A $50$Hp $4-$pole $460$V $60$Hz motor has the following equivalent circuit param$-$

eters:

R$1=0\mathrm{.}068$

R$2=0\mathrm{.}048$

X$1=$ X$2=0\mathrm{.}4055$

Xm $=12\mathrm{.}4$

At full load at full load and $460$V input, the slip is $0\mathrm{.}71$Hz$.$ You are powering

this motor with a VFD with an active front end and the DC link voltage set$-$

point is $750$VDC$.$ Due to the high DC link voltage, the drive can run the motor

at a maximum of $485$Vac without creating harmful harmonics.

a$.$ At $485$Vac calculate the new ID$,$ IQ$,$ IS$,$ and s$.$ Assume the torque does

not change.

b$.$ In this application, the motor will spend long periods of time running

at $15\%$ torque. What is the value of IQ$,$ Is$,$ and s at $15\%$ torque when the

motor voltage is $485$Vac?