Chinese Takeaway fan

Discussion in 'Electricians' Talk' started by axialautumn, Feb 26, 2011.

  1. axialautumn

    axialautumn New Member

    Just got called out to chinese takeaway. Main extract fan not working. Its single phase and runs off a transformer with 5 speed settings. The fan is 240v and the markings have rubbed off but draws around 4-5 amps maybe around 1000w or a bit more. Its inside ducting about two ft square.

    I do houses in the main so this is new to me. The fan windings hum very loud when switched on and anything over setting 2 blows the 8amp transformer fuse within a second or so.

    There is a  cylinder that look likes it could be a large capacitor. Could it be this or is it just blown windings ? I've bypassed the transformer but it still produces the same hum and no spin.

    Your best thoughts appreciated.
  2. seneca

    seneca Screwfix Select

    You have checked that the bearings aren't seized I suppose?
  3. Mr. Handyandy

    Mr. Handyandy Screwfix Select

    Yer. WD40 up the shaft!

    Mr. HandyAndy - Really
  4. axialautumn

    axialautumn New Member

    The fan turns freely with no problems, bearings seem to be good.
  5. Mr. Handyandy

    Mr. Handyandy Screwfix Select

    Sounds like the windings are shot(melted together at some point through over-heating)especially seeing that you have bypassed the Tx and it still just hums. Don't think dodgy capacitor would blow fuse.

    I'm just guessing. Sinewave has all the proper answers :)

    Mr. HandyAndy - Really
  6. pearcy

    pearcy New Member

    just replace it im persuming its a axial fan 300/400 tops chinese will be happy
  7. Lokkars Daisy

    Lokkars Daisy New Member

    sinewave has all the right answers !!!  have you gone even softer in the head Handy ?
  8. Lectrician

    Lectrician Screwfix Select

    A blown cap would blow the fuse, but would also prevent rotation....

    Sounds like the windings are shot or the motor/shaft seised.
  9. Star-Delta

    Star-Delta Member


    The capacitor would give the motor starting and direction.
    In some cases depending on how the motor is wound the capacitor would be required to start and run the
    When the motor was sitting stalled - did you try and rotate it.
  10. sinewave

    sinewave Screwfix Select

    Your all not seeing, or ignoring the bigger picture.

    Most extracts in these type of establishments are ducted and as stated the * are not big on PPM contracts.

    You need to also be checking why this Fan is * not just how to get it going again.

    Could well be it's just age and it's had it, but it also could be that the ducting is greased up and blocked with years of gunge or the vent outlet is blocked in some way etc etc etc.

    Oh, and there's the additional liability insuarnce angle to consider when working on ducted ventillation systems which extract flamable material.

    This is why there are specialist contactors out there for the cleaning and maintenance of these things.  ;)

    Message was edited by: Screwfix Moderator
  11. Lectrician

    Lectrician Screwfix Select

    It depends on the cost if the fan. Some are in the region of £700.  A motor rewind would be around £100, a capacitor £15 ish.

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