Proximon Controls Pvt. Ltd.

Proximon Controls Pvt. Ltd.
Proximon Controls Pvt. Ltd

Inductive Proximity Sensors Proximon Controls Pvt. Ltd

  1. Proximon Controls Pvt. Ltd

    Inductive Proximity Sensors

    Inductive Proximity Sensors are used for non-contact metal sensing. Being contactless sensors these can be used for position sensing, speed measurement, counting, etc. They can be used in extreme conditions, such as oily, dusty, corrosive environment. Their application ranges from automobile industries to steel industries, from CNC/NC machines to material handling equipments, process automation, conveyor systems, packaging machines.

  2. Operating Principle

    An inductive proximity switch is designed to detect, and react to any metal object which moves into the operating zone situated immediately in front of its sensing face.

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    This sensing face comprises a coil, the winding of which is fed from an oscillator, the whole creating an alternating magnetic field in front of the coil.

    Whenever a metal object moves into this field, the resulting induced currents form an additional load, and the oscillations cease.


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  3. Sensing Distance

    The distance between the target and the active face at which the sensor switches.

  4. Nominal Sensing Distance (Sn) :

    Proximon Controls Pvt. Ltd The operating distance for which the switch is designed. This value should only be taken as a guide, since no manufacturing tolerances, or changes in voltage or temperature, etc., during operation are taken into account.

  5. Usable Sensing Distance (S)

    The true sensing distance, derived by testing with a standard metal target during extremes of supply and temperature variations. Usually found as 0.80 Sn < S < 1.20 Sn.

  6. Operating Sensing Distances

    Is the distance at which a proximity sensor senses the target reliably. It is between 0 % and 80 % of the nominal sensing range.

  7. Operating Voltage

    Voltage range in which the proximity sensor can function reliably.

  8. Ripple

    Ripple is the alternating voltage superimposed on the DC voltage (Peak - Peak) in %. For the operation of DC voltage switches, a filtered DC voltage with a ripple of 10 % maximum is required.

  9. Voltage Drop

    The maximum voltage drop across a conducting sensor.
  10. No-Load Current

    Is the consumption of current of a sensor in its non-active state.
  11. Maximum Load Current

    Is the maximum current which may be drawn continuously through the sensor in active state. Usually it is less than or equal to 60 % for reliable working of the sensor.
  12. Normally Open Output (N/O)

    This type of output will switch on the load whenever a target comes within the operating zone. (Normal condition is when no target is present).
  13. Normally Closed Output (N/C)

    This type of output will switch off the load whenever a target comes within the operating zone. (Normal Condition is when no target is present).
  14. Changeover Output (N/O + N/C)

    This type of output will switch two separate loads whenever a target comes within the operating zone. 1 Load will be switched on and the other will be switched off whenever a target comes within the operating zone. (Normal condition is when no target is present).
  15. N. B.

    DC switches employ a transistor as the output switching device. AC switches employ a thyristor as the output switching device.
  16. NPN Output

    Proximon Controls Pvt. Ltd Proximity sensor with NPN output switch the negative potential to the load. It is also described as negative-switching or current-sinking.
  17. PNP Output

    Proximon Controls Pvt. Ltd Proximity sensors with PNP output switch the positive potential to the load. It is also described as positive-switching or current-sourcing.
  18. Repeatability

    The repeat accuracy of a sensor to detect an object at the same distance from the active sensing face. It is expressed in mm or in percentage of the sensing distance.
  19. Reverse Polarity Protection

    Proximity sensors which are protected against reversal in voltage polarity.
  20. Short Circuit Protection

    Proximity sensor protected from damage when a shorted condition exists for an indefinite or defined period of time.
  21. Switching Frequency

    The maximum number of times per second the sensor can change its state (on and off) usually expressed in hertz (HZ).
  22. Temperature Drift

    Specification used to indicate the change in switching point caused by temperature variations within a specified ambient temperature range. Expressed as a percentage of the sensing distance.
  23. Hysterisis

    Proximon Controls Pvt. Ltd The difference between the operate (Switch-on) and the release (Switch-off) is called hysterisis. This helps the sensor to avoid chattering i.e. accidental switch cycling, when subject to vibration, electrical noise, or temperature drift.
  24. Standard Target

    The active face of the proximity switch is the surface where a high-frequency Electro-Magnetic field emerges (However, no direct magnetic field occurs). The target consists of steel, 1 mm thick, square form with side lengths equal to the diameter of the sensing surface circle.
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  25. Target Correction Factors

    To determine the sensing distance for materials other than the standard mild steel, a correction factor is used. Multiply the listed nominal sensing distance for that material. The correction factors listed below can be used as a general guideline.

     

    Mild Steel Approx. 1.0 x Nominal Sensing Distance
    Stainless Steel Approx. 0.9 x Nominal Sensing Distance
    Brass Approx. 0.5 x Nominal Sensing Distance
    Aluminium Approx. 0.45 x Nominal Sensing Distance
    Copper Approx. 0.4 x Nominal Sensing Distance
  26. The size and shape of the target may also affect the sensing distance. The following should be used as a general guideline when correcting for the size and shape of a target :
    1. Flat targets are preferable.
    2. Rounded targets may reduce the sensing distance.
    3. Nonferrous materials usually reduce the sensing distance.
    4. Targets smaller than the sensing face typically reduce the sensing distance.
    5. Targets larger than sensing face may increase the sensing distance.
    6. Foils may increase the sensing distance
  27. Flush Installation :

    Proximon Controls Pvt. Ltd A proximity sensor can be mounted in metal upto the active surface. No side sensing occures in these sensors. However, the sensing distance is less in these sensors compared to non-flush sensors.
  28. Non-Flush Installation

    Proximon Controls Pvt. Ltd A proximity sensor must be installed in such a way that metal free-zone is maintained (To avoid side sensing). Sensors for non-flush mounting have an extended sensing distance compared to sensors for flush mounting.