small office fridge makes desk lamp flicker briefly

Discussion in 'General Electronics Chat' started by Charles Flux, Apr 5, 2007.

  1. Charles Flux

    Thread Starter New Member

    Aug 2, 2006
    6
    0
    Hello everyone,

    I have a situation in my home office where I have a relatively small fridge that I like to keep there. While I'm working, my desk lamp flickers for an instant whenever the fridge's compressor starts up. It becomes too annoying to concentrate with this going on, so I've had the fridge unplugged. But I miss the fridge. What can I do to stop the desk lamp "flicker" from occurring? (I've thought about moving the fridge to a different circuit. But I'm not sure if that will a) solve the problem, or b) even be possible, because i'm fairly certain the entire office is on one circuit only. Thank you for your help...I appreciate any suggestion you may have to help me solve my problem.

    Charles
     
  2. kender

    Senior Member

    Jan 17, 2007
    263
    0
    Here's a hypothesis. When the compressor starts, the motor very briefly draws max current (stall current). May be motor start capacitor can help you. I use them always with DC motors, but I never had a cahnce to use them with AC motors.
     
  3. hgmjr

    Moderator

    Jan 28, 2005
    9,030
    214
    I don't know how much money you are willing to spend but you may want to consider using a small UPS (uninterruptable power supply) to power your lamp and your computer if you have happen to have one on your desk.

    I just checked on www.walmart.com and they carry some inexpensive ones costing in the 50$ range.

    hgmjr
     
  4. Charles Flux

    Thread Starter New Member

    Aug 2, 2006
    6
    0
    Thank you kender, for that idea. It actually occurred to me that a cap might be the component capable of "smoothing out" the current fluctuations in this case..trouble is, I'm a true beginner in electronics, and I'm still really in the "electricity stage" of my learning. I know about caps, dielectrics, how they work, etc. but havent actually taken apart a device like a fridge yet. So i'm not sure if im game enough yet to attempt to solder a cap into where it'd go in the fridge.

    The fridge is an Avanti. I'm going to see what info is available from them, as far as data sheet or schematic. But again, I have no idea where to "insert" the cap or what type of cap to use or its value (as far as rating, etc. my guess is that it should be rated for at least the max power (current) rating listed on the appliance. As for type of cap, I'd assume electrolytic, but again, not confident about this).

    Any suggestions on these points would be greatly appreciated. Thank you,

    Charles
     
  5. Charles Flux

    Thread Starter New Member

    Aug 2, 2006
    6
    0
    hmm...Seems like the most feasible idea (for me) of all!! Although $50 is a bit pricey for me at this moment. So a UPS in addition to back-up power when the lights go down, it has a "smoothing" effect? It would seem so to me, since a UPS provides a stable value of voltage under "sags" "brown-outs" or "spikes" in the power, as far as I recall. If this is true, then wouldn't just a standard surge protector do the job?? Since there's no "sagging" going on, just the "spiking" because of the compressor in the fridge?? If I plug the surge protector in the wall outlet and then plug the fridge into the protector, would the protector act to prevent the current "spike" going in this direction??

    I much appreciate your help in solving this problem.

    Charles
     
  6. Sebi

    Well-Known Member

    Sep 24, 2005
    59
    0
    A small compressor run with 0,6...0,8A, but starting current can be 6..8A!
    This current make a voltage falling on the wires. If the wiring-layout of the office is available, choose another wall-socket for lamp, nearby the mains input.
    Voltage supressors can't generate energy...
     
  7. hgmjr

    Moderator

    Jan 28, 2005
    9,030
    214
    Charles,

    Sebi is correct that the surge protectors don't have any significant energy storage so it is unlikely to solve the problem. There is no harm in trying a surge protector as you suggest. They cost next nothing and if it doesn't do the trick you can still use the surge protector elsewhere.

    I still believe that the UPS is going to the best way to eliminate the problem. You can expect the UPS to complain by beeping if the duration of the power loss is longer that it is set to ignore.

    If the light bulb you are using is incandescent, it may be worth trying one of those fluorescent equivalent bulbs to see if it will stay steady during the power sag.

    hgmjr
     
  8. Charles Flux

    Thread Starter New Member

    Aug 2, 2006
    6
    0
    Sebi, hgmjr -- Big Thank You to you both! Looks like a UPS is the way to go. Will try the suppressor, can't hurt. Though I see now that it really doesn't have much to do with what's going on. So maybe I'll just save time and get the UPS. And my computer can also benefit from it as well, as was suggested.

    Thanks again!

    Charles
     
  9. goodbyegti

    Well-Known Member

    Apr 28, 2004
    59
    1
    How about an inrush surge supressor? (NTC thermistor), they only cost about £1 but i wonder if they'd interfere with the motor starting up?

    A UPS is probably the best idea, always a nice thing to have for peace of mind anyway.
     
  10. mrmeval

    Distinguished Member

    Jun 30, 2006
    833
    2
    Can't easily suppress the inrush on a standard AC motor. There are ones which were designed to alleviate that but they are expensive.

    Things to help:
    1) Get an electrician to install a seperate drop for the refrigerator.
    2) Move the refrigerator somewhere else on another circuit.
    2) Plug the refrigerator into another outlet on another circuit.
    3) Plug the lamp into another circuit
    4) The previously mentioned UPS is more robust and you can also plug the computer into it.
     
  11. swcash

    New Member

    Sep 26, 2009
    4
    0
    This problem would be easier solved If you had stated where you live and what type of power you are using.
    That said, before spending your hard earned cash I suggest you check out the circuit in question. A loose screw terminal at the wall receptacle will have the same symptoms.
    If you have no instruments to measure the load, take the lamp and the refrigerator to another part of the house with a known good circuit and see if the lamp reacts to the refer start-up on a different circuit.
    If you are unfortunate enough to have aluminum wiring inside your home loose connections are not uncommon.

    If the problem is the starting effort of the frige there is a device sold at refrigeration supply houses called a kick start. It is a combination capacitor and start relay all in one. Very simple to install with soldering. These devices are a lifesaver when you have a refrige running off a small generator. They can be the difference between the refrige running or the refrige stalling out the generator.
    Squido W Cash
     
  12. someonesdad

    Senior Member

    Jul 7, 2009
    1,585
    141
    It sounds like the problem is the current draw of starting the compressor is causing too much of a voltage drop. I agree with swcash -- check your wiring, as a small refrigerator's compressor probably shouldn't be causing such a drop.

    If the wiring is OK, another solution would be to find a ferroresonant transformer and use it to stabilize the voltage. I have one I found on ebay and I used it for some optical measurements I made on some UV fluorescent tubes -- I first checked it with a Variac and it regulated quite well.
     
  13. 5&under=sorcery

    New Member

    Jul 4, 2010
    28
    0
    Maybe go to a different type of lamp that is less effected by the startup fluctuations? Fluorescent, led?
     
  14. Potato Pudding

    Well-Known Member

    Jun 11, 2010
    684
    92
    If it is noticeable in your desk lamp then you should be concerned about it stressing you computer power supply. Get a UPS.

    Unless your little fridge has the problem your house wiring seems suspect.

    It could be something as simple as a loose screw on the outlet wiring connection but this is potentially a sign of a fire hazard.

    I have ideas of what I would do to check for this but I can't offer them for public consumption.

    I would say you might want to have an electrician check the wiring, and for what they charge give them a real project and have another circuit and outlet added. They will basically throw the wiring check on the other outlet in for free because it should take them only 2 extra minutes unless they do find trouble.
     
  15. kyoto7

    New Member

    Oct 24, 2010
    1
    0
    That's right, I also can find the ones that are priced around 50$.......:D
     
  16. Kermit2

    AAC Fanatic!

    Feb 5, 2010
    3,795
    951
    I too would suggest a look at the wiring.

    If your house is more than 10 years old. Do this.

    Find the breaker for that room and kill the power.
    Use a lamp or radio plugged into whatever sockets these devices use to be sure power is out in these sockets.

    Using a screw driver take the cover off and then the top and bottom screw holding the socket. There should be solid copper wires with bare copper exposed on either side of the socket. Check the screws holding these wires. 99% of the time you will find they are LOOSE. If the socket is one with the push in type connection and the wires just enter a hole on the back of the socket. Cut it out and put a socket with screw terminals in its place. T

    Tightening these screws, if they are loose, should make your dimming light problem disappear. Unless this 'little' fridge of yours is not so little after all. :)
     
  17. Audioguru

    New Member

    Dec 20, 2007
    9,411
    896
    I think you have a wiring problem. The wires are too small, too long or have a poor connection.

    The lights in my home do not flicker when the huge fridge turns on.
    The lights in my office did not flicker when the huge fridge turned on.

    Are you in India or Africa where the electricity barely works?
     
  18. marshallf3

    Well-Known Member

    Jul 26, 2010
    2,358
    201
    Over time you'll appreciate having a UPS on your PC although not all will kick in with a small lowering of the line voltage. Computer power supplies are designed to take small variations in line voltage (usually down to 95V) so not all UPS devices worry too much if it's only a small variation.
     
Loading...