Magnetic proximity sensors These are actuated by the presence of permanent magnets. Operating principle : reed contacts Reed Contacts (two low reluctance feromagnetic reeds enclosed in glass tubes containing inert gas) Has a built in oscillator (LC).

Magnetic proximity sensors

Magnetic proximity sensors Switching blade continually interrupts the air flow of an impending signal. As magnetic field approaches the switching blade is attracted and releases the air flow, creates a signal at output.

Reed Sensors Perpendicular magnet travel

Reed SensorsParallel Magnet Travel

Reed Sensors Nose to Nose activation

Reed Sensors Rotational magnet travel

Magnetic Proximity Sensors Biasing Shielding

Outputs

Reed Contact Protections life depends on characteristics of load. Life span of magnetic sensor at low values of V & I depend on mechanical characteristic of contact while for higher values the operating.

AdvantagesAdvantages compared to mechanical Contacts are well protected against dust, oxidization and corrosion due to the hermetic glass bulb and inert gas. Special surface treatment of contacts assures long contact life. Maintenance free Easy Operation Reduced size

Pneumatic proximity sensors Presence or absence of objects is detected by means by contact less sensing with air jets. Distance range: 0 to 100mm Types: Back pressure sensors Reflex sensors Air Barriers

Back Pressure Sensors

Reflex sensors

Air Barriers

Advantages Operational safety in dusty environment Safety with high ambient temperature. Used in areas of explosion hazards. Insensitive to magnetic influences and sound waves. Reliable in extreme ambient brightness for sensing of light transparent objects, where optical proximity sensors may not be suitable.

Light energy into electrical signal Cabels of mechanical component

Fiber cables of two types: Glass Fiber Plastic Fiber

Glass Fiber cable Vs Plastic Fiber Cable. Total Internal Reflection. (TIR)

Sensing Modes and Assemblies Sensing Modes: Diffuse Thru- Beam Retro reflective.

Assemblies : Individual : Thru-beamBifurcated :Diffuse ,Retro reflective.

Advantages Disadvantages