What is a Contactor? | Working Principles

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It's been more helpful this channel than my career in more than one aspect.

[@realpars]

What an amazing compliment! Many thanks

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Totally Agree 🙏

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I'm going through the greatest challenge of my life: becoming an automation engineer in a industrial plant. I've got a degree in electrical engineering, which was more related to power supply systems, but not so much to automation... however, I accept the challenge anyway! And I have to thank You for sharing this knowledge in a so wonderful way! It's been very helpful for beginners like me!

[@realpars]

We truly appreciate your support, Leandro! We're happy to hear that our video courses are helping you. If you have any questions along the way, please feel free to reach out.

[@kenmichaels6595]

Probably one of the most lucid presentations on contactors I've run across. Great job!

[@realpars]

Thank you very much, Ken! Much appreciated

[@Sanjay.M.Pillay]

I am in industrial automation domain from last 2 years and have referred many videos. But the quality and vibrancy of Realpars videos us exceptional ❤

[@realpars]

Thank you so much!

[@davidalvarado7944]

This was so helpful and helped me embarrass my lead for trying to troubleshoot a broken contactor incorrectly when it was working just fine!!! thanks a bunch RealPars

[@realpars]

You're very welcome, David! Glad to hear that our video course has been helpful!

[@bmtamer77]

In the past year I have seen many Hvac videos. This is by far one of the best channels I subscribed to. I promise to share with some of my school mates. Thank you sir! Respect and keep the knowledge flowing on a high pressure gauge!

[@realpars]

Thanks for sharing!

[@mahuk.]

So glad I found this channel when I was starting my career. Your videos are always so easy to understand with the good narrative and the images. Than you so much. One day I'll come back to buy your courses even if I don't need them at that point.

[@realpars]

Amazing compliment, many thanks!

[@iliapopovich]

Very well explained in American-English, recently I did a L3 PLC programming in UK and it was horrible. Anyway, I took the certification...And by the way regarding the contactors and relays, you can always put three relays instead of a contactor for some small motors temporarily, just check the ampers. I have an Arduino controller with 230v 10A ,very small relays working even on 3.3v DC, so with them, I can easily switch On/Off a 1000W , 450V motor.

[@aryanrathi4876]

What if only one phase trips? Wouldn't that cause phase imbalance?

[@ricardogarcia3900]

Great video. Remember one thing. You must connect a thermal relay in series between the outputs of the contactor and the inputs of the motor, plus the output that indicates a overload as a signal to PLC.

[@miguelzavaleta1911]

At that point why not just use a VFD instead?

[@Cleofizoid]

...and now you have a motor starter and not a "contactor".

[@daruscole1586]

I Praise God and thank those who have designed and worked on (and may continue to do so) such things as this to make things safer and to help prevent damage to other things. I imagine that some or all of the specifics to the design of such things may have required much work and testing. God Bless them.

[@Xaerorazor0]

If I remember correctly, contactors use a bar across two contacts per line where it can split the voltage to prevent arcing, whereas a relay uses only one point where it will experience the full voltage drop across the contacts, when opening the circuit, so a relay will take damage when opening a higher voltage/higher current source when the contactor is designed to split the voltage across the 2 contacts and reduce possible damage from arcing.

[@sjholmesbrown]

This is correct. The contacts in a contactor are also larger than a small relay and have contact surfaces designed for higher currents. Often the contacts in a contactor will also 'wipe' or rub across each other slightly as they close, this serves to clean off slight oxidation traces and keep the contacts fresh.

[@danielfranchette5547]

the double breaking does not cancel the electric arc but helps to extinguish it, which will define the breaking capacity of the contactor. Much of the complexity of contactor design lies in implementing different arc breaking techniques in a minimal amount of space. it is this electric arc which determines the electrical life of the contactor (because of the progressive degradation of the contacts) which is much less than its mechanical life which is often around ten million operations. The electrical life depends on the type of load supplied by the contactor. An inductive load will generate larger arcs than a resistive load and decrease the longevity of the poles. The contactor manufacturer gives life curves as a function of use to provide for the replacement of devices.

[@clenlima]

Thank you! I'm from Brazil.

[@realpars]

Our pleasure!

[@KD_elctrcL_N_elctrnX]

One of the best explanations on contactors 👏

[@realpars]

Glad you think so!

[@Space_Tour1]

Amazingly simple and interactive way of explaining.

[@realpars]

Glad it was helpful!

[@dmj777]

What an excellent explanation of how a contact operates!🤩

[@realpars]

Thank you very much!

[@spacexnix]

this video explained the essence to me more than anything existing on KZbin

[@realpars]

That's amazing to read! Thank you so much for your kind support

[@QuestionableAdviser_]

When a YT video explains much more clearer than my Engineer Teacher.

[@od1351]

These videos are great,although you can be in maintenance field for many years it’s always some details and concepts you may miss but going back and studying and just doing a little research clears up a lot of the fog that can be in you’re head about certain things

[@realpars]

Thank you very much! We're very happy to hear that.

[@ekhlaskhan1356]

I am from Bangladesh and EEE engineer.ur video helps me a lot

[@realpars]

Glad to hear that! Happy learning

[@PeterKiiru-x8z]

Well thought out clear and concise presentation thanks very much

[@realpars]

Glad it was helpful! You're very welcome.

[@ashutoshsawant7013]

I have been waiting for contactor vs relay video since long. Thank you for this.

[@realpars]

Glad to hear that! You're very welcome.

[@АнтонКвасов-б1л]

RealPars you best! Real learn videos! Thanks!

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Glad you like them!

[@linetyo8769]

I'm very appreciated that you did this video. It's very helpful. I got the power & courage again. Thank you. I'll keep studying.

[@realpars]

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[@rico2207]

Perfect animation

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Thank you!

[@sajadgul]

Great explanation. Hat's off..

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Glad you liked it!

[@katuraysalad]

Thank you very much for this video

[@realpars]

Glad it was helpful! You're very welcome

[@tiagogamas7990]

Excellent video by RealPars!

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Thank you very much!

[@natesansrinivasan2590]

This channel is really damn helpful for technician and engineers working in industries..

[@realpars]

We're very happy to hear that, Natesan! Always feel free to leave us your questions if anything is unclear. Thanks a million for your support!

[@jelynmahinay]

very well explain. thank you sir.

[@realpars]

Glad you liked it!

[@gilbertocastrosustaita6307]

Amazing explanation!!!!very nice channel

[@realpars]

Thank you so much, Gilberto!

[@kasondensofwa4184]

Very lucid and audible, your videos are the best. How I wish you could have established a training center in Africa for hands on training 🤷🤷🤦 Kindly also do a video on electronic modules 🙏🙏

[@realpars]

Thanks for your kind comment, Kasonde! I will happily pass your topic suggestion on to our course developers.

[@shreyashsb5389]

I'm very confused about those,now I'm cleared. thank you

[@realpars]

Glad to hear that this video course helped you clear out the confusion. Happy learning and keep up the learning curve :)

[@themuddyrug55]

Very informative video, and you explained everything with no way to misinterpret the information. Very nice!

[@realpars]

Glad you enjoyed it!

[@RiaziMohandesi]

Very simple and understandable explanation thank you realpArs

[@realpars]

Glad to hear that, Ahmad! Happy learning

[@amadorcastro8497]

Thank you soo much you help me a lot

[@realpars]

We're so glad!

[@oficinadoeletricista]

Exceptional full scope of the content on the blog about the information about the contactors. Congratulations on your exquisite work.

[@realpars]

Many thanks!

[@Logicmart5754]

Hats off to you RealPars. What a nice way of explanation!

[@realpars]

Thanks a ton!

[@thomas8230]

Why did I only come across your channel now? Very well explained. Thanks

[@realpars]

Glad it was helpful! Thank you very much

[@travelthesoul]

Best video ever

[@realpars]

Thank you so much!

[@sbmtech8920]

Now am clearly understand about contractor and relay thank u realparas

[@realpars]

Glad it helped!

[@thewarlordscalling6537]

PLC stands for Programmable Logic Controller. They are industrial computers used to control different electro-mechanical processes for use in manufacturing, plants, or other automation environments.

[@billmichae]

The very best video on this topic!

[@realpars]

Thanks a lot, Bill!

[@ibimpepple]

Finally my question has been answered This is the best ❤

[@realpars]

Glad to hear that, Ibim! Happy learning

[@xxcrazymanxx1001]

Thank you so much for making this video I'm just starting my career in this feild and this video was very simple and helpful

[@realpars]

Glad it was helpful!

[@Bonejone213]

Love this channel

[@realpars]

Thank you!

[@logeshjeeva1231]

Your videos are very useful to learn and I would say that I like the way of teaching through the awe animated videos..Thanks.

[@realpars]

Happy to hear that!

[@sjholmesbrown]

A small correction for you. You stated a couple of times that most contactors use 24VDC for their coil. While these are used, the great majority I have seen in industry use 120-400VAC for their coil, with an interposing relay to convert the PLC's 24V output to a high voltage AC output for the contactor coil. I also would not directly connect a PLC output to a contactor unless they were specifically rated for it, as they are an inductive load and can generate large voltage spikes when turned off.

[@realpars]

Thanks for sharing that, Stephen!

[@cheoksc2231]

Really good video explaining things clearly and easy to understand. Many thanks.

[@realpars]

Glad it was helpful!

[@murzanovv]

Perfect explanation

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Glad you liked it

[@sunilthorat.youtube]

My fav KZbin channel. ❤️

[@joefanningartist]

Brilliant, very clearly explained, and very good visuals, thank you sir

[@realpars]

Glad it was helpful!

[@cep5618]

Excelent clear information. Congrat!

[@realpars]

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[@surendhar....]

Best experience

[@gyanamahendrasatapathy530]

Great explanation about contactor

[@realpars]

Glad you liked it!

[@annahabanna]

Fantastic intro to the topic! Thank you.

[@realpars]

Glad you liked it!

[@electricaltalent7385]

Very well explained I saw it many times easily understood thank you so much for this information..

[@realpars]

Glad to hear that! Thanks for your support

[@SanaataniArvindam]

Clearly understood sir thank you

[@realpars]

Glad to hear that!

[@perrmyint3098]

Clear and great video thank you for sharing your experience.

[@eugenepohjola258]

Howdy. Nice basic knowledge. However. I would be reluctant to connect a contactor coil directly to a PLC output. I would use a relay in between. Also a backfire or free-wheeling diode over the contactor coil is mandatory with DC. There is a lot of induction in the contactor coil when engaged. This energy will rapidly burn the relay or PLC card contacts if not managed. With AC the backfiring problem is not as big but some backfire managing is still necessary by a suitable RC filter over the coil. Typical values are R = 100 ohm and C = 100 nF 500 V in series. Regards.

[@realpars]

Thanks for sharing your knowledge and experience with us! We always appreciate such comments.

[@eugenepohjola258]

@Mindaugas Vaitiekūnas Yes. The backfire diode is a good solution in most cases. It is sometimes experienced that the contactor disegages too slowly as the back current takes too long to dissipate in the coil and the diode. A solution to this may be to use, say, 7 diodes in series. This will force the back induction to rise to about 5 V and provide a faster dissipation. The output transistor will see a voltage of 24 V + 5 V, or some 30 V but it will most likely tolerate that. One could consider using a regular diode and a 5 V zenerdiode in anti series but it is not recommended. Zener diodes are slow and will allow the build-up of a high spike before going into conduction. For the same reason Schottky diodes cannot be used. Regards.

[@ashkanmahouti858]

I’m convinced I just need to be told how things work the caveman style. I have papers on papers explaining how a contractor works. Learned nothing about how it works but the part names. Watched this video for 10 seconds and I already figured it out

[@realpars]

That's an amazing compliment, Ashkan! Thanks a lot for sharing, we are happy to hear that!

[@yousefalshorafa154]

thx!

[@zubairyamin6044]

this is an amazing and awesome video. keep it up sir. thanks for teaching us💖💓

[@realpars]

Thanks for your kind support, Zubair!

[@255205titel]

Nice introduction with the connection content of PLC, like it!

[@realpars]

Glad you liked it!

[@ernestoterrazas1132]

Hi! I really like your videos, congratulations for the excellent manner in which they are presented. They are an excellent training resource! One question: I keep seeing in your videos that you mention a -24V DC connection when in reality it should be 0V (M in schematics). When you say +24V in the positive connection, and then -24V in what should be the 0V (M), it gives the wrong impression of a net 48V potential across the supply of the contactor coil. I've seen other of your videos that also have this mistake (not exactly of contactors by the way). Am I missing something?

[@realpars]

No, you are not missing anything. Having designed and installed hundreds of panels over my career, I have seen a few different ways to identify the negative, or common, connection for 24VDC circuits. Technically, the return leg, or more negative connection, in a 24VDC circuit is identified as 0V, earth potential, or COMMON. However, some like to identify the common terminal as the (-) terminal or the negative terminal of the 24VDC circuit (-24VDC). This designation is designed to separate it from other grounds or earth potentials.

[@Cleofizoid]

I always say "DC Common" or "DCC".

[@user-ob7eb5sh5w]

Thanks you a lot

[@realpars]

You are welcome!

[@kuppilikiran654]

Simply superb sir 🙏🙏

[@realpars]

Thank you, Kuppili!

[@simozy4475]

Thank you for the great and simple explanation

[@realpars]

You're very welcome! Happy learning

[@SrOsvaldo1]

Thank You Real Pars

[@realpars]

You're very welcome!

[@nsjx]

really Appreciate the Basics 👋

[@realpars]

Glad you like them!

[@hamidaittaleb825]

Wonderful explanation. Thank you so much 👍

[@realpars]

Glad it was helpful!

[@prakash4826]

Impeccable teaching, thank you ❤️

[@realpars]

Glad it was helpful!

[@mixme8655]

Wow that's why i like all your videos

[@garokejelian565]

You have a very good way to describe

[@realpars]

Thank you, Garo!

[@gifarihasyim7776]

This video saved my careers. By the way, I have a question. Does A2 also connect to PLC? If yes, is the voltage connected to A2 have value of -24 V?

[@realpars]

A1 and A2 are the to connections in the contactor that actuate the coil, which in turn pulls in the contactor and allows current to flow from L1/L2/L3 to T1/T2/T3. As the video explained, the PLC I/O cards are not powerful enough to actuate the motor directly, so we use a contactor with a low-voltage coil, in this case a 24VDC coil. A1 is connected to +24VDC at the I/O card (the digital output terminal) and A2 is connected to 24 Common. Sometimes we refer to the common terminal as -24VDC, but it is truly a ground, or 0V potential point that is shared with the power supply. So when the digital output is energized, 24VDC flows to A1, and the coil is energized, pulling in the contactor. A connection to A2 is required to insure a steady 24VDC is applied to the coil (e.g., form a complete circuit).

[@siddhant14999]

❤ beautiful explanation

[@realpars]

Thank you!

[@maruthiprasad8184]

Thank you very much for valuable information. Kindly make a video on Different PLC programming languages available and their applications and their best uses. Thank you very much for taking the feedback and making the same.

[@realpars]

Hi Maruthi! Thanks for your comment and your suggestion. I will pass this on to our course developers! Thanks for sharing and happy learning!

[@sanelekabinde625]

Best video ever. Keep up the good work

[@realpars]

Thank you, Sanele!

[@speedbird7587]

Neatly explained, thanks!

[@realpars]

Glad you enjoyed it!

[@uzzaluzzal250]

Useful video thanks realpars

[@realpars]

Glad to hear that!

[@antipolicia1]

Thanks for the great video, I love your channel just wish you did more on AB.

[@realpars]

Thanks for your kind comment and feedback, Lukas! I will happily pass this on to our course developers.

[@xuanminhtran8547]

I realy love your videos, they are very helpful.

[@realpars]

Thanks a lot, Xuan!

[@udithabandara6382]

thank you, well explained

[@realpars]

Glad you liked it! Thank you for sharing

[@emmanuelflores1781]

Awesome video, great explained!

[@realpars]

Glad you liked it!

[@cletusasiwoko2368]

Hello Real Pars, I enjoy watching your videos. Undoubtedly, I have learnt a lot through them. I have a request. Can you please make a video on phase monitoring relay? I'm having a challenge understanding it. Thank you

[@realpars]

Great suggestion, Cletus! I will happily pass this on to our course developers. Thanks for sharing and happy learning!

[@palaash4]

Thank you

[@dirasalsabila02]

OMG thank you so much, this video is very helpful!!!

[@realpars]

You're so welcome!

[@abdullahmustafawi3165]

It was so helpful, thanks a lot!

[@realpars]

Glad to hear that! Thank you for sharing

[@alayshah6394]

Great Explanation 👍

[@realpars]

Glad it was helpful!

[@runbou3485]

អរគុណThank👏

[@ac4cars656]

Yes, video has been very helpful!

[@realpars]

Glad it was helpful!

[@Ahmed_Alhadi2022]

Well done good job , thank you

[@realpars]

Our pleasure!

[@sivaramank5016]

@8.10 normally stop switches will be NC..but in this video it is represented As NO

[@realpars]

True, Stop pushbuttons are normally NC contacts. However, for some installations, the START and STOP pushbuttons are both NO contacts brought into a PLC DI card, as in the video. In other installations, a single NO pushbutton is used to both START and STOP a motor. For single machine installations or shop-type installations, NO contacts are sometimes used when the E-STOP is in close proximity in case of failure.

[@lovesophia19]

I love this channel.

[@realpars]

Glad to hear that, Lola!

[@eis3nheim]

Amazing video, I really love this channel.

[@realpars]

Happy to hear that, Khaled!

[@ihab6292]

👍 so nice and easy. Thank you for good work.

[@realpars]

You're more than welcome, Ihab!

[@deepensharma7977]

Such a helpful video.

[@realpars]

Glad to hear that!

[@Amscid007]

Well explained, but I would have loved to know how the start and stop buttons are connected from the PLC via the 24VDC down to the Contactor.

[@realpars]

Hi Ehimemen, Thanks for the topic suggestion, I will definitely go ahead and forward this to our creator team. Happy learning!

[@sjholmesbrown]

kzbin.infosearch?query=starter Here is a search of @RealPars videos for 'starter'. They have some quite good material, including a whole playlist on programming and wiring a star-delta starter.

[@azharvoice440]

Awesome... Excellent work❤

[@realpars]

Thank you so much!

[@nimbo9492]

Hi, i am not an electrician, but isn't relay essentially a circuit breaker? Contactors, as far as i have read, works similarly to circuit breakers/relays, but rather they are "switching devices" and not used as overload protection devices (circuit breakers). Please corect me if any mistakes, just a confused human being 😄

[@nimbo9492]

And also, when a VFD is used to run an AC motor, is a contactor still needed? I thaught that maybe VFDs have contactors internally embedded.

[@realpars]

@@nimbo9492 In this instance, a contactor is not needed, and typically, not used.

[@realpars]

You are correct. Contactors provide a safe and protected way to switch power on and off "across the line" to 2 & 3-phase motors and other electrical loads (heaters, etc.).

[@MarioLopez-nh7vm]

Thanks