motor short ?

[GregS]

I have been looking at a centrifuge, and I have a manual.
The manual shows another controller, but the motor windings are
supposed to be 4 something ohms which seems reasonable.
The unit I have has a different controller and the motor reads about .7
ohms on any leg. There are 3 WYE legs. Seems like the wrong condition,
but I can't figure how a short would appear with equal ohms.
I'm now tring to unpack the motor to see if I can detect anything.

greg

 

[Samuel M. Goldwasser]

zekfrivo@zekfrivolous.com (GregS) writes:

I have been looking at a centrifuge, and I have a manual.
The manual shows another controller, but the motor windings are
supposed to be 4 something ohms which seems reasonable.
The unit I have has a different controller and the motor reads about .7
ohms on any leg. There are 3 WYE legs. Seems like the wrong condition,
but I can't figure how a short would appear with equal ohms.
I'm now tring to unpack the motor to see if I can detect anything.

Probably different motor as well.

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[GregS]

In article <wsfknwck.fsf@seas.upenn.edu>, sam@seas.upenn.edu (Samuel M. Goldwasser) wrote:

zekfrivo@zekfrivolous.com (GregS) writes:

I have been looking at a centrifuge, and I have a manual.
The manual shows another controller, but the motor windings are
supposed to be 4 something ohms which seems reasonable.
The unit I have has a different controller and the motor reads about .7
ohms on any leg. There are 3 WYE legs. Seems like the wrong condition,
but I can't figure how a short would appear with equal ohms.
I'm now tring to unpack the motor to see if I can detect anything.

Probably different motor as well.

Well I seem to agree. I measured different winding points and its never above .7
ohms. I am going to assume its OK. I can't even find reference on the motor manufacturer.
The power drive module is really crazy. They went to a lot of trouble to build it,
and it near impossible to troubleshoot, allthough I find nothing wrong
with the 6 output power mosfets.

greg