Generator question: Is flickering power bad for a fridge?

[Fxc2hh]

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]

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]

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]

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]

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]

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]

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]

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]

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]

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

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

[kwinn]

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

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

[JeremyJ]

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]

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]

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]

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]

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]

/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