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Sensors. May 25, 2013. Classification of Sensors. Sensors are classified as either : Contact type Non-contact type (proximity sensors) Proximity sensors being the more commonly used sensor. Classification of Sensors. Sensors are further categorized as either : Binary Analogue.
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Sensors • May 25, 2013
Classification of Sensors • Sensors are classified as either : • Contact type • Non-contact type (proximity sensors) • Proximity sensors being the more commonly used sensor.
Classification of Sensors • Sensors are further categorized as either : • Binary • Analogue. • Binary sensors convert a physical quantity into a binary signal which means it has two switching states. The most common being an electrical signal ON or OFF.
Limit Switches Limit switches are considered to be contact sensors, as it needs to be actuated to give a signal output
Reed Switches Most Widely Known and Used as Cylinder Switches
Glass Tube filled with nitrogen Reed contacts LED indicator
Sensor Object Sn Sensor Switching Distance Sn = Switching Distance
Sensor Hysteresis Sensor Object h Sn Sn = Switching Distance h = Hysteresis
Inductive Proximity Sensors High Frequency magnetic field (300 to 800 kHz) Active Surface Resonant circuit coil LED indicator Connection cable
Target Sensor Oscillation Amplitude Sensor output signal ON OFF
Target Sensor Oscillation Amplitude Sensor output signal ON OFF
Target Sensor Oscillation Amplitude Sensor output signal ON OFF
Target Absorbtion of energy Sensor Oscillation Amplitude Sensor output signal ON OFF
Target Sensor Oscillation Amplitude Sensor output signal ON OFF
Target Sensor Oscillation Amplitude Sensor output signal ON OFF
Target Sensor Oscillation Amplitude Sensor output signal ON OFF
Target Sensor Oscillation Amplitude Sensor output signal ON OFF
Target Sensor Oscillation Amplitude Sensor output signal ON OFF
Target Sensor Oscillation Amplitude Sensor output signal ON OFF
Inductive Proximity Sensors • The bigger the coil, the greater the active switching gap. • Inductive sensors can only detect metals. • Different switching distances for different metals
Inductive Proximity Sensors Material Reduction Factor Mild Steel 1.0 Chrome Nickel 0.70 ~ 0.90 Brass 0.35 ~ 0.50 Aluminum 0.35 ~ 0.50 Copper 0.25 ~ 0.40
Inductive Proximity Sensors • Inductive sensors detect metals and operate quickly, reliably and tirelessly. They are used to: • Count • Identify • Detect • Switch • Control • Check • Distinguish • Sort • Position
Inductive Proximity Sensors Sensing a Cam Controller
Capacitive Proximity Sensors Sensor is looking for a change in capacitance in the active field Electrostatic field Active surface Active electrode Earth electrode LED indicator Adjusting screw Connection cable
Capacitive Proximity Sensors • Almost similar to the inductive sensor. • Able to detect most materials. • Switching distance adjustable. • Able to detect fluid level through the wall of a bottle.
Sensor is adjusted so that it does not ‘see’ the wall of the vessel.