Magnetic Proximity Switch Working Principle

Magnetic proximity sensors are actuated by the presence of a permanent magnet.

Magnetic proximity switch working principle.

The presences of a magnetic field makes the thin plates flex and touch each other causing an electrical contact. Proximity sensors comprise of a permanent magnet and a pick up coil. These proximity switches have the disadvantage of being more sensitive to objects that conduct electricity than to objects that do not. A radio frequency oscillator is connected to a metal plate.

Look for sensors designed properly by a reputable manufacturer and or look for sensors specifically designed to work at higher temperatures. The solution is to make sure that the sensor is rated for the ambient temperature in the application. These magnetic proximity sensors can detect the exact position of the pig from outside the wall of the stainless steel pipe. These switches sense distances to objects by generating magnetic fields.

Their operating principle is based on a coil and oscillator that creates an electromagnetic field in the close surroundings of the sensing surface. When the plate nears an object the radio frequency changes and the frequency detector sends a signal telling the switch to open or close. Inductive proximity sensors are used for non contact detection of metallic objects. There are several operating principles used including reed switches gmr inductive variable reluctance magneto resistive or hall effect sensors.

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 through plastic wood and any non magnetisable metals. 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. 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 presence of a metallic object actuator in the operating area causes a dampening of the oscillation amplitude.