Senile at 32...what was I writing about?

Oh, yeah!

Why would somebody want to use a delta 3-phase configuration over a star 3-phase configuration?

Drawing a total blank here...

TM

Maybe I am missing something.....but

If that is all that is available....

On more than one occasion, I have had nothing else with which to work. In such cases, especially where all I needed to do was install a small system with a couple of 3-phase motors with a small, 120 VAC control circuit, I simply installed a small transformer and used the 3-phase delta for my motors.

Is there some other bigger issue I am not seeing here?

Steve

No issues...

I've seen a few posts lately on the subject of delta/wye and star motor winding configurations. I know he voltage levels are somewhat different, but I'm not sure what the exact differences are, or why a person would choose one over the other.

Your replay makes me wonder - does this description apply to the incoming power as well as / instead of the actual motor setup?

TM

Hmmmm.......

Well, come to think of it, I alway thought in reverse of what you are.

I always thought star/delta WAS referencing the incoming power rather than the motor. I have always looked at my motors with respect to high/low voltage (ie. 460 or 230) and not really given much thought to star/delta with respect to them specifically. So long as I have the proper voltage phase to phase, see me smile.

That is certainly not to say I am right. I hope some others will join in and give a little clarification.

Steve

Equations to perhaps help:
http://www.iprocessmart.com/techsmart/3-phase_equations.htm

Help on motor control

http://www.usmotors.com/products/ProFacts/1-124.htm

Hope that helps in some way

If the type-plate of a drive says something like 690V/400V (y/d) then it is because each winding is certified for max 400V.

Connecting in d (delta) means that each coil recieves the line voltage directly.
Connecting in y (star) means that the voltage over each coil is reduced by 1.73 (the square root of 3). In that way a motor can be connected to a higher voltage than the coils are rated for.

Another reason for connecting in delta is to limit the motor torque (and thereby the motor current). The same voltage-reducting principle applies, but here the result is that the torque and current is reduced by 3. Thats why you have star-delta starters, mainly to reduce the inrush current.
A motor that is certified for 690V/400V (y/d) can be started with a star-delta starter at 400V line voltage.