24V AC solenoid valve circuit with overload protection

Thread Starter

coco55

Joined Oct 7, 2021
4
Hello there,

I would like to protect triac circuit from overload in case the valve gets bad.
The 24V AC valve draws 1A so what's the best way to cut power off in case of sudden amps increase?
Let's say 1.5A threshold that can be adjusted with a resistor. Using Arduino I would like to reset the circuit.
Is there anyone who can help me with the circuit please?

Thanks!
 

ronsimpson

Joined Oct 7, 2019
1,630
poly fuse
This is a fuse that resets after a little time. I did not see one right for you on this page but it is a place to start.
Example: there is a fuse on that page that will hole at 1.1A, trips at 2A but should not be used above 12V.
It takes maybe 30 seconds for the part to reset and work again.
 

MaxHeadRoom

Joined Jul 18, 2013
23,906
I would like to protect triac circuit from overload in case the valve gets bad.
The 24V AC valve draws 1A so what's the best way to cut power off in case of sudden amps increase?
Your better option, if available is to use a DC solenoid valve, i.e. no surge current, the AC variety has very high inrush which continues until armature has completely shifted over.
 

Thread Starter

coco55

Joined Oct 7, 2021
4
poly fuse
This is a fuse that resets after a little time. I did not see one right for you on this page but it is a place to start.
Example: there is a fuse on that page that will hole at 1.1A, trips at 2A but should not be used above 12V.
It takes maybe 30 seconds for the part to reset and work again.
Thanks for the advice! The fuse is not an option. I need to control reset with arduino.....
 

Thread Starter

coco55

Joined Oct 7, 2021
4
Your better option, if available is to use a DC solenoid valve, i.e. no surge current, the AC variety has very high inrush which continues until armature has completely shifted over.
Thank you Max, AC valves are used everywhere in sprinkler systems so that's why I want to use AC valve. I will use varistor to eliminate the spikes but I still need current protection....
 

MaxHeadRoom

Joined Jul 18, 2013
23,906
Thank you Max, AC valves are used everywhere in sprinkler systems so that's why I want to use AC valve. I will use varistor to eliminate the spikes but I still need current protection....
There are equally as many 24vdc valves that are equal in action as the ac variety, you only see one's labeled AC for sprinklers because the majority of irrigation systems use AC.
But in a custom application it is your choice, mine would be DC, hands down.
If you have a 24vac supply, all you need is a bridge added for DC.
 

Reloadron

Joined Jan 15, 2015
6,204
If you are set on using a 24 VAC solenoid and want to measure the AC current to the coil and do something when the current exceeds a preset level using an Arduino UNO or similar uC you want to start with a simple Google of "ACS712 Arduino" should get you started. Here is one such example. Note in the link where the author mentions " Please be careful when choosing the ACS712, don’t try to play it safe like I did (by purchasing a 30Amps version), this will just give big fluctuation when you try to use it for a domestic use or small amps applications, so here for me a 5A or 10A version would have been fine. Also note that 30A or 20A … will affect your calibrations too, but it’s explained how to calibrate in video and in codes comments". You only really need a 5 Amp max current version. I also suggest you read and understand the ACS712 data sheet or data sheet of any sensor you choose to use. Additionally I assume you can read and understand the code so you can modify it for your intended application. Here are a few examples of ACS712 5 Amp modules.

That said personally I would likely go with a DC solenoid but as you mention AC and you mention Arduino I would start as I mentioned above using an ACS712 or similar sensor (it works fine on AC or DC).

Ron
 

MaxHeadRoom

Joined Jul 18, 2013
23,906
I would like to protect triac circuit from overload in case the valve gets bad.
N.A. has been slow in adopting DC voltage for solenoid valve applications, although in recent years it has improved.
One issue is that if for some reason the AC operated armature does not shift completely, the current goes way up.
By the time you develop a circuit to monitor the events on an AC valve, it probably would be quicker and easier to use a DC version where you do not see these anomalies.
 

Thread Starter

coco55

Joined Oct 7, 2021
4
If you are set on using a 24 VAC solenoid and want to measure the AC current to the coil and do something when the current exceeds a preset level using an Arduino UNO or similar uC you want to start with a simple Google of "ACS712 Arduino" should get you started. Here is one such example. Note in the link where the author mentions " Please be careful when choosing the ACS712, don’t try to play it safe like I did (by purchasing a 30Amps version), this will just give big fluctuation when you try to use it for a domestic use or small amps applications, so here for me a 5A or 10A version would have been fine. Also note that 30A or 20A … will affect your calibrations too, but it’s explained how to calibrate in video and in codes comments". You only really need a 5 Amp max current version. I also suggest you read and understand the ACS712 data sheet or data sheet of any sensor you choose to use. Additionally I assume you can read and understand the code so you can modify it for your intended application. Here are a few examples of ACS712 5 Amp modules.

That said personally I would likely go with a DC solenoid but as you mention AC and you mention Arduino I would start as I mentioned above using an ACS712 or similar sensor (it works fine on AC or DC).

Ron
Thanks Ron, actually I was investigating AC711 and 712. I have to find out how to implement in my code....Thanks for the link!
 
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