Re: 240v 3 phase in 415v 3 phase motor

Mark Rand wrote:
On Fri, 18 Apr 2008 20:03:28 GMT, Bob Minchin <nospam@xxxxxxxxxxxxxxxx> wrote:

dm wrote:
"Mark Rand" <randm@xxxxxxxxxxxxxxxxx> wrote in message
news:s0ve045761f16mn7mqekpdv9jehisl3dpm@xxxxxxxxxx
On Thu, 17 Apr 2008 17:17:13 +0100, "dm" <derek@xxxxxx> 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
.

Relevant Pages

  • Re: 240v 3 phase in 415v 3 phase motor
    ... 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 ... The extra current comes because the windings are effectively in parallel ...
    (uk.rec.models.engineering)
  • Re: 240v 3 phase in 415v 3 phase motor
    ... 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 ... The extra current comes because the windings are effectively in parallel ...
    (uk.rec.models.engineering)
  • Re: 240v 3 phase in 415v 3 phase motor
    ... 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 ... The extra current comes because the windings are effectively in parallel ...
    (uk.rec.models.engineering)
  • Re: 240v 3 phase in 415v 3 phase motor
    ... 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 ...
    (uk.rec.models.engineering)
  • Re: Induction motor winding questions (clarification)
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