Hello everyone, I am trying to google around, but I cannot find any relevant information about it... I am experiencing pretty much the same issue described in this other thread Relay switch stuck in one state - Project Guidance - Arduino Forum with the difference that I am wiring some LED reflectors to light up my back yard, and I am not wiring them to the "always on" connector in the relay, so I need to switch the relay on, in order for the LED reflectors to turn on.
I am wiring it using the optocoupler, and everything works just fine, since I can switch each relay on and off just fine, however the Relay that drives the LED reflectors, stayed on, even that the SMD LED turned off in the relay module, as if the coil would just remain stuck...
I applied the "percussive maintenance" as suggested in that other post (ie. I flicked it) and it indeed released and the reflectors turned off...
Now, I am not getting anywhere near the max current these relays are supposed to support, which is 10A for 250V... could they be such a piece of chinese garbage that they are not reliable at all?
does anyone have a suggestion on what to do? (I would prefer not to use SSD relays, btw)
Mmm... so I should not buy these relay modules? is there some way around it? I've read some information on using varistors, or a snubber, but it appears those solutions are more appropriate for very high loads, and not for my application which is about 10% of the load the relay should be able to withstand...
As per the schematic, is there some online tool I can use to create it? But just to be clear, the arduino and the relays work fine, I can switch each of them on and off without an issue, the only problem is one of them remaining "stuck" when trying to switch it off
Wawa:
Did you look at the inrush current of those lights, because that's what the relays are switching.
I have not... how can I do that?
Wawa:
Why not SSR. They come in the same 4-relay configuration,
and they don't need a separate 5volt supply (which you should have now).
Leo..
Yeah, I experimented with SSR before, but I've noticed issues with LED lights where they occasionally would flicker when on, so I thought using normal relays would be much more "stable"... plus I wanted to build in the future another device where I would sense the room temperature and switch a heater on and off... but if these things are so unreliable, I don't think I want to mess with that...
Just to give you more information... the relay wouldn't always stuck... so far it has only happened once... After I flicked it and it released the contact, I tried turning on and off the same lights, and it worked as expected... several times... I think it remained stuck after it was in the "on" position for a while...
On relays 1 and 2, I have 10W LED bulbs... those work just fine. Relay 3 has the 3 LED reflectors. Those are summing up 150W, and this is the one that got stuck. Relay 4 is not used
Did you try to make the relay operate manually? Hook relay up to power, hook switching pin to low/high, does it click, does the relay contact switch? Does relay 4 work in place of 3?
The relay works perfectly... I can switch on/off each and every one of the 4 relays...
The issue is that on Relay 3, which has the 3 LED reflectors, I had it in on for about 1 hour... when I tried to turn it off, I could see the small SMD LED in the relay module turning off and I could hear a very soft "click" but the physical connection wouldn't be separated. I had to physically give it a "flick" with my finger in order to the contact to be actually released.
I am just trying to find if these relays are just garbage that cannot be trusted, and if anyone else has experienced something similar... And if so, if there's some workaround, besides buying better relays and build a circuit myself, instead of the already built module
Idahowalker:
nothing more to try to figure out, relay broke. use a new one. cheap, you know what you bought, what you paid, and how they are working, you decide.
Yeah, well, almost everything in Arduino world is cheap, so I was just assuming the relays would just work... Now the question is... did I had bad luck? or are these modules 100% unreliable?
frapell:
Yeah, well, almost everything in Arduino world is cheap, so I was just assuming the relays would just work... Now the question is... did I had bad luck? or are these modules 100% unreliable?
They are reliable enough when run within their ACTUAL ratings rather than the ratings you assumed. As I said earlier, DC and AC are very different when it comes to relay contacts. DC arcs do not quench and will try to wled the contacts together.
AJLElectronics:
They are reliable enough when run within their ACTUAL ratings rather than the ratings you assumed. As I said earlier, DC and AC are very different when it comes to relay contacts. DC arcs do not quench and will try to wled the contacts together.
Sorry for not being clear enough... these are LED reflectors rated at 220v - 50W each, so that's 150W total, which should be about ~0,68 A that's 10 times less than what the relay is rated for... Am I correct?
You are correct but that’s operating current. Inrush current at turn on is typically much higher for a device with a switch mode power supply. There is a capacitor to charge and that requires current. It’s the turn on current that causes contact damage/pitting/welding.
Your schematic doesn’t appear so we don’t know if you have one lamp per relay or if the three lamps are controlled by only one relay. That would be useful information.
How many total relay failures have you had? If it is only one, try a new relay. One failure can happen. It’s when it occurs more than once you know there is a design problem. With what has been posted, I’m not sure I know where you are in that process.
It just might be a simple case of needing a relay with a higher power rating. There are inexpensive 30 amp power relays available in module form that may be more suitable for the application.
WattsThat:
You are correct but that’s operating current. Inrush current at turn on is typically much higher for a device with a switch mode power supply. There is a capacitor to charge and that requires current. It’s the turn on current that causes contact damage/pitting/welding.
So, the relays are rated at 10A, and the operating current should be around 0.7A for 3 LED reflectors... could it be that the inrush current is over 14 times the operating current? I don't think I can measure this with a regular multimeter... any suggestion on the cheapest hardware I could get to measure the inrush current accurately?
WattsThat:
Your schematic doesn’t appear so we don’t know if you have one lamp per relay or if the three lamps are controlled by only one relay. That would be useful information.
yes, my schematic does show it. the 3 LED reflectors are controlled by 1 Relay.
WattsThat:
How many total relay failures have you had? If it is only one, try a new relay. One failure can happen. It’s when it occurs more than once you know there is a design problem. With what has been posted, I’m not sure I know where you are in that process.
Yeah, I've only seen it once... after it happened, I tried it several times... on and off, on and off, and so on, it didn't got stuck even once... but I am trying to build some home automating solutions around my house, and the whole idea is to be more energy efficient, so having a relay stuck with reflectors draining 150W without me noticing, doesn't sound like a good solution to me Trying to build something bullet proof, and i guess I'm finding some limitations...
WattsThat:
It just might be a simple case of needing a relay with a higher power rating. There are inexpensive 30 amp power relays available in module form that may be more suitable for the application.
I didn't see any information about how you power the relay coils.
Slow reacting relays (not enough power) could also lead to problems.
Larger relays draw more coil current...
Don't understand your fear for SSR.
Modules with G3Mb-202P (zero-crossing) SSRs work just fine.
Leo..
Wawa:
I didn't see any information about how you power the relay coils.
I have a small power supply unit that converts 220v AC into 5V DC, with 700 mA max. (This) I split this +5v in 2, and supply current to the RAW pin in the Arduino, and also supply it to the JD-VCC input in the relay module
Do you think I should use 1 exclusively with the Arduino and another one only for the Relay module? Each relay needs about 70mA for the coil, so I believe this PSU should be more than enough for powering everything...
Wawa:
Slow reacting relays (not enough power) could also lead to problems.
Larger relays draw more coil current...
yeah... I have experimented several combinations, and found some cases were I would not be able to switch all of the relays on at the same time... however in my current setup, I can switch them all on, without much problems...
Now, could it be that a Relay would not open the circuit when it doesn't have enough power? I can imagine (and as I said before, I actually saw it) not closing because the coil would not have enough current, but I fail to see why it would be an issue when turning the relay off, ie. when the coil doesn't need power...
Wawa:
Don't understand your fear for SSR.
Modules with G3Mb-202P (zero-crossing) SSRs work just fine.
Leo..
It is not "fear", I am actually replacing SSRs with these non-SSR, because some of the LED bulbs would occasionally flicker, and I thought the SSRs were to blame...
