Normally ON or Failsafe Brakes are spring applied, where in the slowing down activity happens because of mechanical spring pressure and the slowing down activity is released by supply of electric force. They are consistently in the brake applied or ON condition and thus the name.
Normally OFF brakes require electric force supply for slowing down to take place. They are in the brake... https://angindustries.in/electromagnetic-brakes-dealer-in-delhi.html