# power losses induction machine

I am totally lost in a question, how can be derived the friction losses of a induction machine based on this equation (It wasn’t given explication about these nor the bibliography/source of this equation and I don’t find it in the Chapman,Stevenson,Sen, Beaty among others)

$$\T_{e}=J(\frac{2}{P})\frac{d\omega_r}{dt}+T_{L}\$$
Im guessing that

• $$\T_{e}\$$ is the motor torque

• $$\J\$$ is work in Joules

• $$\\frac{2}{P}\$$ 2 divided by the nominal power

• $$\\frac{d\omega_r}{dt}\$$ the instant angular speed

• $$\T_{L}\$$ The torque of the load

But I dont have a idea how to justify the friction losses of a induction machine based on these equation

• What is the context in which you found the equation? Why do you think it can be used to derive friction losses?
– user80875
Commented May 27, 2018 at 17:45
• Because I have found it unsolved in an old notebook in the "Induction Machines" theme. Commented May 27, 2018 at 18:09
• Without some context, it is difficult to interpret. It could be used to determine the required motor rating for a load. With no load and known motor rotor inertia, it could be used in a coast-to rest test to determine the motor friction and aerodynamic drag.
– user80875
Commented May 27, 2018 at 18:36
• Thats the weird thing, I remember this one was told us just like that, with no more context. Commented May 27, 2018 at 21:20