The Inductive and Capacitive Sensor | Different types and applications
Summary
TLDRThe video explains the working principles of capacitive and inductive sensors used in industrial automation. Inductive sensors detect metallic objects by generating electromagnetic fields, while capacitive sensors detect various materials by altering electrostatic fields. The video covers the components of each sensor, their configurations (shielded/unshielded, normally open/closed, PNP/NPN), and their applications, such as detecting liquid levels or container lids. It also compares the strengths and limitations of both sensor types in different environments, making it ideal for automation and control systems.
Takeaways
- đ§ Sensors like capacitive and inductive sensors are widely used in industrial processes.
- đ§Ș Capacitive sensors detect liquid levels, while inductive sensors detect if containers are covered.
- âïž Inductive proximity sensors detect ferrous metal objects without physical contact, and they can also detect non-ferrous metals but at reduced distances.
- đ The sensing range of inductive sensors varies by material and can be found in the sensor's datasheet, typically no more than 80mm.
- đ Hysteresis, the difference between activation and deactivation points, helps prevent bouncing between sensor states.
- đ ïž Inductive sensors can be shielded (detect only at the front) or unshielded (wider detection area) and have various mounting options like flush or non-flush.
- ⥠Capacitive sensors can detect a wide range of materials beyond metals, including plastic, glass, and liquid, and are used for level sensing.
- đĄ Capacitive sensors rely on changes in electrostatic fields and capacitance to detect objects, while inductive sensors use electromagnetic fields.
- đ Both sensor types can be configured as normally open or closed, with PNP or NPN wiring options, typically powered by DC voltage.
- đ Capacitive sensors are adjustable via a bolt to fine-tune detection distance, making them versatile for different applications.
Q & A
What are the main functions of capacitive and inductive sensors in industrial processes?
-Capacitive sensors detect the filling level of liquids, while inductive sensors detect if containers are covered by detecting the presence of metal lids.
How does an inductive proximity sensor detect metal objects?
-An inductive proximity sensor detects metal objects by generating an electromagnetic field through an internal coil. When a metal object enters this field, an induction current flows in the metal, which the sensor detects as a change in oscillation, triggering a detection signal.
Can inductive sensors detect non-ferrous metals? If so, how does this affect the sensing range?
-Yes, inductive sensors can detect non-ferrous metals like brass, aluminum, and copper, but the detection range is reduced when compared to ferrous metals.
What is hysteresis in the context of inductive sensors, and why is it important?
-Hysteresis refers to the distance between the activation point and the deactivation point of the sensor. It is important because it prevents the sensor from 'bouncing' between states, ensuring stable detection.
What is the difference between shielded and unshielded inductive sensors?
-A shielded inductive sensor has a metal shield around the coil, limiting detection to the front of the sensor, while an unshielded sensor has a larger detection area, as the coil is not shielded, allowing detection from the sides.
What are the wiring configurations for inductive sensors, and how do they work?
-Inductive sensors typically have three wires: brown (positive power), blue (negative power), and black (signal output). The sensors can be NPN or PNP, referring to the type of transistor used in the sensor's output stage.
What types of objects can capacitive sensors detect?
-Capacitive sensors can detect various materials, including ferrous and non-ferrous metals, plastics, glass, wood, paper, and liquids. They are not limited to detecting metallic objects like inductive sensors.
How do capacitive sensors detect objects?
-Capacitive sensors detect objects by emitting an electrostatic field from dielectric plates. When an object approaches, it alters the capacitance in the field, triggering the sensor to send a detection signal.
What factors affect the detection range of capacitive sensors?
-The detection range of capacitive sensors is influenced by the material of the object, the environmental conditions, and the distance. Many sensors include an adjustment feature to fine-tune the detection distance.
What are the key differences between inductive and capacitive sensors in terms of detection and application?
-Inductive sensors only detect metallic objects and are robust in harsh environments, while capacitive sensors can detect a wider range of materials, including non-metallic objects, but are more sensitive to environmental factors like humidity.
Outlines
đ ïž Overview of Sensors in Industrial Automation
The first paragraph introduces the use of sensors in industrial processes, highlighting the capacitive and inductive sensors. It explains that capacitive sensors are used to detect liquid levels, while inductive sensors are used to detect if containers are covered. The paragraph promises a closer examination of how these sensors function in automation, starting with a detailed explanation of the inductive proximity sensor.
đ§ Working Mechanism of Inductive Proximity Sensors
This paragraph delves into the working of inductive proximity sensors. It describes them as electronic devices capable of detecting ferrous metal objects at a distance without physical contact. The sensors can also detect non-ferrous metals like brass and aluminum, though at a reduced range. The paragraph explains the internal components of the sensor, including the coil, oscillator, trigger circuit, and output circuit. It further elaborates on the electromagnetic field created by the coil and how the sensor detects changes in the oscillation state when metal objects enter the field, triggering a detection signal.
đ Importance of Hysteresis in Sensor Operation
This section introduces the concept of hysteresis, which refers to the interval between the detection and deactivation points of an inductive sensor as a metallic object approaches or moves away. The paragraph highlights hysteresis as a critical factor in preventing bouncing between operating states and ensuring stable sensor performance. It provides an example of how hysteresis affects sensor placement and detection in automation systems.
đ Differences Between Shielded and Unshielded Sensors
The paragraph explains the difference between shielded and unshielded inductive sensors. Shielded sensors have a metal shield around their coil, which limits detection to the front of the sensor, making them ideal for flush installations. Unshielded sensors, on the other hand, have a larger detection area due to the lack of a metallic shield and must be installed non-flush to avoid interference from the surrounding metal structure.
đ Sensor Configurations: Normally Open vs. Normally Closed
Here, the text discusses different configurations for sensors, focusing on 'normally open' and 'normally closed' types. It explains that in a normally open sensor, contacts close to send a signal when a metal object is detected, while in a normally closed sensor, contacts open when detection occurs. These configurations define how sensors send signals in response to objects within their range.
⥠NPN and PNP Sensor Configurations
This section covers the NPN and PNP configurations of sensors, specifically those powered by direct current (DC) voltage. It explains how the sensors typically have three wires: a brown wire for the positive power supply, a blue wire for ground, and a black wire for signal output. It emphasizes the importance of wiring in the sensor's functionality and mentions that further videos will provide more detail on connections.
đ Capacitive Sensors: Detecting More Than Metals
This paragraph introduces capacitive sensors, noting their ability to detect not just metals but also materials like plastic, wood, glass, and liquids. It explains that capacitive sensors detect changes in electrostatic fields rather than magnetic fields like inductive sensors. The internal components of a capacitive sensor, such as dielectric plates and an oscillator, are discussed, explaining how these parts generate and react to electrostatic fields when objects are detected.
đ§ Adjusting Capacitive Sensors for Accurate Detection
This paragraph explains the adjustable detection range of capacitive sensors, influenced by factors such as object material, environment, and distance. It describes how to modify the sensor's sensitivity using an adjustment bolt, allowing it to detect objects, such as liquids, within containers. The flexibility of capacitive sensors to be fine-tuned based on application requirements is emphasized.
âïž Comparing Inductive and Capacitive Sensors
This section compares the characteristics of inductive and capacitive sensors. Inductive sensors are more robust, capable of detecting only metallic objects, and are resistant to harsh environments, while capacitive sensors can detect a wider range of materials, including non-metals, but are more sensitive to environmental factors like humidity. The differences in their application, durability, and sensing capabilities are highlighted.
đș Conclusion and Further Resources on Sensors
In the final paragraph, the speaker concludes by summarizing the key points discussed about inductive and capacitive sensors. They reiterate the availability of related videos on instrumentation and control, inviting viewers to explore further resources for more detailed explanations. The video ends with a farewell message.
Mindmap
Keywords
đĄCapacitive Sensor
đĄInductive Sensor
đĄHysteresis
đĄShielded vs Unshielded Sensors
đĄPNP and NPN Configuration
đĄOscillator
đĄDetection Range
đĄNormally Open vs Normally Closed
đĄSwitching Frequency
đĄElectromagnetic Induction
Highlights
Capacitive and inductive sensors are used widely in industrial processes, each with specific detection capabilities.
Capacitive sensors detect the filling level of liquids, while inductive sensors detect whether containers are covered.
Inductive proximity sensors can detect ferrous metal objects at a distance without physical contact.
Some inductive sensors can also detect non-ferrous metal objects, such as brass, aluminum, and copper, but with reduced detection range.
Inductive sensors have four main external parts: the sensor face, sensor body, indicator light, and connecting wires.
Inside the inductive sensor, a coil, oscillator, trigger circuit, and output circuit enable detection through electromagnetic induction.
Hysteresis is the difference between the activation and deactivation points of a sensor, preventing bouncing between sensor states.
Inductive sensors can be shielded or unshielded, with shielded sensors having a limited detection area to the front.
Capacitive sensors can detect a variety of materials beyond metals, including plastic, glass, wood, and liquids.
Capacitive sensors operate based on electrostatic fields, with internal dielectric plates creating a detection zone.
The detection distance of capacitive sensors can be adjusted using a control bolt to fine-tune sensitivity.
Inductive sensors are resistant to environmental conditions like shocks, vibrations, and dust, with a high switching frequency for fast detection.
Capacitive sensors are susceptible to humidity and dense vapors, but can detect objects through non-metallic walls.
Both inductive and capacitive sensors are available in normally open, normally closed, PNP, and NPN configurations.
Capacitive sensors are widely used for level sensing, especially in plastic bottles and short-range detection of transparent materials.
Transcripts
sensors are used in almost all
industrial processes
capacitive sensor and inductive sensor
are some of them
the capacitive sensor for this case
detects The Filling level of the liquid
while the inductive sensor detects if
the containers are covered
let's take a closer look at how the
different types of capacitive and
inductive sensors work and some of the
ways these sensors are used in
automation
firstly let's see about the inductive
proximity sensor
an inductive sensor is an electronic
device that can detect ferrous metal
objects at a given distance without
physical contact
some inductive sensors can also detect
non-ferrous metal objects such as brass
aluminum and copper
although the detection range or distance
of an inductive sensor on non-ferrous
material objects decreases
the sensing distance depending on the
material of the object can be found in
the data sheet of the sensor
although this distance is not more than
80 millimeters
the four main external parts of an
inductive sensor are
the sensor face the sensor body the
indicator light and the connecting wires
inside the sensor body is where the
circuitry that makes the sensor work is
located
in it we find a coil an oscillator the
trigger circuit and the output circuit
the current oscillator allows the coil
to generate an electromagnetic field
in this way when the metal object enters
the electromagnetic field an induction
current or Cold current flows in
the metal object due to electromagnetic
induction
as the object approaches the sensor the
induction current flow increases causing
the load on the oscillation circuit to
increase
then the oscillation Fades or stops
the sensor detects this change in
oscillation state with the amplitude
detection circuit and outputs a
detection signal
in this way it works by detecting the
metal lid of the container in the
process shown above
when choosing a sensor we must take
hysteresis into account
but
what is it
when the metallic object approaches the
sensor it reaches a point where it is
detected and the sensor sends an
activation signal
now when the object moves away the
sensor will continue to detect it up to
a certain distance which we will call
the deactivation or switching distance
when moving away
so the interval between these two points
is known as hysteresis
which we must take into account when
placing the sensor and the object to be
detected
hysteresis is important because it
prevents bouncing between operating
states of the sensor
inductive sensors are available in many
different configurations
they can be shielded or unshielded
a sensor is shielded if its inner coil
has a metallic Shield
here we can see the internal
configuration of the sensor in a cross
section
this Shield is cylindrical in shape and
covers the entire Contour of the sensor
coil
in this way the detection of the object
is limited only to the front of the
sensor
whereas an unshielded sensor has a
protruding face and inside the coil does
not have a metal shield around it
therefore it has a much larger census
area
the installation of the sensors can be
flush if it is a shielded sensor
in this case the face of the sensor is
flush with the metal structure where it
is installed
since the metal structure does not
affect its operation
whereas if the sensor is not shielded
its installation necessarily has to be
non-flush that is the active face of the
sensor goes out and its operation is not
affected by the metal structure that
supports it
there are also other settings
a sensor can be normally open or
normally closed
if a metallic object approaches the
normally open sensor it detects the
object and closes its contact sending a
high level signal to its output
if a metallic object approaches the
normally closed sensor the sensor
detects the object and opens its contact
sending a low-level signal to its output
another configuration in the sensors is
that it is npn or PNP
for this case I am considering sensors
that are powered by a direct current
voltage but there are also alternating
current ones
they usually have three cables
the brown wire connects to the positive
power supply the blue or light blue wire
connects to zero volts or negative power
and the black wire is where we get the
signal from the sensor which connects to
the load which can be a relay a PLC or
any other controller
in another video we will detail the
connections that need to be made
I will leave the links in the
description
the capacitive sensor
its external appearance is very similar
to the inductive sensor since it
consists of the same parts
but the difference is that it not only
detects ferrous metal objects it can
also detect any other objects like
plastic mineral glass wood paper liquid
Etc
as we can see one of the applications is
that it is used to detect the level of
the liquid contained in a glass
container
capacitive proximity sensors react to
alterations in electrostatic Fields
since these are based on dielectric
principles of capacitance to establish a
detection field near the face of the
sensor that creates a detection Zone
it must be remembered that the inductive
sensors that were previously seen react
to changes in magnetic fields
internally the sensor consists of
dielectric plates with a certain
capacitance on the detector face which
is responsible for emitting an
electrostatic field
the other important parts of the sensor
are
the oscillator which is responsible for
generating waves at a certain frequency
the trigger circuit which is activated
when it detects the object
and finally the output which is where
the signal is digitized
when an object approaches the sensor it
produces changes in capacitance which
Alters the sensor's electrostatic field
the oscillator for its part remains
inactive when the object is outside the
electrostatic field produced by the
dielectric plates
but if an object gets closer then the
oscillator moves at maximum frequency
and amplitude
if the object moves away the oscillator
returns to its default state
the detection distance depends on
several factors
these include the material of the object
to be detected the application
environment and the distance from which
the detection is to be performed
although most sensors come with an
adjustment Bolt
for example
if the liquid in the container is not
detected then the bolt must be rotated
to adjust the detection distance of the
material or object
capacitive sensors just like inductive
sensors are also available in many
different configurations
among them we can see that they can be
normally open and normally closed
in addition to being PNP configuration
and npn configuration
there are also shielded and unshielded
sensors
let's look at the features similarities
and differences between these two types
of sensors
inductive sensor
detects only metallic objects
relatively low range which will vary
depending on the nature of the alloy
robust and resistant in hostile
environments unalterable against shocks
and vibrations dust Etc
relatively High switching frequency
which makes it possible to control the
passage of parts at high speed even in
rotation
no moving Parts subject to where
capacitive sensor
detects ferrous metals and any other
type of material
they can detect objects through
non-metallic walls
alterable against humidity and dense
Vapors
widespread use for level sensing for
example through plastic bottles and for
short-range sensing of transparent
materials
absence of mechanical wear and long
useful life regardless of its use
well friends here is this explanation
remember that on the channel you can
find videos related to instrumentation
and control
bye
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