RIP DETECTION SENSOR LOOPS
The most popular belt rip detection system are induction loops/coils in combination with external transmitters and receivers.
The loops are vulcanized into the belt's top or bottom cover.
If a foreign body penetrates the belt and gets stuck in the conveyor structure, it may rip the belt.
If a sensor loop is cut by this foreign body, no signal is transferred by the loop anymore - the receiver sensor does not get a signal and shuts off the conveyor drive.
Sensor loops are sensitive parts, which may trigger off false alarm. Also if high grade iron ore like magnetite, with very strong ferromagnetic properties, is being conveyed, the rip detection system may not work properly.
Sensor loops do by far not achieve the operational lifetime of the conveyor belt.
The distance between two loops (the pitch or spacing) is usually determined by multiplying the belt speed by the time to stop the belt, divided by 2. The result will probably be between 50 to 200 m.
LASER RIP DETECTION
The laser beam hits the surface of a belt carry side before it is reflected and captured by the camera. The laser stripe is continuously analyzed by means of triangulation, to determine the width and depth of the belt’s rip or injury. The software generates a 3D image, which will depict any tearing that may have occurred. In case of a belt rip, the conveyor will be shut off automatically.
WIRE UNDER BELT
This is an old method where a wire is hanging under the belt. If a foreign body penetrates the belt and moves that wire in the running direction of the belt, a stop of the motor is induced.
It is derived from the emergency pull-wire that you find along most conveyor systems.
Indeed, the penetrating body has to emerge long enough to contact and move the string.
If the body is stuck somewhere and continuing to rip the belt, which is usually happening, the system cannot react.