[EE] 3 phase motor, wiring diagram?

[Jason White-20]

Hi everyone,

Recently I picked up a surplus 3 phase motor for a bargain.

The motor is a "MARATHON MOTORS 5KE49UN8406" [1]. It can be wired for
either 230 or 460V. In my case I will be running at 230V through a VFD. The
motor has 9 wires and its wiring diagram is nowhere to be found in person
or on the internet. Some internet sites suggest that the numbering of the
windings/terminals is pretty standard, but I am interested in getting
confirmation before I connect it to power.

What should I expect to see with a multimeter measuring resistance between
various combinations of the 9 terminals? I have to admit that I probably
more reluctant than I should be about accidentally getting it wrong. This
is because I ended up investing a bunch of time making CAD drawings and
machining custom parts to suit this particular motor before attempting to
wire and test it.

[1]
https://www.grainger.com/mobile/product/MARATHON-MOTORS-General-Purpose-Motor-4TD51


--
Jason White
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[Denny Esterline-2]

A reasonable example:
https://www.youtube.com/watch?v=DlbB8fyCiRA


-Denny


On Thu, Dec 3, 2020 at 11:04 AM Jason White <
[hidden email]> wrote:

> Hi everyone,
>
> Recently I picked up a surplus 3 phase motor for a bargain.
>
> The motor is a "MARATHON MOTORS 5KE49UN8406" [1]. It can be wired for
> either 230 or 460V. In my case I will be running at 230V through a VFD. The
> motor has 9 wires and its wiring diagram is nowhere to be found in person
> or on the internet. Some internet sites suggest that the numbering of the
> windings/terminals is pretty standard, but I am interested in getting
> confirmation before I connect it to power.
>
> What should I expect to see with a multimeter measuring resistance between
> various combinations of the 9 terminals? I have to admit that I probably
> more reluctant than I should be about accidentally getting it wrong. This
> is because I ended up investing a bunch of time making CAD drawings and
> machining custom parts to suit this particular motor before attempting to
> wire and test it.
>
> [1]
>
> https://www.grainger.com/mobile/product/MARATHON-MOTORS-General-Purpose-Motor-4TD51
>
>
> --
> Jason White
> --
> http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive
> View/change your membership options at
> http://mailman.mit.edu/mailman/listinfo/piclist
>

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[Dave Tweed]

Jason White wrote:

> Recently I picked up a surplus 3 phase motor for a bargain.
>
> The motor is a "MARATHON MOTORS 5KE49UN8406" [1]. It can be wired for
> either 230 or 460V. In my case I will be running at 230V through a VFD. The
> motor has 9 wires and its wiring diagram is nowhere to be found in person
> or on the internet. Some internet sites suggest that the numbering of the
> windings/terminals is pretty standard, but I am interested in getting
> confirmation before I connect it to power.
>
> What should I expect to see with a multimeter measuring resistance between
> various combinations of the 9 terminals? I have to admit that I probably
> more reluctant than I should be about accidentally getting it wrong. This
> is because I ended up investing a bunch of time making CAD drawings and
> machining custom parts to suit this particular motor before attempting to
> wire and test it.

[Warning: ASCII art - best viewed with a monospace font!]

I would expect that with 9 terminals, they'd be wired like this:

                      T
                     / \
                    C   C
                   C     C
                  C       C
                 /         \
                T           T

              T               T
             /                 \
            C                   C
           C                     C
          C                       C
         /                         \
        T---CCCCC---T   T---CCCCC---T

where the "T"s represent terminals, and the "C"s represent coils. For 230V
operation, you connect the coils on each phase in parallel, like this:

--------------+-------T-------+
              |      / \      |
              |     C   C     |
              |    C     C    |
              |   C       C   |
              |  /         \  |
        +-------T           T-------+
        |     |               |     |
        |     T               T     |
        |    /                 \    |
        |   C                   C   |
        |  C                     C  |
        | C                       C |
        |/                         \|
        T---CCCCC---T   T---CCCCC---T
        |           |   |           |
--------+---------------+           |
                    |               |
--------------------+---------------+

For 460V operation you'd connect them in series:

----------------------T
                     / \
                    C   C
                   C     C
                  C       C
                 /         \
              +-T           T-+
              |               |
              T               T
             /                 \
            C                   C
           C                     C
          C                       C
         /                         \
        T---CCCCC---T   T---CCCCC---T
        |           |   |           |
--------+           +---+           |
                                    |
--------------------+---------------+

The trick will be identifying which half-coils belong to the same phase
internally. It may be possible to do it by applying a low-voltage AC signal
to one half-coil at a time. I would expect that it's mate would show a
stronger response (on a voltmeter or scope) than all of the other coils.

-- Dave Tweed
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[Jason White-20]

Thanks Dave and Denny,

I really appreciate the ASCII art, it make things much clearer. I think I
can now confidentiality work out the appropriate wiring without risk of
damaging anything.

On Thursday, December 3, 2020, Dave Tweed <[hidden email]> wrote:

> Jason White wrote:
> > Recently I picked up a surplus 3 phase motor for a bargain.
> >
> > The motor is a "MARATHON MOTORS 5KE49UN8406" [1]. It can be wired for
> > either 230 or 460V. In my case I will be running at 230V through a VFD.
> The
> > motor has 9 wires and its wiring diagram is nowhere to be found in person
> > or on the internet. Some internet sites suggest that the numbering of the
> > windings/terminals is pretty standard, but I am interested in getting
> > confirmation before I connect it to power.
> >
> > What should I expect to see with a multimeter measuring resistance
> between
> > various combinations of the 9 terminals? I have to admit that I probably
> > more reluctant than I should be about accidentally getting it wrong. This
> > is because I ended up investing a bunch of time making CAD drawings and
> > machining custom parts to suit this particular motor before attempting to
> > wire and test it.
>
> [Warning: ASCII art - best viewed with a monospace font!]
>
> I would expect that with 9 terminals, they'd be wired like this:
>
>                       T
>                      / \
>                     C   C
>                    C     C
>                   C       C
>                  /         \
>                 T           T
>
>               T               T
>              /                 \
>             C                   C
>            C                     C
>           C                       C
>          /                         \
>         T---CCCCC---T   T---CCCCC---T
>
> where the "T"s represent terminals, and the "C"s represent coils. For 230V
> operation, you connect the coils on each phase in parallel, like this:
>
> --------------+-------T-------+
>               |      / \      |
>               |     C   C     |
>               |    C     C    |
>               |   C       C   |
>               |  /         \  |
>         +-------T           T-------+
>         |     |               |     |
>         |     T               T     |
>         |    /                 \    |
>         |   C                   C   |
>         |  C                     C  |
>         | C                       C |
>         |/                         \|
>         T---CCCCC---T   T---CCCCC---T
>         |           |   |           |
> --------+---------------+           |
>                     |               |
> --------------------+---------------+
>
> For 460V operation you'd connect them in series:
>
> ----------------------T
>                      / \
>                     C   C
>                    C     C
>                   C       C
>                  /         \
>               +-T           T-+
>               |               |
>               T               T
>              /                 \
>             C                   C
>            C                     C
>           C                       C
>          /                         \
>         T---CCCCC---T   T---CCCCC---T
>         |           |   |           |
> --------+           +---+           |
>                                     |
> --------------------+---------------+
>
> The trick will be identifying which half-coils belong to the same phase
> internally. It may be possible to do it by applying a low-voltage AC signal
> to one half-coil at a time. I would expect that it's mate would show a
> stronger response (on a voltmeter or scope) than all of the other coils.
>
> -- Dave Tweed
> --
> http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive
> View/change your membership options at
> http://mailman.mit.edu/mailman/listinfo/piclist
>

--
Jason White
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