Low voltage motors - star (wye) or delta?
Low voltage motors - star (wye) or delta?
(OP)
Hello all,
I have been looking at a specification for low voltage (LV)3-phase ac induction motors. It specifies that all LV motors shall be connected in star and not delta.
I can understand the reason for connecting HV machines in star (economics of providing kV/mm for the insulation systems etc.) but it is less clear to me for LV motors.
I would appreciate any thoughts.
Thanks.
P
I have been looking at a specification for low voltage (LV)3-phase ac induction motors. It specifies that all LV motors shall be connected in star and not delta.
I can understand the reason for connecting HV machines in star (economics of providing kV/mm for the insulation systems etc.) but it is less clear to me for LV motors.
I would appreciate any thoughts.
Thanks.
P





RE: Low voltage motors - star (wye) or delta?
Based on speculation—for smaller motors, wye windings with fatter magnet wire may reduce manufacturing costs, and better handle starting/overload thermal/mechanical conditions.
RE: Low voltage motors - star (wye) or delta?
In LV motors, smaller ones tend to be star. European practice (Siemens, ABB, Loher) seems to be that larger motors bring out both ends of the windings and allow connection in delta for 380V-415V operation and star for 690V operation.
RE: Low voltage motors - star (wye) or delta?
RE: Low voltage motors - star (wye) or delta?
In NAmerica we normally bring 3 leads to the motor JB and the internal connection may be Star or Delta.There are motors that have up to 9 leads out to the JB with the other 3 leads hooked up Star internal.These were fairly common in Europe before the use of VFDs became in vogue.If the motor has dual voltages,dual speeds or a combination there of, it will require more than 3 leads out.
I don't know of any rule that requires a particular motor that due to its size or voltage rating, has to be Star or Delta.Internal characteristics and design will determine the connection.
GusD