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Posted by Bob Minchin on April 19, 2008, 8:27 am
Please log in for more thread options Mark Rand wrote:
>
>> dm wrote:
>>>>
>>>>> Thanks
>>>>> Alas these motors are permanent star -
>>>>> Re butchering a permanent star to a delta
>>>>> Since delta uses more current would the windings necessarily take the
>>> extra
>>>>> current if I "hacked" it to a delta?
>>>>>
>>>>> Derek
>>>>>
>>>> The extra current comes because the windings are effectively in parallel
>>>> rather than in series. Same current and voltage for the windings but
>>>> SQRT 3 times the voltage and
>>>> 1/SQRT 3 times the current
>>>> for the whole motor.
>>>>
>>>>
>>>> Mark Rand
>>>> RTFM
>>> of the 4 motors on the mill
>>> one is dual voltage already (suds) one I have a cheap replacement (vertical)
>>> ,
>>> one is overspec and i'm not in rush for (horizontal arbour). The crucial one
>>> is the horizontal feed. for this I have found the star point and it "seems"
>>> straight forward to connect up as delta. Is there a way to get the physical
>>> orientation out of kilter with the electrical topology or will it all come
>>> out in the direction of rotation?
>>>
>>>
>> Not a problem. If the rotation direction is incorrect swap any two
>> supply wires over.
>>
>> Bob
>
>
> Quick rewind on that to avoid unnecessary release of magic smoke...
>
> Mark the junction box ends of the windings A1,B1, C1
>
> Using a meter, battery and bell, electric fencer and small child etc:-
> Mark the corresponding opposite (ex-starpoint) ends of the windings A2, B2, C2
>
> Now connect
> A2-B1
> B2-C1
> C2-A1
>
>
> If you accidentally connected a winding the wrong way round (say A2-B2, B1-C1)
> then the motor will draw a lot of current, generate little torque and get
> rather warm.
>
> Mark Rand
> RTFM
Yes I agree. I had assumed that the Op would have done that check. _
Always dangerous to assume!
Thanks for the addendum Mark.
Bob
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