he could use an UPS to clean up the power on the lighting branch of the circuit (not exactly NEC practice, but...) - also would not recommend connecting anything expensive like a LCD TV, etc. without an UPS. The refrigerator motor shouldn't be an issue - probably a universal motor, and I imagine the insulation rating is 300V. The only possible danger would be additional mechanical stress on the motor, particularly the bearings, but this is something that would occur over a long period of time.


how would a normal UPS help ?


Bill has it right .

unless its a $1000 Line Interactive or ONLINE UPS .
a normal UPS is not gonna do any good .......


Hi Techies, I have a related question.

We have a new Samsung fridge which no doubt contains more electronics than my office desk.

I may need to run this on an old Kawasaki non inverter type generator. It works fine with the washing machine which has an electronic power board but It will not work a desktop PC run through a UPS power box.

What do you think the risk is of running the new fridge on the old gen set?

Regards,

Tropicman


Okay soo Again with out knowing the max and min on the power supplys that run the fancy parts of the fridge . I have no way to put a risk assement on it . However ....

If the PSU that runs the fancy stuff can take 170V or more then I would not worry .provided your genset is is goood order ....... I need more data Really .......

you really need to \ weagh the price of a new fridge VS the food in it VS the reason your lacking mains power ......

CuriousOne
12-11-2013, 04:03 AM
I was also experiencing "flicker" with relatively low powered generator, when powering electronic devices. I've connected PFC choke removed from PC power supply in line with generator, and flickering was gone.

Phil Pilgrim (PhiPi)
12-11-2013, 05:27 AM
When I bought my house in 1984, it came with an already-ancient Sears Coldspot refrigerator. Sometimte in the mid-90s, the compressor crapped out. It would not start; it just sat there and hummed. I went to the local appliance store, and they told me I did not need to replace the compressor and, instead, sold me a "start booster", which I wired in ahead of the compressor. Here it is 20 years later, and the fridge still works like a champ. It's a good thing, too, since old-style compressors are far superior to the new ones. The old ones are sealed units which actually run in the coolant that they pump, thus preventing overheating and extending their service life.

Anyway, the point of bringing this up here is that, if you suffer from fluctuating or fading voltage, it might be advantageous to add a start booster to the compressor to make sure it starts under adverse conditions. I don't recall the one that I purchased being very expensive, and it's kept my old workhorse alive all these many years later.

-Phil

davejames
12-11-2013, 05:48 AM
Mr. Pilgrim - mi no habla "start booster".

'Splain por favor?

Phil Pilgrim (PhiPi)
12-11-2013, 05:59 AM
I wish I could give a technical explanation, but I can't. It's just magic. I can speculate, however. The compressor motor is apparently driven by a capacitive starter. As the motor ages, the bearings wear, or the capacitors become "incompacitated" [ahem], the normal start voltage/current is insufficient to get it turning from a dead stop. The "start booster" somehow adds a little extra oomph [technical term] at startup to get the motor turning. (If you suspected before that I'm not an AC motor expert, you should by now be certain of it.)

-Phil

potatohead
12-11-2013, 06:41 AM
re: Gauge and appliances / tools.

Depends on the length and the load, and what the device is built for. The better ones incorporate the thinner wires and a suitable length into the design.

Personally, for anything over about 20-30 feet, I run 10 gauge cords. They aren't cheap, but I've never, ever had anything fail or run poorly up to 100' (two 50' in series.) Most often, I'll just lead out with the 10, and then use an ordinary one from there.

A similar thing goes for house wiring. I've noted a trend in newer homes to settle on 14 gauge wire almost everywhere. For a larger home, and a few junctions in the circuit, there is a considerable drop! I'll see them do it on 15A circuits too, which blow early due to that drop, and it's not approprate if a 15A socket needs to be dropped in somewhere.

The last one I did saw 10 gauge from the breaker to the room junction, unless it's a short distance, then I used 12. From that junction to the outlets, I used 12, and then 14 to connect a few short distance, parallel wired outlets. Honestly, the difference in wire cost wasn't all that much, given some planning. The nice thing about doing it that way, is you generally exceed local code requirements, and if a 15A socket is needed somewhere, you've got it covered.

Lights a bit brighter, portable heaters not blowing breakers, etc... And nice, cool, long lasting circuits. Nobody wants to tear into that stuff. And on the off chance somebody pushes it someday, the wires are there to handle it. The home I'm in right now was done with 12 & 14, and it's kind of crappy. One of these days... :)

Again, for nicer tools and appliances, they've designed it well, basically reducing the need or benefit from the larger diameter wires and cords. These days, I'm seeing way too many cheap-o things that do not perform well, or generate excessive heat at more than average room length distances on smaller diameter wire. After I lost a drill assembling a fence, that was it for me.

I would worry about any real length on those smaller diameter wires when using a generator. Maybe it's just me, but I like to run the bigger stuff. Buy it once, and you've got it, unless something bad happens.

@Phil: Never heard of such a thing! I have two units with the sealed compressors and they are getting older. So far, they've performed fine, and that may be due to my preferences on wiring to them above, but I'm filing this info away for when I will need it someday. Seems like a great "life extension" option for older, but perfectly servicable appliances. I have an older "coffin" style freezer that gets right down to about 10 degrees F. Love that thing. Quiet, and old. Would hate to replace it and it's been in service for a very long time.

Loopy Byteloose
12-11-2013, 03:44 PM
P.S. A common probelm with generators is people try to run too many things at the same time.

Look at the wattage on the generator. And convert amps to watts for appliances with the following calculator. Use Single Phase...

http://www.jobsite-generators.com/power_calculators.html

Another problem is that people think nothing of setting the generator far and away to minimize noise and carbon monoxide, and then run 100 feet of rather flimsy extension cord to what they expect to power. A refigerator is a rather demanding load.... needs a better than average extension cord.

GordonMcComb
12-11-2013, 04:44 PM
Phil, Your electric rates must be pretty low. A 30 year old fridge has gotta have pretty low efficiency.

davejames
12-11-2013, 04:56 PM
It's just magic.
-Phil


...THAT I can understand! :lol:

Phil Pilgrim (PhiPi)
12-11-2013, 05:38 PM
Phil, Your electric rates must be pretty low. A 30 year old fridge has gotta have pretty low efficiency.
And it was already old when I moved here. So more like 45-50 years old, I'm thinking. Hmm. Maybe that explains my rather high electric bills...

-Phil

Don M
12-11-2013, 06:10 PM
I wish I could give a technical explanation, but I can't. It's just magic. I can speculate, however. The compressor motor is apparently driven by a capacitive starter. As the motor ages, the bearings wear, or the capacitors become "incompacitated" [ahem], the normal start voltage/current is insufficient to get it turning from a dead stop. The "start booster" somehow adds a little extra oomph [technical term] at startup to get the motor turning. (If you suspected before that I'm not an AC motor expert, you should by now be certain of it.)

-Phil

I used to sell / service appliances for many years. Here's an example of what you most likely used. I've used many of these over the years-

http://www.amazon.com/Supco-RCO810-Capacitor-Overload-Device/dp/B004XS1P5E

They are sized by the HP of the compressor. Supco is a large supplier in the aftermarket parts for appliances. Just google Supco 3-n-1.

JordanCClark
12-11-2013, 06:56 PM
Don beat me to it with a link, but they're called hard start kits. Basically it's a larger start capacitor to put some extra current on the start winding. Most will have a PTC thermistor in it to remove the start winding from the circuit. I've heard about claims of reduced inrush, but I personally haven't verified it one way or the other. On the other hand, Phil's compressor is still alive and kicking, so there may be some truth to it.

GordonMcComb
12-11-2013, 08:14 PM
And it was already old when I moved here. So more like 45-50 years old, I'm thinking. Hmm. Maybe that explains my rather high electric bills...

You can pick up a Kill-a-Watt at Harbor Freight for $20, and see what it pulls over a day's period. Handy little thing. Using one now to help us decide which of two fridges to keep using, and which to Craigslist.

Phil Pilgrim (PhiPi)
12-11-2013, 08:31 PM
You can pick up a Kill-a-Watt at Harbor Freight for $20, and see what it pulls over a day's period.
That would entail pulling the fridge out from the wall to plug it into the little gizmo. 'Not sure I really want to see what's back there after all these years! :)

Seriously, though, thanks for the tip. I plan to order one as it sounds pretty handy.

-Phil

Rforbes
12-12-2013, 12:17 AM
In regards to the initial question: YES you can, and WILL, damage your fridge. If the lights are flickering while powered by a generator, then that generator is:

1-under-sized for the load it's connected to. (most likely)
2-Has a static voltage regulator which isn't capable of maintaining the appropriate voltage under the connected load. (common, but not as likely as #1)
3-If it actually has an automatic voltage regulator (extremely unlikely) it's faulty and isn't adjusting the voltage properly. (avr's are almost non-existent in small
generator sets)

The most probable cause of the lights flickering is an under-sized generator set. Many professional electricians don't understand how to properly calculate loads and and even more commonly, customers don't understand the limitations of the generator set after it's installed and they overload them.

The reason this can, and WILL damage your fridge is because any time you see your lights flickering, you're either consuming power at about 42 hertz (or less) or your voltage has dropped to around 80 volts or less (assuming a single phase 120VAC circuit.) Or both. And either of these conditions is immediately causing a mild-to-severe overcurrent condition on your compressor motor. Sure, it might run a couple years with the occasional brown out or automatic re-try (which are common utility-side power problems) but you're definitely doing it no favors by running it in conditions like what was described originally.

Concerning restarting the compressor too quickly after it's been shut off: yep, it's bad. Most refrigerant systems nowadays have lockout timers. It's bad for several reasons, and those reasons have more or less drastic effects depending on the type and design of the refrigerant circuit.

Also- attempting to "hook up a capacitor" to a generator set is very doable- it's called power factor correction. If you have the requisite knowledge to do so, you'll also have the knowledge to realize it's not worth doing on an isolated bus (which is what you'd call a generator set powering your home, because it's the sole source of energy when it's connected to the load.) Since the load changes every time something turns on or off, so does the power factor of that load. So one set of capacitors will only help significantly under a specific load condition. Generally, the only thing you'll get is a more leading power factor (towards unity from the lagging side) or potentially a leading power factor (past unity, into the leading side) on the generator. This condition will overheat your windings, stator and rotor, and will most likely damage the voltage regulator. And lastly, if you were able to use capacitors to create a unity power factor (again- doable but bad practice) you'd be creating so many harmonics on your system that you'd start damaging other electronics the generator is connected to.

A properly sized, good quality genset for the location in question is the right way to go. At very least, a load that is well within the capabilities of the generator set (rms wattage, power factor, starting va, etc)

Peter KG6LSE
12-12-2013, 12:20 AM
Also- attempting to "hook up a capacitor" to a generator set is very doable- it's called power factor correction. If you have the requisite knowledge to do so, you'll also have the knowledge to realize it's not worth doing on an isolated bus (which is what you'd call a generator set powering your home, because it's the sole source of energy when it's connected to the load.)

Exactly what I was trying to say.!

@ all

The Kill O watt is one tool no geek should be with out ...... VA ( KVA ) PF Watts and amps and Hz and Volts .

I have 2 . one is the EZ verison for my segway and one is just in my tool bin that I added a cord too so that it can be used Off the wall ( bettter to view the screen with )

I have compared them to the Fluke Over priced clamp on gizmos and the 19 buck meter is Spot on ! .

Its a very good limited voltage and current poor mans AC power meter and analyzer. ( sans fancy screen )

Rforbes
12-12-2013, 01:11 AM
Haha!! Just looked up the Kill O watt gizmo. Neat. :)