motor winding connection: WYE VS. DELTA

[center104]

Please help me to specify the motor winding connection, WYE or Delta for 200HP, 3 phase 480V induction motor. what is the different for those two connections?

thanks

 

[davidbeach]

Why do you care? Unless you have a wye-start delta-run motor it makes no difference in the connection of the motor. NEMA dual voltage motors are almost always parallel-wye series-wye for low and high voltages while IEC dual voltage motors are almost always delta for low and wye for high. That works out because the NEMA voltages are usually in a 1:2 ratio and the IEC voltages in a 1:1.7 ratio.

 

[waross]

You will find that the standard motor voltage corresponding to a 480 volt system voltage is 460 volts.
There are 460 volt motors available but you may find that dual voltage 230:460 volt motors are more available.
There are also 230:460 voltmotors with a delta winding configuration but this is not usualy noted on the nameplate.
Both motors use the same high voltage connection but the wye uses three groups of two wires and one group of three wires for the lower voltage.
The delta uses three groups of three wires for the lower voltage.
I haven't seen a NEMA motor wound delta for years.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[center104]

Thanks

 

[tajin23]

The main difference will be the phase current, in wye connection the phase current is the same as the line, in delta phase current is square root of 3 of line current.
Using delta connection in a motor is very usefull on oscillating loads, or reciprocant machines such as compressors, line current will be more balanced, some cases you have to pay more for having the possibility of a delta connection in a motor, every phase is able to handle full voltage

 

[waross]

Thanks folks.
I was wondering about the transformer analogy. I was wondering if motor is considered as a special transformer with a delta connected secondary and either a wye or a delta primary, are there any discernable differences when the motor is operated on a bad supply.
I have never seen any difference but I thought, "If there is any difference, this is the forum to find out!"
Thanks again

Bill
--------------------
"Why not the best?"
Jimmy Carter