Limit Switch Explained | Working Principles

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In this video, we’re going to introduce you to a device called a Limit Switch.
There’s probably not a day that goes by where you don’t use or encounter a limit switch at home, or at your workplace.
There are 4 general types of limit switches: whisker, roller, lever, and plunger.
Depending on the application, a limit switch may be a combination of 2 of the general types such as roller-lever.
A limit switch is an electromechanical device operated by a physical force applied to it by an object.
The limit switch is used to detect the presence or absence of an object.
These switches originally used to define the limit of travel of an object, and as a result, they were named Limit Switch.
When you open the fridge door, a light comes on inside. A limit switch is used to detect if the fridge door is open or closed.
On many overhead garage doors, there is a limit switch that stops the movement of the door when it reaches its fully opened position.
A limit switch is an electromechanical device consisting of an actuator mechanically linked to an electrical switch.
When an object contacts the actuator, the switch will operate causing an electrical connection to make or break.
Limit switches are available in several switch configurations: Normally Open, Normally Closed, or one of each.
Depending on the origin of the electrical schematic, you may see limit switches drawn in different ways.
The International Electrotechnical Commission (or IEC) and the National Electrical Manufacturers Association (or NEMA) have slightly different symbols.
Let’s have a look inside a microswitch that is a type of limit switch.
A microswitch has 2 limit switches operating together and sharing a common terminal. One limit switch is normally open and the other is normally closed.
To be technically correct, the switch configuration is Single Pole Double Throw, or commonly referred to as SPDT.
The dashed line indicates that both switches are mechanically connected and will operate at the same time.
Alright, let’s connect the microswitch to a lamp circuit. In the inactive state, the Red lamp is on as the device is not being operated by an object pushing on the trigger.
When the Trigger is pushed the device will activate, and the Green lamp will come on.
Now that you’ve seen the limit switch in action you are probably thinking about some of the applications where you have seen them in action.
For example, you might see a limit switch operated by a container on an assembly line, or operated by a rotating machine part or by any number of other moving mechanical objects.
A limit switch could be used to count passing objects, or determining the position of a hydraulic cylinder.
Limit switches are slowly starting to disappear from many industrial applications. They are being replaced by proximity sensors.
Unlike a limit switch, a proximity sensor has no mechanical moving parts.
A proximity sensor performs the switching action with electronic switches.
Limit switches will not completely disappear any time soon as they outshine their proximity switch counterpart in their ruggedness and reliable operation in difficult environments.
Generally speaking, limit switches are capable of handling much higher current values than proximity sensors.
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What is a Sensor? realpars.com/types-of-sensors/
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[@_desertwalker_]

Using the light globes to demonstrate how they worked brought it home for me. Many thanks.

[@realpars]

Glad to hear that! You're very welcome

[@jedijedi4211]

Your videos are extremely helpful and very well explained. Thank you for your efforts in teaching us automation concepts. Good luck and cheers!

[@realpars]

You are more than welcome, Jedi! Happy learning!

[@roseelectronics4582]

The best technical video channel. Truly

[@realpars]

Thanks a lot!

[@kor_js_kim]

For your better understanding, the limit switch is devided in two parts mechanical and electrical parts. in the application, if you want to proper goods, please remember the mechanical parts related "how the mechanism works", and electrical parts deal with "system capacity" such as current and voltage rate. Espatially in the motor involved one, you can calculate inducted current level with the power facter. lats of cases has burning issue of contacts for too high electric level. thank you for the great information and good luck for everyone who wants to know limit switches! :)

[@realpars]

Hi JS Kim, Great addition! Thanks for sharing your knowledge with us. Happy learning!

[@yongkim9446]

I'm working in control valve company. very helpful clips.many thanks🙏

[@realpars]

That's amazing, thanks for your support!

[@shridancediaries]

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[@realpars]

Thank you!

[@isaacdzokoto-jnr6306]

Thank you.... Very helpful

[@samsarajunvianto8632]

thank you for the content, it is very useful for me, an electrical student, greetings from Indonesia 🙏

[@realpars]

Glad it was helpful! Happy learning

[@thetmon4109]

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[@realpars]

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[@IngDzib]

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[@realpars]

Our pleasure, Wilberth! Happy learning.

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[@realpars]

Thanks for your comment!

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Going to start a limit switch conservancy group 😋

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[@atirjan8320]

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[@realpars]

Great! Happy learning.

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[@realpars]

You're very welcome, and best of luck!

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That's good,thank you for information and all everything for students in indonesia keep goin mr abi 🙏🙏👌

[@realpars]

Thanks for your support, Putra!

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[@realpars]

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[@yale7921]

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[@realpars]

Thanks a lot, Muhammad!

[@KevinNguyen-tw5ml]

Thank you very much !

[@realpars]

Our pleasure, happy learning!

[@milkyway808]

Very nice video

[@nabillaazzahra916]

Wow the video is very useful, thank you, I'm a student from Indonesia🇮🇩

[@realpars]

Glad to hear that! Happy learning, Nabila!

[@dilawarejaz9893]

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[@realpars]

Glad it was helpful!

[@11-muhammadawaluddin83]

Thanks for the information, this video is great.

[@realpars]

You're welcome!

[@2loco]

Excellent. Thanks. Maybe machine safety would be a good next topic to discuss. I.e saftey limit switches, door locks, interlocks, push buttons, light curtains, saftey monitoring relays, saftey contactors etc. Thanks

[@realpars]

That's a great topic suggestion! Will surely pass that on to our course developers. Thanks for sharing and happy learning!

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[@realpars]

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[@realpars]

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[@realpars]

Glad it was helpful!

[@md.aliakbar5646]

thanks a lot dear Real Pars

[@realpars]

You're more than welcome, Ali!

[@prajnasmitadas1997]

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[@realpars]

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[@realpars]

Glad to hear that!

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[@realpars]

You're very welcome!

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[@realpars]

Glad it was helpful!

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[@realpars]

Our pleasure, Sultan!

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[@realpars]

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[@mohammadfarzankia2636]

Well done 🎉

[@realpars]

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[@realpars]

Thank you too!

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[@realpars]

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[@bayuues101]

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[@realpars]

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[@Ashok_incredible_learning]

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[@realpars]

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[@jamalalsheili7139]

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[@realpars]

Thanks a lot, Jamal!

[@Billups7Iniesta8C7]

Awesome presentation. Total noob here learned what a limit switch is and does in like 3 minutes.

[@realpars]

Glad it was helpful!

[@radenfarhan9525]

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[@realpars]

Thanks a million for your support, Raden!

[@entertainmentandknowledge6054]

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[@realpars]

Thank you, Sachin!

[@Dazai99274]

thanks

[@realpars]

You're very welcome

[@davidf.restrepoasprilla7224]

Thanks for the video. Bro, do you draw the components yourself or is there an image platform or something to get them? If you draw them I would love to know what software or app you use. Thanks!

[@realpars]

Hi David, Thanks for your comment! Regarding your question, I am actually not sure about that as all our visuals are created by our graphic and animation department.

[@vikaseratechvlog2116]

Nice 🙂

[@realpars]

Thank you!

[@ibmtpx24]

1:17 wait if the limit switch for the garage door is triggered (door is rolled up), how does it roll down then after the power to the motor is already cut?

[@realpars]

Hi @teetee tee. Thanks for reaching out. There are a number of different configurations allowing for the door to be closed. In most cases, the motor is a reversing type. Once the upper limit is triggered, the motor driving the door in the open direction is stopped. This limit switch may also be part of a permissive circuit that activates the down motor when a "Close" switch is operated. There will be a limit switch at the bottom of the door as well to stop the down motor.

[@tamaoserizawa8126]

That cool

[@wokeclub1844]

Wooaahhh.. I came here from Google and this was uploaded just 14 hours ago!

[@johnkoester7795]

Can a limit switch also be used for a pull string doll?

[@realpars]

Hi John. I'm not sure I understand your question. Can you elaborate please?

[@fauzanakbar768]

the video is interesting and the teacher is handsome

[@abhishektiv4400]

Any Disadvantages of limit switch???

[@realpars]

That would make for a great topic suggestion! I will happily go ahead and forward this to our course developers for future video courses.

[@abhishektiv4400]

@@realpars please go ahead. Also wanted to know about Photocells(Diffuse type) working on Dark-black colour.

[@filimniko]

👍

[@senthilkumarj2439]

How to download step 7 software it's free or not

[@realpars]

Hi Senthil, Thanks for your comment! We do not have a link to download the STEP7 software for free. However, we do sell a variety of hardware and software in our online store, including STEP7. Feel free to have a look around marketplace.realpars.com/search?type=article%2Cpage%2Cproduct&q=step7* Hope this helps! If I can be of any further assistance, please let me know - I’m more than happy to help!

[@senthilkumarj2439]

I am not able to download

[@mareysaad6597]

Fucking amazing

[@sunimalfernando4347]

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[@George-iz2ce]

While this video has many good parts, it would be better if you didn't try to draw its length by speaking over-simplistically (how is that done? you guessed it) and not rehearsing the exact same things toward the end while never explaining what is the whisker or the plunger switch.

[@realpars]

Hi George, Thank you for sharing your feedback with us, I will make sure to pass this on to our course developers. Thanks for sharing and happy learning!