You dryer has a series of safetys. If the control thermostat fails, the filter housing gets blocked with lint, or the vent gets stopped up the heat could cause a fire. The bottom cannister thermostat limit is the lowest temp one 250F, it should shut down first if it fails then the limit mounted at the top of the cannister is set to Blow at 300F When it blows that is an indication of an external vent blockage. If the problem is from within the dryer then the fuse mounted on the blower housing will blow an the dryer won't run. The fuse is rated at 350F and is tied into the door switch. That is why the wires are smaller. They don't carry the heat load. If the duct fuse blows it is the same as if you opened the door. The dryer simply quits running.