terminology for describing direction of rotation 1

[electricpete]

I am buying a TEFC motor and I want to make sure I specify right direction of rotation (in case there is a directional fan...I'm not worried about swapping two leads if needed) in a concise and unambiguous manner.

The best I can come up with:
CCW when viewed from...
[*]motor ODE-to-DE
[*]or motor front-to-back,
[*]or motor-to-pump
[*]or standing at outboard end of motor

Does any of these sound reasonable or better suggestions?

I recall there is very precise terminology for describing horiziontal motor term box location (F1 and F2) but I don't recall NEMA MG1 giving me any clues on standard terminology to define direction of rotation on a horizontal motor.

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[Skogsgurra]

Europe standardized this around 1960. The rule now is: Look at the shaft end from outside the motor (outboard). If it rotates clockwise, then the rotation is positive (yes, contrary to positive rotation in a co-ordinate system).

Please note that the use of Sun as a reference was abandoned when companies started exporting machines to counttrie sout of the Equator.



Gunnar Englund

http://www.gke.org

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[electricpete]

cw "From shaft end" is pretty unambiguous. Not standard but probably works best.

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[electricpete]

Your pulling my leg about the equator thought, aren't you?

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[Skogsgurra]

No. It was a real problem. ASEA (now ABB) is a Swedish company and they used "Solar direction" to describe rotation. After a few problems with Australia and South America, they changed that to CW and CCW. I worked with them in Västerås at that time.

Gunnar Englund

http://www.gke.org

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[dpc]

I've normally seen rotation specified as CW or CCW from Driven End (DE) or Non-driven End (NDE). Sometimes Non-driven end is referred to as Opposite Drive End (ODE).

But I'm left-handed, so YMMV.

David Castor

http://www.cvoes.com

 

[electricpete]

Gunnar - I can't quite fathom using the sun as a reference for motor rotation direction. But I'll take your word for it.

dpc - CCW from O.D.E. should be unambiguous as well.

I guess I just made my original descriptions needlessly complicated by interjecting the "to" (ODE - to - DE). There are lots of good ways to say it if I get rid of the to.

By the way, interesting twist to call it "driven end" and "opposite driven end"... I think that is more descriptive than the usual "drive end" and "opposite drive end" which can confuse vibration people that are used to conventions like "driver to driven" for describing orientation from which rotation is viewed.


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[Skogsgurra]

Yes, it is Drive (or driving) End.

Gunnar Englund

http://www.gke.org

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[electricpete]

Now curiosity is getting the better of me. How did they use the sun as reference for direction of rotation?

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[Skogsgurra]

Same way as you deal in poker. Thinking that you look at the table and the watch when it is put on the table. That is still called "Solar Direction" (or "medsols") in some places. Like Sweden.

So, in the northern hemisphere, "Solar Direction" was the same as CW while it wasn't in the southern hemispere.

Gunnar Englund

http://www.gke.org

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[Skogsgurra]

Found this for you. Note the term "sunwise".

http://en.wikipedia.org/wiki/Clockwise

Gunnar Englund

http://www.gke.org

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