Hi, when switching between 2 non synchronised 240 V AC supplies, you need to turn off 1 switch and wait a second or 2 before closing onto the other supply, if you don't do it this way and swith AC as per your sketch, you will get a high resultant voltage that will blow your load.
You only need it long enough to ensure it's less than the frequency of the line voltage minus inductance. Most contactors are not fast enough to overpower like this where you have two simultaneous peaks. 50/60hz is typical so 1/50th of a second times two for two waveforms. Most contactors (except SSR or other MOSFET) are not fast enough because they're mechanical.
Bi-polar transistors aren't like mosfets. You need a current limiting resistor between the Arduino pin & the base otherwise what you effectively have is your output pin connected to ground through something equivalent to a diode junction & the micro controller will pump out as much current as it can. It probably has some current limiting there...maybe?...but it can't be good for it in the long run nevertheless. And speaking of diodes, where are the back EMF cancelling diodes on those contractor coils? You never know when that "lucky" spike will come that will zap your transistor or even worse, your Arduino in the process.
Hi Xanataph! You're definitely right that it really should have resistors on the base. Looking at the project, I'd put aside 2 x 1k resistors for that purpose! I think I'd forgotten to put them on. Regarding the back EMF, I'd not considered it! Thanks for your comment! :-)
Antony Cartwright what size power transistor did you use and what would you recommend about the back voltage and the resistor before it reach the audrino
Old video but I'll comment anyway. I went down a path years ago using computer (ESP32, RPi, Linux PC) control but there is one big flaw. Sooner or later you have to reboot the computer. If you don't the computer could lock up or reboot itself. At that point, both contactors open and your load gets no power. You can wire those contactors to be sensitive to one or the other power being present and switch accordingly. I did it with the inverter being the priority by using the NC aux terminals. I then added an SSR to allow my computer to interrupt the switching; essentially delay the switch from mains back to inverter. The computer give the batteries enough time to recharge then closes the SSR. I'm counting amp-hours in vs out. If the PC fails the system stays on mains power. Btw, you also need mains coils in your contactors for that to work. For me in the US that's 110v coils.
hi Sir, pls. guide for - i have two 3KVA UPS with 6 batteries set in each, i want to make redundancy between these two UPS, i mean if one UPS is down, its load should move to 2nd UPS without any power down (my devices must run continue) . pls. advice me sir, pls. reply
It can be also digital output but the initial output voltage of the microcontroller must be 5v, for analogWrite(xyz,255); gives exact 5v and digital write function also provides 5v
Do you mean instead of the transistors? Or instead of the contactors? I wouldn't replace the transistors with relays because I think transistors are way better suited. About the contactors, I technically could replace those with relays, but it would lack protection. No mechanical interlock, and they can failed closed!!! That cannot be allowed to happen! :-)
SSRs are sold state devices and have no moving parts to fail closed. They dont need a transistor to drive them and can be driven directly from an Arduino digital pin. There are also SSRs that can handle up to 50 Amps. The only disadvantage I can see is that they dont have a mechanical interlock, but an electrical interlock could easily be implemented in the Arduino code ant this would always be more reliable than any mechanical interlock (no moving parts). I guess the other disadvantage would be that you would need 4 SSRs to provide complete switching of both live and neutral lines of both circuits.
@@Mr31Vince hi i am very interested in this suggestion you have made could you please send me more detailed info on how i would do this i want to build an ATS to switch between a 240v petrol generator and the mains 240v due to frequent mains power outages thanks in advance email: Martinhowarth30@yahoo.co.uk
You could do all of this with one contactor just using the normally open(13/14)/closed(21/22) pins and just need a switch for A1/2 voltage to exist or not. I presume the NO would be from solar and NC from grid power...
nope. those NC and NO terminals in the upper part are auxiliary. they are not rated for high Amps. Contactors by design are only NO. Just open one and see.
@@ArminYekkalam I opened one. There's a contact on the top in its rested state (NC) and one when it's closed (NO). The ones "on the top" are signal and power the magnet. 🤷♂ So as I initially stated, if the input signal from the contactor is grid power running the magnet, it could be in either NO or NC however you design it to work. I would have the magnet NOT powered when grid power is applied personally. Then when you lose grid power, it flips and activates the solar source circuit and disconnects the connection to grid so it won't backfeed. Not that complicated.
Hi. Im wondering if anyone can help. Im an electrician and have been for the past 10 years. However i never learned any of this stuff in college. What course would i need to take to learn this stuff. I currently do fire alarm system installations aswell so the closest i get to this type of stuff is with relays powering AOV for smoke extraction. Ive recently been asked about a ATS for a lift supply in the event that the mains supply faily then a generator would kick in. However i dont really know what im doing so had to turn down the request, but i would live to learn. Can anyone point me in the right direction. UA-cam is great for learning but a class is what i need due to questions that arise. Thanks
Hi, I didn't do a class for this either. I've never done any electronics class in my life. If you want to learn this, buy some second hand contactors and play around - safely!
@@Qam001 Sir, you can buy Arduino UNO (board with microcontroller good for starter) and download the Aruino IDE. This has sample basic codes and easy to learn.
you can but, you run into issues of the common ground, that is ok if you are controlling something stand alone but if you're joining something off grid to something on grid, I am not sure you want to be doing that for safety. ideally you want your load to be powered by isolated circuits, so you're either grid powered or off grid powered. your area might also have code requirements you'll need to follow depending on where you are. be safe
Hi, to make good contact, please heat wire thoroughly, tin the ends. Make sure that both surfaces are clean and free from oils before you apply solder.
![Дон ДОН, Алаудинов и СБЕЖАВШИЕ из под Курска ахматовцы 😁 [Пародия]](http://i.ytimg.com/vi/dEfCf5IK26Q/mqdefault.jpg)
Hi, when switching between 2 non synchronised 240 V AC supplies, you need to turn off 1 switch and wait a second or 2 before closing onto the other supply, if you don't do it this way and swith AC as per your sketch, you will get a high resultant voltage that will blow your load.
Hi! Thanks Ian! This has been wired up in this way for over a year now and nothing has blown yet! Maybe it will soon though, I don't know.
he is right, normally you need to use something to detect when AC is at 0v, and switch at that right moment
@@AntonyCartwright Doesn't matter, since your design is flawed. This isn't good at all you need to make a version two that is correct.
It would be a disaster to blow your load unintended.
You only need it long enough to ensure it's less than the frequency of the line voltage minus inductance. Most contactors are not fast enough to overpower like this where you have two simultaneous peaks. 50/60hz is typical so 1/50th of a second times two for two waveforms. Most contactors (except SSR or other MOSFET) are not fast enough because they're mechanical.
Bi-polar transistors aren't like mosfets. You need a current limiting resistor between the Arduino pin & the base otherwise what you effectively have is your output pin connected to ground through something equivalent to a diode junction & the micro controller will pump out as much current as it can. It probably has some current limiting there...maybe?...but it can't be good for it in the long run nevertheless.
And speaking of diodes, where are the back EMF cancelling diodes on those contractor coils? You never know when that "lucky" spike will come that will zap your transistor or even worse, your Arduino in the process.
Hi Xanataph! You're definitely right that it really should have resistors on the base. Looking at the project, I'd put aside 2 x 1k resistors for that purpose! I think I'd forgotten to put them on. Regarding the back EMF, I'd not considered it! Thanks for your comment! :-)
Antony Cartwright what size power transistor did you use and what would you recommend about the back voltage and the resistor before it reach the audrino
Nice video note though the NC contact will not become NO just open lol
Old video but I'll comment anyway. I went down a path years ago using computer (ESP32, RPi, Linux PC) control but there is one big flaw. Sooner or later you have to reboot the computer. If you don't the computer could lock up or reboot itself. At that point, both contactors open and your load gets no power. You can wire those contactors to be sensitive to one or the other power being present and switch accordingly. I did it with the inverter being the priority by using the NC aux terminals. I then added an SSR to allow my computer to interrupt the switching; essentially delay the switch from mains back to inverter. The computer give the batteries enough time to recharge then closes the SSR. I'm counting amp-hours in vs out. If the PC fails the system stays on mains power. Btw, you also need mains coils in your contactors for that to work. For me in the US that's 110v coils.
Can you share a part list?
Is this still the best way to make an automatic transfer switch? If not an update to this video would be a great idea :)
Use Timer relays. I try to avoid microcontrollers for this type of application
Good Zambia
can you give link of where to get this contactors?
thank you for that sharing sir.
No problems!
I have contactor having coil voltage of 220v can I trigger the coil input voltage with SSR (solid state relay) please reply 🙏
But how to me the générateur at automatical with 2 contacteur
hi Sir, pls. guide for - i have two 3KVA UPS with 6 batteries set in each, i want to make redundancy between these two UPS, i mean if one UPS is down, its load should move to 2nd UPS without any power down (my devices must run continue) . pls. advice me sir, pls. reply
Thx enteresting info.
Brilliant instructional video! well done
Hi Antony. Can i ask you a related question on a one way 240.flow contractor. Thanks
You can't connect an output directly to a transistor, you'll need a resistor on the base
Why must it be PWM output pins on the microcontroller and not DigitalOut pins
It can be also digital output but the initial output voltage of the microcontroller must be 5v, for analogWrite(xyz,255); gives exact 5v and digital write function also provides 5v
Why not use high current 240v SSRs (solid state relays) switched by 5v directly from Arduino digital output pins?
Do you mean instead of the transistors? Or instead of the contactors? I wouldn't replace the transistors with relays because I think transistors are way better suited. About the contactors, I technically could replace those with relays, but it would lack protection. No mechanical interlock, and they can failed closed!!! That cannot be allowed to happen! :-)
SSRs are sold state devices and have no moving parts to fail closed. They dont need a transistor to drive them and can be driven directly from an Arduino digital pin. There are also SSRs that can handle up to 50 Amps. The only disadvantage I can see is that they dont have a mechanical interlock, but an electrical interlock could easily be implemented in the Arduino code ant this would always be more reliable than any mechanical interlock (no moving parts). I guess the other disadvantage would be that you would need 4 SSRs to provide complete switching of both live and neutral lines of both circuits.
Vince Williams I'll look into this. Thanks for your comment!
@@Mr31Vince hi i am very interested in this suggestion you have made could you please send me more detailed info on how i would do this i want to build an ATS to switch between a 240v petrol generator and the mains 240v due to frequent mains power outages thanks in advance email: Martinhowarth30@yahoo.co.uk
You could do all of this with one contactor just using the normally open(13/14)/closed(21/22) pins and just need a switch for A1/2 voltage to exist or not. I presume the NO would be from solar and NC from grid power...
nope. those NC and NO terminals in the upper part are auxiliary. they are not rated for high Amps. Contactors by design are only NO. Just open one and see.
@@ArminYekkalam I opened one. There's a contact on the top in its rested state (NC) and one when it's closed (NO). The ones "on the top" are signal and power the magnet. 🤷♂
So as I initially stated, if the input signal from the contactor is grid power running the magnet, it could be in either NO or NC however you design it to work. I would have the magnet NOT powered when grid power is applied personally. Then when you lose grid power, it flips and activates the solar source circuit and disconnects the connection to grid so it won't backfeed. Not that complicated.
Hi. Im wondering if anyone can help. Im an electrician and have been for the past 10 years. However i never learned any of this stuff in college. What course would i need to take to learn this stuff. I currently do fire alarm system installations aswell so the closest i get to this type of stuff is with relays powering AOV for smoke extraction.
Ive recently been asked about a ATS for a lift supply in the event that the mains supply faily then a generator would kick in. However i dont really know what im doing so had to turn down the request, but i would live to learn. Can anyone point me in the right direction. UA-cam is great for learning but a class is what i need due to questions that arise. Thanks
Hi, I didn't do a class for this either. I've never done any electronics class in my life. If you want to learn this, buy some second hand contactors and play around - safely!
@@AntonyCartwright oh ok. Lol fair enough. I just thought there would be some kind of classes for it.
@@Qam001 Sir, you can buy Arduino UNO (board with microcontroller good for starter) and download the Aruino IDE. This has sample basic codes and easy to learn.
Yes
Where can I get the part # for the switch and the connection pin?
Hi love it
Where is the aduino code ?
Share info about the material used making the change over switch please
TIP41C
Merci pour votre produit
loukelec loukelec thanks...
Automatic change
Moffett would have been better also diodes for protecting the circuit if not built into the moffett
Thankhs sir
Hello, i want to controll a 380v motoro 1.5hp how can i do this ? what part to i ned?
Circuits
Are these contractors rated for AC or DC voltage?
Dc
Specified in datasheet
The schematic diagram and code
I think we can do ATS much simple than this, by only one contactor, using the No contacts, and Nc contacts also.
you can but, you run into issues of the common ground, that is ok if you are controlling something stand alone but if you're joining something off grid to something on grid, I am not sure you want to be doing that for safety. ideally you want your load to be powered by isolated circuits, so you're either grid powered or off grid powered. your area might also have code requirements you'll need to follow depending on where you are. be safe
@@saeedhossain6099 A 2NO/ 2NC contactor easily solves that problem by switching both live and neutral
Can I use 5v relays instead of the transistors
You would still need to drive the relay with a transistor, and a flayback diode. The i/o pins are not designed to sink that much current.
G
no req arduino
I want to have good contact with you sir
Hi, to make good contact, please heat wire thoroughly, tin the ends. Make sure that both surfaces are clean and free from oils before you apply solder.
Nice video but you could at least have cut your nails a bit shorter