Are all Deltas the same ?
Are all Deltas the same ?
(OP)
I was trying to size a delta/wye starter and all the catalogs have HP ratings for the contactors less than DOL starters. In fact they suggest to size the overloads at .58 (root 3) of the FLA rating of the motor. I understand that in delta mode of a delta/wye motor that I am supplying each phase of the motor with separate contactor pairs, and that the individual winding current is .58 of FLA. My question is what if I hardwire the delta configuration and feed the motor with a single contactor rated for FLA and sized with the actual HP of the motor. Is there a difference in the total torque/current consumption of the motor ?
Please note I understand the reason for the wye configuration to reduce starting current... I am just trying to understand the differences in delta only if any.
Please note I understand the reason for the wye configuration to reduce starting current... I am just trying to understand the differences in delta only if any.





RE: Are all Deltas the same ?
2. If I understand you correctly, you are comparing a motor controlled with a star/delta starter and a delta connected motor controlled by a DOL starter. Both configuration will have the same torque /speed/current/power characteristics in RUN condition that is when in delta mode.
RE: Are all Deltas the same ?
I was trying to size a delta/wye starter and all the catalogs have HP ratings for the contactors less than DOL starters. In fact they suggest to size the overloads at .58 (root 3) of the FLA rating of the motor. I understand that in delta mode of a delta/wye motor that I am supplying each phase of the motor with separate contactor pairs, and that the individual winding current is .58 of FLA.
///Within the delta winding only\\\
My question is what if I hardwire the delta configuration and feed the motor with a single contactor rated for FLA and sized with the actual HP of the motor. Is there a difference in the total torque/current consumption of the motor ?
///Please, clarify the difference with respect to what.\\\
Please note I understand the reason for the wye configuration to reduce starting current... I am just trying to understand the differences in delta only if any.
///The delta winding configuration has each delta winding segment voltage Ea,b=Eb,c=Ec,a connected to sqrt3 x Ea,n=Ea,b=sqrt3 x Eb,n=Eb,c=sqrt3 x Ec,n=Ec,a, respectively. E.g. if Ea,n=Eb,n=Ec,n=120VAC, then Ea,b=Eb,c=Ec,a=sqrt3 x Ea,n=sqrt3 x Eb,n=Sqrt3 x Ec,n=208VAC. The torque and power will be 3 times higher for the delta winding connection than for the wye connection. This is available in basic ac machinery textbooks, e.g. M.G. Say "Alternating Current Machines."\\\
RE: Are all Deltas the same ?
http://www.usmotors.com/products/ProFacts/1-120-7.htm
etc. for more info
RE: Are all Deltas the same ?