I am using multiple Songle relays on the ubiquitous 4 channel relay boards to switch line voltage light strings. I want to switch them on and off quickly but do not want to burn out the relays.
On the data sheet below it says
Max. ON/OFF Switching
Mechanically - 300 operation/min
Electrically - 30 operation/min
What does that mean? Can I switch it 300 times a minute or 30 times a minute?
What your looking at is it max operations for its highest rating.
Perhaps if switched quickly at high currents the contacts would burn out fast - without a link to the real datasheet I can't be sure.
You'd be better off using logic-level power MOSFETs for this sort of job - they can switch extremely fast and there are no contacts to burn
regards
Allan.
allanhurst:
You'd be better off using logic-level power MOSFETs for this sort of job - they can switch extremely fast and there are no contacts to burn
OP is switching mains power.
Relays can switch relatively fast. 10x per second shouldn't be a problem.
But contacts bounce and arc when switching a load. That will heat up the contacts.
I think that's why they give those safe operating times.
I would hesitate using 4-channel relay boards with songle relays for mains power.
Leo..
Wawa:
OP is switching mains power.Relays can switch relatively fast. 10x per second shouldn't be a problem.
10x per second would be good for my needs. Switching strings of 9.2 watt LED bulbs on and off in patterns. I want to switch them quick.
Wawa:
But contacts bounce and arc when switching a load. That will heat up the contacts.
I think that's why they give those safe operating times.
That is my question. What do those times mean? Do they mean 30 x per minute (once every 2 seconds) or do they mean 300 x a minute (5 times a second)?
I would be happy with 4 times a second that would give me 250ms pulses.
Wawa:
I would hesitate using 4-channel relay boards with songle relays for mains power.
Leo..
I understand but have used the boards in multiple projects in continuous use for multiple months. They seam to work. It is only about 30 watts per relay. The relays say they can handle 10 amps. I have 20 relays, each with 3 bulbs attached.
allanhurst:
- without a link to the real datasheet I can't be sure.
Is that not a link to the real data sheet? I attached the pdf.
songlesrdrelay.pdf (91.6 KB)
Lukinio:
I understand but have used the boards in multiple projects in continuous use for multiple months. They seam to work. It is only about 30 watts per relay. I have 20 relays each with 3 bulbs attached.
It's the isolation I would be worrying about, not endurance.
Look at the tracks on the board. I think there has to be 8mm clearance between low voltage and mains on 230volt. And the coil<>contact isolation has to be 4kV.
You do ofcourse use a separate 5volt supply powering the relay board, with JD-VCC jumper removed.
And have the Arduino connected to VCC and relay inputs only.
No connection between Arduino ground and relay ground.
That way you will have an extra layer of (opto) isolation.
Leo..
Sorry - missed the line-level bit... MOSFETs would be no good!
You could always use small SSRs - opto input, fast ( well, up to 100Hz because of the triacs which only turn off at a zero crossing) and excellent isolation.....
regards
Allan.
It will switch 10 times a sec at around 1 amp you'd be good
Hi,
If you need to switch any relay faster than 2Hz, forget it, it may not be the contacts that suffer but you have fatigue in the mechanical parts of the relay.
If you are switching AC, use a SSR, no brainer.
If you are using mains powered LED lamps, that is direct mains to the lamp, have you checked that the lamp is happy with pulsing the mains?
The lamp will have a SMPS built into its base and may not respond to pulsing supply.
Thanks.. Tom... 
A picture of the LED lamp would help.
Yea, relays aren't designed to be switched so often! You can use SSR, but those are rather pricey.
You could try giving something like this a try:
For isolation, you could use an optoinsulator, switching the gate of the mosfet! Are you switching 120 or 230/240 volts?
I can imagine this approach would be cheaper.
(However, I am not very experienced with mains connected circuitry, so please wait for others to confirm my claims before you build this contraption :D).
The noise of a relay clattering away would annoy me. Incidentally, I use exactly one of these relay modules which I got from an Ebay retailer as a buzzer, driven at 50Hz by the tone library. I could not use the relay for it proper purpose because the contact resistance was too high, it was probably a reject, but as a buzzer it great.
Wawa:
You do ofcourse use a separate 5volt supply powering the relay board, with JD-VCC jumper removed.
And have the Arduino connected to VCC and relay inputs only.
No connection between Arduino ground and relay ground.
That way you will have an extra layer of (opto) isolation.
Yes I have them hooked up just like this.
TomGeorge:
If you need to switch any relay faster than 2Hz, forget it, it may not be the contacts that suffer but you have fatigue in the mechanical parts of the relay.
I have the system set up switching at times in 500ms pulses, so 500ms ON / 500ms Off is that 1 cycle so 1Hz or is that already two switches so 2HZ?
It says that it can switch 10,000,000 times but that would be over in a couple months at that rate.
TomGeorge:
If you are switching AC, use a SSR, no brainer.
It seems that I bought the wrong equipment for this project. The reason I get these relay boards is because of the 10 AMP rating. The only SSR boards I have foudn have much lower current limits. I will look around.
TomGeorge:
If you are using mains powered LED lamps, that is direct mains to the lamp, have you checked that the lamp is happy with pulsing the mains?The lamp will have a SMPS built into its base and may not respond to pulsing supply.
I just figured that would be ok but now will see if I can find a picture of the bulb.
thegoodhen:
Yea, relays aren't designed to be switched so often! You can use SSR, but those are rather pricey.
That seems to be the consensus. Thanks for confirming.
be80be:
It will switch 10 times a sec at around 1 amp you'd be good
I assume you are talking about the SSR. I will investigate. Thanks.
I would offer that you should buy some relays and try them out.
But, I think we are in the middle of an X/Y problem thread.
Post a link to what you want to control, as much detail on the product and let us offer the best way to control it.
I just figured that would be ok but now will see if I can find a picture of the bulb.
bulb ? is this one that has a remote ?
6v6gt:
The noise of a relay clattering away would annoy me. Incidentally, I use exactly one of these relay modules which I got from an Ebay retailer as a buzzer, driven at 50Hz by the tone library. I could not use the relay for it proper purpose because the contact resistance was too high, it was probably a reject, but as a buzzer it great.
I ran the power for the coil into the NC contact
then when power was appplied,
it opened, removing power
then closed, applying power.
a simple 60 cycle buzzer.
however,.... I was trying to connect power to the NO side, so that with a button press, the coil would energize, then be self powered.
bottom line, I created a buzzer but had to re-wire to get what I was after.
I have posted an image on this thread, but on my laptop, it looks broken. Not sure what the deal with that is, but I am posting a direct link to the site I took it from:
It's a way to switch high current AC.
dave-in-nj:
I would offer that you should buy some relays and try them out.But, I think we are in the middle of an X/Y problem thread.
Post a link to what you want to control, as much detail on the product and let us offer the best way to control it.
bulb ? is this one that has a remote ?
The bulb does not have a remote. Here is a link to the bulbs that I am using. Each relay as a string of 3 bulbs.
Each bulb uses 9.5 watts so it is 28.5 watts per relay about .24 Amps.
EcoSmart-60W-Equivalent-Soft-White-A19-Basic-Non-Dimmable-LED-Light-Bulb
I attached an image of my current setup with the blue Songle relay boards.
thegoodhen:
I have posted an image on this thread, but on my laptop, it looks broken. Not sure what the deal with that is, but I am posting a direct link to the site I took it from:It's a way to switch high current AC.
first, go back and edit your post. bottom right is the edit buton.
you might have to choose modify
attach the picture., save the post ( attach is at the bottom left of your post)
modify again
copy the url of the picture on your post.
insert a picture ( top menu above your post), use your copied url.
remember, once you attach your picture, it has a hard location that has a specifc url.
the picture insert at the top menu bar has to use a fixed link. anything on your laptop is only a temporary link.
Dear Lukinio!
I know, it is an old topik, but I faced the same issue! Maybe it is usefull for others.
This relay CAN NOT operate at that speed.
I tried at 100 ms on-off with 230 V ac, but it made extreme prell. 10-15 switches at 100 ms. 
At 200 ms it worked, but sometimes did double swiches. Unstable.
I think, mechanicalli the max is 200 ms for on-off cycle. But still issues. I will try at 2000 ms (2 secs.) what is the electrical limit. ???
