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Dolphintek (Aeronautics) (OP)
31 Dec 02 16:50
If one looks at an electric motor the rotation can be CW or CCW depending upon which end of the motor one is viewing from. Dumb question but I have forgotten how to determine CCW or CW so as to order a replacement.  Having a senior moment I suppose! Thanks! Happy New Year!
jbartos (Electrical)
31 Dec 02 19:13
Suggestion: Some better manufactured motors around have an arrow defining CW or CCW direction of the motor rotation. This eliminates any ambiguity.
Happy New Year to you too and to others.
dpc (Electrical)
31 Dec 02 19:22
For NEMA motors, I believe the rotation is specified as CW or CCW looking from **the opposite drive end**.  

I generally call it out explicitly just to make sure.  

This is not as hard to remember as the left-hand vs right-hand door swing!

electricpete (Electrical)
31 Dec 02 19:24
NEMA MG-1-1998 Rev 2 Para 14.6 - Direction of Rotation -

talks about the fact that the standard direction for dc motors single phase ac motors is counterclockwise, when viewed from the end opposite the drive end.  (I call that the outboard end.... the non-shaft end).

So it sounds like if you say nothing, that's what you get. If you want different then tell 'em.

Either way it wouldn't hurt to tell 'em which end you're looking at when you say CW or CCW.

You may already be aware that the direction of 3-phase motors is easily reversed by rolling the leads.  Also there have been some threads by people talking about possible reversing the smaller motors too.... a little more complicated.
jbartos (Electrical)
31 Dec 02 21:28
Suggestion: To rely on the motor rotation reversion, one may be prepared for some additional expense, namely, the fan cooling should be adjusted. This is not possible in some cases.
Helpful Member!  jlhmaint (Electrical)
1 Jan 03 12:43
I have allways approached it from the shaft end but you just have to check with suppliers because as others have said it depends which end they are looking at. i found this on another web page,
Rotation is obviously an extremely important motor attribute.  While many motors are easily reversible (for example, most three phase motors), others are not.  For non-reversible motors, you must be very careful to check, and double check that the correct rotation is being specified.   Unfortunately, the vendors don't make it easy on any of us, since the specifications of "CW", and "CCW" of course depend on the direction you are viewing the motor; i.e. are you viewing the motor by looking at the shaft end or the opposite end.  Some vendors use the shaft end as the reference others use the opposite end.

The following table, lists some common rotation specifications which do not depend on the viewing reference.
 Label Descripition
CCW / LE or CCWLE Counter clockwise from the lead end
 
CCWSE Counter clockwise from the shaft end

CW Rotation Only Shaft can only rotate in a clockwise position

CW / OLE Clockwise opposite lead end

CWLE Clockwise from the lead end

CWSE Clockwise from the shaft end

Double Shaft / CCWLE Spins counter clockwise on a double shaft from the lead end

Double Shaft / CWSE Spins clockwise on a double shaft from the shaft end

CW / CCW or Reversible Clockwise or counterclockwise
 
ECW Either clockwise or counterclockwise, connected for clockwise rotation at factory

ECCW Either clockwise or counterclockwise, connected for counterclockwise rotation at factory
 
Reversing Plug Switching the reversing plug changes the rotation of the shaft

CW or CCW The real meaning of these labels is dependent on the manufacturer.  
 

UKpete (Electrical)
2 Jan 03 7:39
Just to catch out the unwary - unlike NEMA, IEC 60034-8 specifies that the rotation direction is viewed at the "D-end" i.e. the drive end (and so does BS 4999 Pt.108).  

As IEC specify that a motor should rotate clockwise viewed from the drive end, the end result is that it is equivalent to NEMA which is anti-clockwise viewed from the non-drive end.  

As many manufacturers supply both NEMA and IEC motors, it is sensible when specifying direction to also specify the end it's viewed from.

upen1 (Electrical)
2 Jan 03 15:10
step 1) Check whether motor has non reverse ratchet or not
        if yes then motor will run only in one direction.
Step 2) Check lableling of the main leads of motor usually
        motor manufacture phased out leads with the       
        incomming phases.
Step 3) If load is pump, check in which direction you get
        desired flow rate. In order to check fan whether
        it is directional or bi directional, check in
        which direction you get air output from enclosure.
Step 4) Check the load in case it indicate direction of
        rotation because in pump application sometimes
        arrow indicated on pumps too.  
 

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