Jurijs,
FTM fault is a feature used by FTM to automatically shut down PWM outputs when the fault pins become asserted (set or cleared).
This feature is important in control applications where if a fault occurs (over current, over temperature, etc.) the outputs can be automatically and quickly disabled to avoid damaging the hardware or other catastrophic events.
For specific details on how it works and how to configure faults (there are many modes), you can consult the ref manual:
http://cache.freescale.com/files/32bit/doc/ref_manual/K40P100M100SF2V2RM.pdf?fpsp=1
Page: 914, or the fault control section of the FTM chapter of the specific Kinetis device you are using.
