Hi All,

I need help to calculate the rotor temperature of the 85 MVA generator by means of excitation voltage and excitation current. Any can suggest the formula to implement in the logics.

 

CTM... the calculation is extremely complicated.

If you need a relatively accurate Temperature Value there is a much simpler approach. Interested?

Regards,
Phil Corso

 

Dear Mr. Corso,

Please share. it will be helpful for me.
Thank You

Regards
CTM

 

CTM… using my GiFiES (pronounced "Jiffys") technique:

Given:
Excitation Volts, Vx @ Alternator Load(x).
Excitation Amps, Ax @ " "
Excitation Power, Px @ " "
Rotor Resistance, Rx @ " "
Rotor Resistance, Ro @ Temperature To.

Find:
Operating Temp, Tx, associated with Alternator Load(x)!

Equations:
a) Vx = Excitation, Volts.
b) Ax = Excitation Current, Amps.
c) Px = Vx*Ax or (Vx)^2/Rx, Watts
d) Solving for Rx yields, (Vx)^2/Px
e) Tx = [(Rx/Ro)*(Kcu+To)]–Kcu, where Ku is a material-constant; 234.5 for copper!
f) Tx = [(Vx)^2/(Px*Ro)]*[234.5+To]-­234.5

Solution:
Consider a large 2-pole machine where: To = 40ᵒ C; Ro=0.096 Ω; Vx=200V; Px=300kW. Then Tx=[(200^2)/(300,000*0.096)]*(234.5+40)-234.5, or about 147ᵒ C.

CTM151282... Caveat:
The above presumes no-load excitation-current is zero! In fact, it could be higher than 30% of the machines nominal rating. Thus, if you are using the machine’s design Ro, determined for a specific temperature, then a correction must be made covering the no-load case!

Regards,
Phil

 

Correction to my earlier post:

e) Tx = [(Rx/Ro)*(Kcu+To)] –- Kcu, where

Phil

 

Thank you so much Mr. Phil Corso

Regards
CTM

> Correction to my earlier post:

> e) Tx = [(Rx/Ro)*(Kcu+To)] –- Kcu,