Magnetic Proximity Switch Working Principle

Inductive proximity sensors are used for non contact detection of metallic objects.

Magnetic proximity switch working principle.

These magnetic proximity sensors can detect the exact position of the pig from outside the wall of the stainless steel pipe. Working principle of magnetic proximity sensor. Their operating principle is based on the use of reed con tacts whose thin plates are hermetically sealed in a glass bulb with inert gas. Detection principle of inductive proximity sensors inductive proximity sensors detect magnetic loss due to eddy currents that are generated on a conductive surface by an external magnetic field.

The presences of a magnetic field makes the thin plates flex and touch each other causing an electrical contact. A radio frequency oscillator is connected to a metal plate. These proximity switches have the disadvantage of being more sensitive to objects that conduct electricity than to objects that do not. When the plate nears an object the radio frequency changes and the frequency detector sends a signal telling the switch to open or close.

Their operating principle is based on a coil and oscillator that creates an electromagnetic field in the close surroundings of the sensing surface. Look for sensors designed properly by a reputable manufacturer and or look for sensors specifically designed to work at higher temperatures. There are several operating principles used including reed switches gmr inductive variable reluctance magneto resistive or hall effect sensors. These switches sense distances to objects by generating magnetic fields.

An ac magnetic field is generated on the detection coil and changes in the impedance due to eddy currents generated on a metallic object are detected. Magnetic proxes are also used in clean in place cip systems at diverter panels to detect the position of the diverter pipe through the panel faceplates typically made of stainless steel. Strong magnetic fields can cause standard inductive proximity sensors to latch on. Proximity sensors comprise of a permanent magnet and a pick up coil.

The solution is to make sure that the sensor is rated for the ambient temperature in the application.