The most used method of measuring torque-speed
characteristics of the tree-phase induction motors (IM) is a
direct dynamometer torque measuring. The dynamometer test
method is easy to use, but it has its limitations. A big
disadvantage of the direct torque measuring is extensive
warming of stator and rotor winding during a long
measurement. This causes big change of stator and rotor
winding resistance i.e. the torque-speed characteristics is
changed. This disadvantage is very limited in the acceleration
method of measuring torque-speed characteristics.
Description of this method is in [1]. It is well known, see [2],
that when running up the motor with the flywheel at the
moment of inertia J, the whole heat energy of the winding
equals to the flywheel energy, i.e.