How do metal detectors work in food industry?

How do metal detectors work in food industry?

According to Food Quality Assurance & Inernational Food Safety  

All viking food metal detector (Ferrous Non-ferrous.Sus Detection )/

working principle as :

• electromagnetic coils are built exactly fixed in a metal detector head frame 

• The  metal detector head center coil is connected to a high-frequency radio transmitter.

• Two transmission-receiving coils sit on either side of the center coils of a metal detection 

• two outer coils are identical and the exact same distance from the center

• When two coils  of metal detector receive the same signal and produce an identical, balanced output voltage.

       when a particle of metal passes through the system,The metal detection will sense it and sent singal to control PCB 

• The high-frequency field is disturbed beneath one coil, changing the voltage and disrupting the balance.

• The output fluxes from zero, producing a signal alerting the system to the presence of metal.

• Depending on the specifics of the system, a rejection mechanism is generally activated,

• with the ideal result of removal of 100 percent of the metal and a minimum amount of salable product.