What will be the suitable sensor that can detect a cut in the conveyor belt ?
A limit switch can be installed below or above the conveyor by touching the belt. During normal position, the limit switch will be activated and the same will return back to OFF when the conveyor gets cut. Multiple limit switches may be required to connect in series according to the length of the conveyor.
You can also use proximity sensors and photo electric sensors for this application which can be mounted without touching the conveyor but auxiliary supply will be required for functioning of these sensors.
You may down load the catalog from below link; the details of proximity sensor and photo electric sensors are available in the catalog.