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Precautions During Use

Proximity sensor Precautions During Use

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Influence of surrounding metal

  • Shielded and non-shielded proximity sensors are affected differently by surrounding metal.
    Generally, shielded types can be installed directly to or embedded in metal.
    However, if non-shielded sensors are surrounded by metal, it may cause an increase in the detection distance and problems with the reset operation.
    Therefore, each model must be installed separated from metal objects by at least the distances indicated for that model.

Reciprocal interference

  • Proximity sensors (including Capacitive Proximity Sensor) use high-frequency oscillation circuits.
    Therefore, sensors must be installed separated from each other by at least the indicated distances when multiple proximity sensors are installed side-by-side or facing each other.
    To prevent such interference, we offer also sensors with a different frequency (B type).
    Installation distances between sensors may be decreased by using different frequency types in combination with your sensors.
    (Note however that there are no different frequency types for Capacitive Proximity Sensor.)

About detection target size, material and coating (do not apply to electrostatic-capacity sensors)

  • Detection distances have been set for each model using a standard detection target of a specific size.
    The detection distances may decrease with smaller detection targets.
  • Generally, standard detection targets are iron plates (magnetic metal) of 1 mm in thickness.
    The detection distance may decrease by 20% to 80% in case of non-magnetic metals.
    Since the distance depends on the material, it is recommended to verify it in advance.
    However, note that although detection distances similar to those of magnetic metal may be obtained with foils (0.01 mm or less in thickness) due to skin effect from eddy current, ultra-thin targets with no conductivity, such as deposited films, cannot be detected."
  • If the detection target is coated, the detection distance may decrease depending on the coating type.
    Therefore, it is recommended to verify the distance in advance.
    Note that the detection distance will not vary significantly when the metal surface is painted with insulation material.

About the operating environment

  • Avoid using the sensors outdoor, in locations exposed to direct sunlight, or in locations where the temperature may vary rapidly and repeatedly.
    Otherwise, the internal parts and the case may deteriorate.
  • Avoid using the sensors in locations where chemical, organic solvents, or other such materials may splatter.
  • If the sensor is installed near devices generating large surges, such as motors, welding machines or solenoids, install a surge absorber to the surge generating device.
  • When using a switched-mode power supply, always connect the FG terminal to the ground to prevent generation of harmonics.
  • Proximity sensors (including Capacitive Proximity Sensor) use high-frequency oscillation circuits.
    Therefore, the sensor may malfunction if high-frequency devices (welding machines, inverter-fed motors, broadcasting stations) are used near the sensor installation location.
    Always connect installed and surrounding metal objects to the ground.

About the wiring

  • Always check that the wiring is correct before turning on the system as incorrect wiring may damage internal circuits.
  • Use large-diameter cables when extending the cord to minimize voltage drop effects.
    Note that distortion may appear in the output waveform when using an extension cable depending on the line capacity.
  • If the cables are installed parallel to high-voltage lines or power lines, malfunction or damage may result from induction noise.
    Therefore, separate the cables or install them into an independent metal raceway.

About the load used

  • A transistor is used for the sensor output.
    Therefore, the transistor may deteriorate or be damaged if an inductive load generating large inrush current, such as a lamp or a motor, is switched.In such cases, use a relay or similar device.

About static electricity resistance of pass-through proximity sensors

  • Install the system so that the pachinko balls always come from the surface showing "IN". The circuit is protected because the pachinko balls rub plastic or other surrounding materials and discharge the accumulated static electricity to the static electricity shield plate when they pass through the sensor.

貫通タイプ近接センサの耐静電気について

About power supply of Capacitive Proximity Sensor

(1) When power is supplied by a battery
  • Connect directly, or via a 1000 pF capacitor, the GND side (0 V) of the sensor power supply to the earth or to a large metal frame. Connect it fully without any poor contact.

静電容量形近接センサの電源について

(2) When the coupling capacitance is small between the primary and the secondary sides of the sensor power supply
  • When using a DC to DC converter, connect directly, or via a 1000 pF capacitor, the GND side (0 V) of the sensor power supply to the earth or to a large metal frame. Connect it fully without any poor contact.
    If the above connection is not possible, connect it to the GND side of the primary-side DC power supply.

    静電容量形センサ電源の1次-2次間の結合容量が小さな場合

  • When using an AC to DC converter, or when the GND side (0 V) of the electrostatic-capacity sensor power supply cannot be connected to the earth or a large metal frame as explained above, connect it to the primary AC power supply side via a 1000 pF capacitor. Connect it fully without any poor contact.

    静電容量形センサ電源の1次-2次間の結合容量が小さな場合


    *Use a capacitor with sufficient withstand voltage.
  • If using a power supply with lots of common-mode noise, connect directly, or via a 1000 pF capacitor, the 0 V line of the electrostatic-capacity sensor to the metal frame where the sensor is installed.
    Connect it fully without any poor contact.

About the Capacitive Proximity Sensor installation

  • The detection distance varies depending on the target conductivity, permittivity, and volume.
    Therefore, check the detection distance in advance using the appropriate target, and set the distance taking into account an error margin.
    If one or several targets with small permittivity are placed or stacked on the detection surface, the reset operation may not work properly due to the quantity target objects.
    It is recommended to check that such problem does not occur before using the sensor.
  • Note that the reset operation may not work properly if water adheres to the detection surface, or if condensation or frost is generated due to change in the temperature.

 

 

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