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Electric Motor Configurations

AdrianWint

So I have a (new) 1.5kW motor.

The motor rating plate declares the machine as being 380V 60Hz 3 phase, 3.96A and then ' WIRED IN STAR'.

The rating plate only gives details about the star configuration - it doesn't mention delta.

Looking inside the terminal box, all 6 wire ends are brought out - three being linked to form the star point.

Removing the star point reveals that all three coils are indeed electrically separate & the opposite ends are all displaced by one position as they would need to be if one was to reconfigure this machine into delta by turning the three links through 90 deg.

My question for the learned forum - why hasn't the manufacturer given any details about the delta configuration on the plate? Indeed he has even specified 'WIRED IN STAR'.

Why would he wish to rule out the use of the delta configuration? What badness might result from me re-configuring into delta & running from 220/3/60? The windings don't care whether they are in star or delta - if I apply 380/3/60 in star or 220/3/60 in delta the winding still has the same voltage across it.

What am I missing?

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  • 0

    There is no problem so long as the winding ends are available and the sense is clear - you do need to be a bit thoughtful about the sense of winding ends, as it is possible if inept to wire a motor in delta but with one winding reversed so that it expects two phases 60 degrees apart.

    (as 120-180 is 60 ....)

    And as others have said, you keep the voltage.frequency product down below the original.
    Motors wired as star with the point of junction inaccessible  are another matter,, but not what you have here.

    Mike

  • 0 in reply to mapj1

    Thanks Mike.

    Out of curiosity, how would one winding being reversed show itself?

    I've checked for this before (by applying a small AC voltage to each winding in turn and the 'scoping the other two) but how it manifest itself if a motor with such as mistake were to be powered?

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  • 0 in reply to mapj1

    Thanks Mike.

    Out of curiosity, how would one winding being reversed show itself?

    I've checked for this before (by applying a small AC voltage to each winding in turn and the 'scoping the other two) but how it manifest itself if a motor with such as mistake were to be powered?

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