30
Proximity Sensors,
Inductive Sensors,
cylindrical
1
.1.1
Proximity Sensors,
Inductive Sensors,
rectangular types
1
.1.2
Proximity Sensors,
Inductive Sensors,
slot types
1
.1.3
Proximity Sensors,
Inductive Sensors
1
.1
Proximity Sensors,
Inductive Sensors,
ring types
1
.1.4
Proximity Sensors,
Inductive Sensors,
Rotational Speed Monitors
1
.1.7
Proximity Sensors,
Inductive Sensors,
Valve Position Sensors
1
.1.5
Proximity Sensors,
Inductive Sensors,
Clamping Systems Sensors
1
.1.6
Proximity Sensors,
Inductive Sensors,
Valve Position Sensors ( Accessories)
1
.1.5
Germany: +49 621 776-4411
Consider the General Notes on the Information in the Pepperl+Fuchs Product Catalogs
Pepperl+Fuchs Group
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USA: +1 330 486 0001
fa-info@us.pepperl-fuchs.com
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Copyright Pepperl+Fuchs
Assured operating distance s a
Distance from the active area where actuation of the proximity switch is
assured under defined conditions:
.0
< sa ≤ 0.81 · s n
Repeatability R
Change in the actual operating distance sr, measured over a period of
eight hours at a housing temperature of 23 ± 5 °C, any level of relative
humidity and a supply voltage of Ue ± 5% or any voltage within the rated
operational voltage range ± 5%:
R ≤ 0.1 ·s r
Hysteresis H
Distance between the trip points when the measuring plate approaches
and moves away from the proximity switch. It is specified relative to the
actual operating distance sr, measured at an ambient temperature of 23
± 5 °C and rated operational voltage:
H ≤ 0.2 · s r .
Safely switched off
A proximity switch is switched off safely when the distance between the
measuring plate and the active area is at least three times the rated op-
erating distance sn .
Sideways approach
Above, the focus is on an axial approach to the standard measuring plate.
However, if you move the plate sideways into the active zone, you obtain
another operating distance s depending on the axial offset. This correla-
tion characterizes the response curve.
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Different actuator sizes
Inductive sensors are used to check machine parts in many cases.These
very rarely have the same size and shape as the standard measuring
plate to which the sensor's technical data applies.The operating distance
in particular depends on the size of the metal used to attenuate the sen-
sor.
Generally the operating distance increases only marginally with a larger
object surface, but reduces significantly for smaller objects.
If the object being checked is different in size to the standard measur-
ing plate, it is recommended that you verify the operating distance of the
selected sensor.
Different actuator materials
In addition to the actuator's dimensions, the material property of the ac-
tuator is also of considerable importance. This is characterized by the
reduction factor. The reduction factor specifies by what factor the operat-
ing distance reduces as a result of different materials versus steel FE 360
(
St37) for inductive proximity switches and against a grounded plate for
capacitive proximity switches. The lower the reduction factor, the shorter
the operating distance for the material in question. Since the reduction
factor for inductive proximity switches depends upon the housing and
shielding material, this factor vary from type to type. Please use the value
in the respective data sheet.
In the case of inductive proximity switches, the conductivity/permeability
ratio of the actuator is the parameter for the reduction factor. Some typical
reduction factor values are provided below:
Material
Reduction factor
Construction steel
1
Aluminum foil
1
Stainless steel
0.85
Aluminum
0.4
Brass
0.4
Copper
0.3
Step 3: Mounting conditions
Inductive and capacitive sensors can be flush mounted or non-flush
mounted.
Sensors that cannot be flush mounted
The largest possible operating distance (in reference to the diameter D
of the active area) is reached by sensors that cannot be flush mounted.
In the case of an inductive sensor, coils are used to generate electromag-
netic fields. To achieve a forwards or backwards
field alignment, the coils are embedded in a pot core. Despite this mea-
sure, part of this field is emitted laterally
and is affected by the surrounding metal. This lateral effect is also ob-
served with capacitive sensors.
To prevent sensors with a wide detection range from being attenuated
by the surrounding metal, clearance must be created around the sensor
element.
The size of the clearance can also be determined from the technical data
for the respective sensors.
Sensors that can be flush mounted
Sensors that can be flush mounted do not require any clearance. (A=0).
The advantage of these sensors over ones that cannot be flush mounted
is that
they are better mechanically protected and are less sensitive to interfer-
ence. However, one disadvantage is the shorter operating distance as
the active area
of the sensor is already surrounded by metal. The sideways interference
from the surrounding metal is reduced by a special internal shield,
but this happens at the detriment of the detection range. These sensors
achieve only approx. 60% of the operating distance of non-flush designs.
D
B
F
A
A = 2 x operating distance
Non-flush mountable
sensor, installed correctly
Flush mountable sensor,
installed correctly
B = 3 x diameter
Further details on the mounting conditions are included in the technical
data for the sensors.
Proximity Switches
