2.3.2 Mechanical limit rating
When the power is increased in duty types S2, S3, and S6 the mechanical limit
rating Pmech must be noted. Standards state: "It must be possible to overload
multiphase induction motors regardless of their duty type and design for
15 seconds at the rated voltage and input frequency up to 1.6 times the rated
torque." Catalog data however are subject to tolerances up to -10% so that the
pull-out torque MK should be higher by a factor of ≤ 1.76 with respect to the
new increased torque Mmax. Therefore the mechanical limit rating can be
defined as follows with regard to catalog data: