3ph motor rotation

[Janus101]

I've always used the thumb rule saying that if a 3ph motor is connected in the basic sequence, ie R-S-T/L1-L2-L3, on the motor terminals starting from the left, the motor will always rotate clockwise when look in to the shaft end.

I've bumbed in to some motors which apparently doesnt "follow" this rule. Im told that the grid supply in to the yard is in the correct sequence, and I do not have a meter to verify if this is correct.

Anyone able to confirm the thumb rule, so I can contend that the grid is wrong?

Thanks in advance.

 

[acmotorengineer]

Do not assume lead marking denotes rotation. Three lead motors are commonly not even marked.

You should check both motor and power phase sequence or bump test the motor.

There are several instruments on the market which will tell you power and motor phase sequence.

 

[busbar]

If safety or correct operation matters, it is a serious mistake to make assumptions.

Testers are readily available to determine phase sequence.

 

[Janus101]

Thanks for the replies. I appologise if I do not clearly point out my question. The question is wheter the "thumb rule" I refer to is valid or not?

The package, with the motor on it, is to be shipped away to another loaction, so the issue is just to avoid swapping of cores later on

Verifying the rotation locally and that jazz is all fine

 

[busbar]

Don't know the motor location, but in ANSI/NEMA regions, there is no "r∙o∙t" specifying direction of induction-motor rotation. thread237-40638

 

[jOmega]

NEMA ac induction motors do not follow that convention.

IEC motors do. It is imposed by the standards that govern motors.

Unfortunatley, the only place NEMA MG1 makes this is a requirement is in section 31 for Definite Purpose Inverter-Fed motors. The fact that US motor manufactures are not otherwise bound to a convention for AC Induction motors, is what prevents Inverter Motor Manufacturers from stating on the nameplate of their so called Inverter motors ... NEMA MG1-31 compliant. They can meet all of the other requirements for insulation, rise time, etc... but they don't conform to the "Direction of Rotation.... section 31.30.6

 

[electricpete]

To confirm some of what has been said. NEMA MG-1 section 2.20.2: "Terminal markings of polyphase AC machines are not related to the direction of rotation".

 

[Janus101]

Ok thanks all. Im in Europe, and I think that rules out some of the references. But thanks anyway.

 

[UKpete]

Janus101 - for Europe IEC 60034-8 specifies that the rotational direction is viewed at the "D-end" i.e. the drive end (and so does BS 4999 Pt.108). It also specifies that a motor should rotate clockwise viewed from the drive end, when the terminal markings match those of the incoming leads (i.e U to U, V to V and W to W). And of course the correct time sequence for the incoming phases should be U-V-W. If your lead markings are to the older spec, the correct sequence is Red-Yellow-Blue ("Read-Your-Books" is how I remember it).
If you see an IEC motor running anti-clockwise (viewed drive end) it is either because two of the incoming leads have been switched, or that the phase sequence of the leads isn't U-V-W due to either a wiring fault upstream or because it is operating on a reversible inverter drive.

 

[jbartos]

Suggestion: Try to obtain the motor spec sheet. Photocopies are not that expensive as they used to be 40years ago. Also, emails are capable to accept spec sheet attachments.
Here are some samples from the web:

http://www.sunonusa.com/spec/KDE0501AFB2-8(MS-OC).pdf

http://www.ketterer.de/e_images/Final_4640_engl.pdf

http://www.titancranes.com/crane_data_sheet(us).PDF

http://www.jlab.org/ccc/mail_archives/CLAS/clas_slow_control/msg00052.html

etc.

 

[Janus101]

UKpete, I think that answers/confirms my original question. Thanks.

 

[jbartos]

Suggestion: The above posted links, 1st and 3rd, need to be copied and pasted into the browser. I am sorry for any inconvenience.