The Inductive and Capacitive Sensor | Different types and applications

Summary

The 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

• 🔧 Sensors like capacitive and inductive sensors are widely used in industrial processes.
• 🧪 Capacitive sensors detect liquid levels, while inductive sensors detect if containers are covered.
• ⚙️ Inductive proximity sensors detect ferrous metal objects without physical contact, and they can also detect non-ferrous metals but at reduced distances.
• 🔄 The sensing range of inductive sensors varies by material and can be found in the sensor's datasheet, typically no more than 80mm.
• 📏 Hysteresis, the difference between activation and deactivation points, helps prevent bouncing between sensor states.
• 🛠️ 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.
• 📡 Capacitive sensors rely on changes in electrostatic fields and capacitance to detect objects, while inductive sensors use electromagnetic fields.
• 🔌 Both sensor types can be configured as normally open or closed, with PNP or NPN wiring options, typically powered by DC voltage.
• 🔍 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

00:00

🛠️ 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.

05:00

🔧 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.

📏 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.

🔍 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.

🔁 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.

🌊 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.

🔧 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.

⚙️ 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.

📺 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.

Keywords

💡Capacitive Sensor

A capacitive sensor is an electronic device used to detect non-metallic materials such as plastic, wood, glass, and liquids. It works by detecting changes in electrostatic fields when an object alters the capacitance near the sensor. In the video, it's used to measure the liquid level inside a container, showcasing its application in automation and industrial processes.

💡Inductive Sensor

An inductive sensor detects the presence of ferrous (metallic) objects by generating an electromagnetic field. When a metal object enters this field, an induction current is created, which the sensor detects. The video describes its use in detecting metal lids on containers, emphasizing its role in non-contact object detection in industrial environments.

💡Hysteresis

Hysteresis refers to the difference between the activation and deactivation points of a sensor when detecting an object. It prevents the sensor from toggling rapidly between states, ensuring stable detection. In the video, hysteresis is important for ensuring accurate detection distances, particularly in applications like detecting container lids.

💡Shielded vs Unshielded Sensors

These are two configurations of sensors based on the presence of a metallic shield around the sensor coil. Shielded sensors limit detection to the front of the sensor, allowing flush installation, while unshielded sensors have a wider detection area but require non-flush installation. The video highlights this distinction in the context of installing inductive sensors in different setups.

💡PNP and NPN Configuration

PNP and NPN refer to the electrical configuration of sensors in DC circuits. PNP sensors source current to the load when activated, while NPN sensors sink current. The video discusses this in relation to how inductive and capacitive sensors are wired to external devices like PLCs, with a focus on their use in automation systems.

💡Oscillator

The oscillator is a critical internal component of both capacitive and inductive sensors. It generates the electromagnetic or electrostatic field necessary for object detection. In the video, the oscillator in an inductive sensor enables the detection of metal objects, while in a capacitive sensor, it reacts to changes in capacitance caused by nearby materials.

💡Detection Range

Detection range refers to the maximum distance at which a sensor can detect an object. For inductive sensors, this range varies depending on the material, with ferrous metals being detected at a longer range than non-ferrous ones. Capacitive sensors can detect a wide variety of materials, but their range is influenced by factors such as material type and environmental conditions.

💡Normally Open vs Normally Closed

Normally open and normally closed are terms that describe the default state of a sensor’s output. A normally open sensor closes its contact when it detects an object, while a normally closed sensor opens its contact. The video explains these configurations in the context of sensor output behavior, which is critical in automation systems for signaling object detection.

💡Switching Frequency

Switching frequency refers to how quickly a sensor can detect and respond to objects. Inductive sensors, for example, can operate at high switching frequencies, making them suitable for fast-moving processes. The video highlights this feature when discussing the use of inductive sensors in environments where objects may pass by at high speeds.

💡Electromagnetic Induction

Electromagnetic induction is the principle by which inductive sensors detect metallic objects. When a metal object enters the sensor’s electromagnetic field, a current is induced in the object, which changes the sensor’s oscillation and triggers detection. The video uses this concept to explain how inductive sensors detect the presence of metal lids on containers.

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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