HI ,
I am currently working with 3 phase AC servo motor and it is rated as 230VAC. I have the measurements of currents of the three phases - 1.2A, 0.8A, 0.8A respectively with load and rotating at 20 rpm. I want to calculate the torque using the relation Power = 2*pi*speed(rpm)*torque/60. for this i want to calculate the power the motor is consuming during the load.

can someone help me out in calculating the power of motor using the rated voltage and phase currents ?

 

There is a considerably more accurate and easier to use method for determining the torque fro a servo motor, which is to use the torque tables provided by the manufacturer for that specific model of motor. I learned about this in the first servomotor class I went to at the MOOG company training location.
And I offer a caution, which is that if it really is a three phase servomotor the current for each phase should be very close. Is it possible that one of those phase sources is also operating a brake release magnet?? Otherwise, all three phase currents should be similar.
OR, is it possible that what you have is a standard AC servomotor with sine and cosine phases connected like a three phase motor???

 

Check manuf. spec sheet, most offer the torque curve specifications..
Torque for most servo motors is generally maximum at zero RPM, one simple method is the spring scale method.
Is this a PM rotor 3ph version?

 

I have not come across three-phase 230 volt servo motors. Or could this be a 3-phase AC gear motor in a servo application?? That would be quite reasonable, because 20 RPM is in the realm of DC servomotors.

 

I have not come across three-phase 230 volt servo motors.

Automation Direct.

 

tons of small industrial servos use 230VAC

 

I HAVE come across many motors in packages that resemble servomotor packages, but they are just servo-style mounting AC motors.
"Just because it looks like a dduck does not mean that it IS a duck, If it does not quack like a duck.

 

Define Servo Motor????

 

I define a "servo motor" as a motor powered by servo control amplifier. That means one with a variable speed and often both speed and position feedback. Very similar motors that simply run on some fixed source of power do not fit that description, although they might even be identical physically.