Phase Rotation

Depends how you look at it ...

But AFAIK, the "standard" is that if you wire a motor up with the L1, L2, L3 terminals connected to the incoming L1, L2 & L3 in that order, the motor output shaft should turn clockwise. Whether that's viewed from behind or in front of the motor is another question .

The angle measurement (whether phase or otherwise) is taken to be CCW (counter clock wise) as positive.

This is just to keep all the systems of measurement similar and avoid mistakes.

It depends upon which way one looks at it.

There is a large area in the Liverpool/UK part of the world where the phase rotation is the other way round compared to the rest of the country. Correcting it at source would cause chaos wherever 3-phase rotating machinery were used downstream of the correction.....

So the answer to the question is "no".

Do you mean, re Liverpool, what is in the diagrams in "textbooks" and "schools" or practice in the physical environment. I suspect that you mean only the latter.

I have to ask a question here, I have always thought that machine rotation was defined as drive to driven. Is that internationally accepted?

I dont think I have had time to look at what ur talking about until now. In my school days we have always used a Red , Yellow and Blue format whith a phase displacement of 120⁰ rotating in a clock wise direction. In my over 12 years as a practical rewounder, I have been useing the RYB format and the motor shaft had always moved in the clock wise direction. More so transformer crouping respects the same format of phase rotation in the clock or anti clock wise direction with Red as the refference phase.

Consider RYB in the said order as clockwise.

There is nothing wrong in using a reversed direction and adopting it as a standerd. What is importing lies in the practicle use of ur system and the direction of current flow.

U most note that motors, transformers, generators etc. uses RYB format.

Take care.

Dickson.

GA for some good common sense!

Good answer. Very similar things apply when using step motors - swap the two connections to one of the windings, and rotation reverses.

In my experience, the best way to proceed is to try it.

If there's any possibility of a hazard arising by wrong sense of rotation (damage to personnel or machinery), do your dam'dest to try it with the load disconnected (if necessary, disconnect/remove the coupling or strip & re-assemble with the key removed - if it's a splined shaft you've got problems).

If the load is connected and there may be a hazard, get everyone out of the way, & "blip" the power (with someone else having a hand hovering over the emergency stop button). You have a 50% chance of being right.

This should be done during both factory testing and on-site commissioning (unless you can check/compare the phasing when commissioning).

You did not say what your application was. It could be RF, and if so, the answer is "yes". Here is a URL that will state this convewntion for RF modulation:

http://zone.ni.com/devzone/cda/tut/p/id/1320

An excerpt from that URL:

Figure 19 A shows two sine waves that are identical in both frequency and amplitude. The only difference is that the blue wave would cross the center line before the red wave and is thus phase-shifted (is leading) a fixed amount from the red wave. B in turn, shows rotating vectors (phasors) representing these two sine waves. Since the vectors rotate in the conventional counterclockwise direction, the blue vector is also leading the red vector.

Yes. If you graph it on an x & y coordinate, the rotation is always CCW. This is how we explain leading and lagging circuits.

Surely the OP is asking if a motor is considered as running forward when seen as (say) CW from the shaft end and if CCW then is running reverse?

Prime movers are usually specified as CW or CCW as viewed from one end (the non output end if I remember correctly). I've always assumed that this comes from motor mechanics looking from the front of a car into the engine bay.

I think that its more to do with the way its represented graphically, when learning/teaching for example.

Which way the motor actually turns, or from which end you see it is irrelevant.....