Murex Miget,blowing 32a breaker

  1. baldy Member

    Messages:
    276
    kent uk
    Hello all.
    Anybody got any ideas why my Murex Miget is blowing a 32amp breaker in the house fusebox ?,but only on power level 6.It does it off load , no welding going on,you also get a minor blip on the bench fluo light which shares the same plug socket, just the torch pressed in, no gas plumbed in.
    Ive tried dissing the high power output to the torch , no different, dissing the output neg earth clamp from the rectifier, no different, so i guess its not that.
    I usually get three of four 3 second presses of the torch off load and then the breaker trips.Ive tried it thru a 3 pin plug in rcd and that doesnt trip, its always the 32a breaker in the house fusebox,it never blows the regular fuse in the 3 pin plug.
    I tried dissing the outputs from the main tranny before it enters the rectifier and having the rectifier inputs dissed it tripped on the first press,bizarre.So the main tranny outputs were open circuit and unloaded.
    Ive tried also dissing the 240v output from the contactor into the 6 level power selector switch, this allows the wire feed motor to spin,and the cooling fan to run and no issues at all with the welder at this point although you have no power to weld obviously.
    Im guessing its either the main transformer or the rectifier.Theres also a very minor flash at the contactor when the torch is operated on and off,again this is all off load,non welding .
    I cant work out why it would trip the 32a breaker at the first press with the rectifier dissed,but get several presses with rectifier in circuit.lost me there.i thought of back emf maybe.
    Your thoughts please gents! thanks in advance. regards Pauly
     
  2. brightspark

    brightspark Member

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    31,749
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    yarm stockton on tees
    has it always done it. are they transformer based
     
  3. baldy Member

    Messages:
    276
    kent uk
    I bought it from my Bro, who hung up his welding mask, after getting Parkinsons.Its had little use and ithought it to be a good buy.Yes its transformer based.
     
  4. brightspark

    brightspark Member

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    31,749
    Location:
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    there is the possibility that a b type 32 can trip just on plugging it in. my oilcooled welder and 3kw 110 volt transformer takes mine out nearly every time I plug in . the 13 amp plug fuse can take more starting current than a b 32 that's why they never blow .if there was a serious fault on both would go .not much options apart from trying it in someone elses socket that is fed from a rewirable db fuse or change the breaker to a c type which I don't like advising to anyone as I would test with a clamp on ammeter with inrush current just to prove whats happening
     
  5. baldy Member

    Messages:
    276
    kent uk
    I did think i might fit a blue 16a socket in the garage fed direct from a rewireable fuse type fusebox just for the welder only.out of interest whats the difference between the b and c type breaker? thanks for the replies.!
     
  6. baldy Member

    Messages:
    276
    kent uk
    Ah ive found it, it relates to the amount of trip current, type b is 3-5 times type c is 5-10 times rated current, and type d is 10-20 times .ill check it out and report back.
     
  7. brightspark

    brightspark Member

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    31,749
    Location:
    yarm stockton on tees
    a b type tripping current is 3 to 5 times current rating a c type is 5 to 10 times current rating meaning it can handle more inrush current generaly for motors and transformers
     
  8. baldy Member

    Messages:
    276
    kent uk
    Its a type B i have.Ive also found my fusebox has a few spare slots for extra an MCB, the garage is essentially on the reverse of the fusebox,so i thought about adding another mcb ,16amp type C and feeding it into a blue 16 amp socket.the socket would be about a metre from the fusebox.Im thinking a single run of 2.5mm should be ok.ill get it checked out and ask a sparky.Ill still run the welder into a service centre and get it checked i think.
     
  9. baldy Member

    Messages:
    276
    kent uk
    Also that would remove about 10 metres of cable out of the journey coming from the fusebox.
     
  10. brightspark

    brightspark Member

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    31,749
    Location:
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    a b type 32 is 160 amp a c type 16 amp is also 160 amp so no better on inrush current
     
    baldy likes this.
  11. baldy Member

    Messages:
    276
    kent uk
    Thinking of surge currents of the welder i think 4mm may be a better bet.
     
  12. baldy Member

    Messages:
    276
    kent uk
    wheres that data from?
     
  13. brightspark

    brightspark Member

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    31,749
    Location:
    yarm stockton on tees
    baldy likes this.
  14. baldy Member

    Messages:
    276
    kent uk
    if i use a type D 16amp that would be 10-20 times so 16x10-20 could be 160-320amps? That may cover the spike in the unit kicking off.A wee bit worrying, but i guess its only for a split second when it gets going.
     
  15. baldy Member

    Messages:
    276
    kent uk
    I may have an older fusebox somewhere with an old style rewirable fuse, maybe thats a better option than an mcb.Only a choice of 15 or 30amps. the 30 amps is worrying though and i think thats a non starter.
    Unless i feed it thru a rewirable 15 amp fuse into a dedicated 13amp socket and retain the 3 pin plug.
     
  16. brightspark

    brightspark Member

    Messages:
    31,749
    Location:
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    its not recommended using a d type in domestic installations your best getting a sparky in to test supply and earth loop before you start changing things
     
    baldy likes this.
  17. baldy Member

    Messages:
    276
    kent uk
    Ill get the welder checked over first,Then consult a sparky .I think the 15a old style fuse and dedicated 16amp socket could be a winner
     
    brightspark likes this.
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