EuroSpec Proximity Sensors
are inductive sensors with quick response, long operation life,
reliable action, high anti-interference, anti-shock, water-proof
ability. It can be applied in metal detection, counting, RPM measuring
in mechanical devices, chemical, paper manufacturing, light industry
and etc. We have a great variety of models: M8, M12, M18, M30,
Rectangle, Pancacke and Non-mettalic; Embeddable and Not Embeddable;
NO, NC and NO+NC; DC or AC; 2, 3 or 4 wires; cable, M8 or M12
connector version; PNP or NPN. It is the best selling sensing
technology worldwide!!!
Working Principle - Inductive Sensors
The sensor is made up of four components: 1.coil, 2.oscillator
circuit, detection circuit and 4.output circuit.
The coil is located within the sensor’s face. The inductive
sensor’s oscillator circuit then generates a fluctuating
current through the copper wire and induces a magnetic field in
the coil. This field is directed and shaped byt the ferrite core.
The core ensures that the field is present only at its front end,
or face. The magnetic field that extends from the inductive proximity
sensor’s face induces Eddy currents in the target detectable
object. The Eddy currents in the detectable objects themselves
magnetically push back and dampen the inductive sensors own oscillation
field. The field collapses due to losses in energy caused by Eddy
current and it is detected by the evaluation circuit which then
changes the state of the output circuit.
Applications
Inductive sensors have wide uses in many applications mainly when
detecting distance is one inch or less, the application is for
metal sensing and in harsh environment (dusty and dirty). It can
be used in the presence of oils, powders, liquids and vibrations
which do hot have any effect on their secure functioning. Example
of some applications: textile machines, transport systems, packaging
equipment, machine tools, transfer lines, automobile industry
and any other application where solutions for automation are required.
Embeddable (Shielded, Flush mountable) or Not Embeddable
(ushielded, Non-flush mountable)
As the electromagnetic sensing field shape is determined by the
ferrite core, in the not embeddable model the electromagnetic
field radiates laterelly and axially, making the sensing area
relatively wide, extending beyound the sensor's side. The lateral
radiation prevents embeddable mounting in metal. The electromagnetic
field will induce Eddy currents int the metal base causing false
reading.
The embeddable model will sense only metal directly in front of
the active face and because of that they have a narrower sensing
area and a shorter sensing range, about 40% shorter than a not
embeddable model.
Detection Capability
If you examine an inductive proximity sensor’s specification
sheet, you can typically find technical information that refers
to the “standard detectable object.” This object is
usually a square made of an iron (ferrous) material with a 1mm
thickness and a side equal to the diameter of the rated proximity
sensor’s face.
Other materials, such as stainless steel, brass, aluminum, and
copper, have different specification ratings.
For example, to calculate the sensing distance of an inductive
proximity sensor when it is detecting a stainless steel material,
multiply the standard sensing distances by a reduction factor
of 0.8. Other multipliers are: 0.5 for brass, 0.4 for aluminum,
and 0.3 for copper.
Also, the detecting distance of the inductive proximity sensor
changes with the shape and size of the detectable object.
Used under proper circumstances, one can expect the life of the
inductive proximity sensor to be about 100,000 h
Mounting and Set Up
Considering the costs of labor, a sensor’s ease of setup
and mounting becomes an important issue for machine designers.
70% plus of all inductive proximity sensors sold worldwide are
of the cylindrical housing variety. These housings are specified
by their diameter and thread pitch.
For example, a popular inductive proximity is the nickel-plated
brass barrel specified at M12x1. This means that the sensor has
a 12 millimeter (mm) cylindrical housing (and roughly, a 12mm
sensing face) that is threaded at a 1mm pitch.
The 1mm pitch means that if one adjusts the M12 cylindrical inductive
proximity sensor in a full rotation, the sensor will move laterally
by 1mm. Armed with this information, your installation technician
can quickly and effectively setup a new or replacement inductive
proximity sensor.
Environmental Surroundings
Extremes temperatures can reduce their operating life, and could
cause premature failure. Higher temperature extremes can cause
the inductive proximity sensors to become more sensitive while
extreme cold temperatures lower the sensor’s resistance
to shock. Also, the semiconductors contained within inductive
proximity sensors may begin to behave erratically under extreme
temperatures either producing an output when not expected or not
responding.
Not embeddable inductive proximity sensors cannot be embedded
into metal mounting fixtures completely. They are susceptible
to the influences of the surrounding metals because their magnetic
sensing fields protrude from the sides of their sensing faces.
This is what gives them their extended sensing capabilities. Not
embeddable inductive proximity sensors must be mounted into a
metal free area.
The free area on each side of the sensor must be equal to the
sensor’s diameter. The depth clearance from the device’s
sensing face must be two times the sensor’s standard detection
distance. By following these rules, you can reduce the chances
of false detection and reduced sensing distances.
Features Summary
• Very good for small detecting ranges, typically one inch
or less.
• Circuity is protected by a rugged, epoxy-full housing.
• Inductive proximity sensors will detect metals.
• Inductive sensors have a wide range of input voltages,
10 to 30 VDC and beyond are typical.
• Starting at 100,000 hours, the inductive electrical life
is long.
• The cylindrical bodied inductive sensors are easy to setup.
• They are relatively strong against temperature extremes
from –25 C to 70 C.
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