Hi all,
I bought a couple of these single channel solid state relays and am currently using one of them to run a 200W 240V AC load, but they seem to be running hot, not burning hot, just hot.
Now one has failed already and I just want to check if someone knows what might be causing it? They are rated for 2A, so my 200W load should fall well inside specs.
Any input would be appreciated.
Regards
Exactly which relays are they ???
cheers Bob
Sorry, thought the title was enough
1 Channel Solid State Relay Module (DC Control, AC Load) | Core Electronics Australia (core-electronics.com.au)
Hi Altus
Not quite. There are dozens of relays that would fit your description. Being as complete as possible saves time and confusion.
A bit of your problem could be the load and/or inrush current.
There is some pretty good info here
especially the section on usage hints. The info starts out about the actual relay and progresses to what seems like the unit you have.
How hot is hot. That is the term is pretty relative, what seems hot to you could be normal. Is it the relay itself hot or something else. A rough test is to spit on your finger and see if it boils and quickly dries when applied to the device. Usually if you can put your finger on a component without burning it is probably OK.
You say one unit failed. Did the relay itself fail or something to do with the driver circuitry. The above site includes circuits which seem to be of your device but only mentions generic Chinese Manufacturers. The info provided on the Core web site is pretty basic at best.
A circuit showing how you are driving rhis device would help if possible.
Cheers Bob
Hey Altus,
I hope youâve got a licensed electrician helping you out! Mains voltage can kill, and you need to be licensed to work on it.
Those relays arenât certified for 240v usage in Aus. The relay itself has certification for mains voltage in other countries so itâs technically capable, but the PCB itâs mounted to isnât.
If you need to switch LV to an appliance, youâre much better off doing aomething like this:
Sorry, slipped up on that.
Just assumed that the board the relay is mounted on would be rated the same as the relay. BUT I forgot it is Chinese.
The data sheet for that relay does say 100 to 240VAC. Omron is a well known brand of relays and other equipment in Australia (I have used them for many years, particularly the LY series. Very reliable) and I am surprised that it would not be certified for use here, but you are probably right about the board.
Cheers Bob
Ah, I didnât read this closely enough. I saw single channel relay and thought it was this one:
Sorry, just changed countries. A bit jet lagged at the moment!
Iâd have to check the datasheet for the Omron one, it may well have Australian certifications. But the point about the PCB itâs mounted on still stands - itâs probably technically capable, but you need the certification for the whole product (which includes the PCB).
In fact, it looks like the relay pictured has actually been discontinued by Omron, so @Altus152324 or one of the Core staff may need to confirm the actual relay on the product.
Hi All,
Awesome discussion, I can confirm the relay onboard is the G3MB-202P 30Y4E
@Bryce covered the 8 channel board here:
And features the same relay @Oliver33 linked.
Liam.
Hmm, did you mean to fill this out later?
Hi Oliver,
Yeah, Iâve updated the reply 
Liam.
Ok, so another one died this morning, so I assume it has to do with the inrush current.
Clearly the inrush current of my LED lamps are just much higher that the standard lamps, so think I am just going to revert back to running contactors, likely very overkill, but who cares, they have not let me down in the past.
Oh, forgot to mention, it is a very simple circuit, using a raspberry pi to control a RAMPs board to control my farmbot, the RAMPs board provides a signal to the relay board to run my grow lights, which is in turn controlled by the pi running a lighting schedule.
Hi Altus
The LEDs themselves would have far less inrush current than incandescent lamps which have a very low cold resistance.
If you are powering your LEDs with switch mode power supplies it is the power supplies that have the inrush problem charging up all the quite large capacitors. For instance I have a 5V 14A (70W) MeanWell supply powering some LED strips which allowing for efficiency losses should draw something like 350mA to 400mA @ 240VAC, yet the inrush current is quoted as up to 40A. Probably in practise not that high but they may allow a bit of âfudgeâ factor. You can see the magnitude of this though and must be considered. Even the humble electric motor will have an inrush current (from standstill) of 7 to 10 times its running current.
Cheers Bob
PS. I would urge you to read that article I linked earlier. One statement in the first paragraph reads.
âHowever, I would like to point out at first that SSRs are not suitable for all projects, and you must use them with extreme careâ.
Hey Bob,
Did have a read, this was the first time I used SSRâs for 240V AC, have used them on low voltage projects before and thought I might just as well give them a try, you know, for shits and giggles, and the fact that I had a couple on hand also swayed me 
These are the lights in question Mars Hydro TS 600 LED Grow Light | Best for Indoor Growing Australia | Sale 2021 â HomeGrow
unfortunately they do not mention inrush current or any other helpful info.
Oh yes, the âhotâ I was referring to, was it was hot to the touch, but would not burn my finger at least. So I recon less than 50C
Gonna just replace them with contactors, but will use a timer switch in the meantime.
As I said LEDs donât have âinrushâ current. The switch mode power supply has.
Cheers Bob
Hi Altus
If you really want to use SSRs you could consider switching the DC supply to the LEDs and leaving any switch mode power supplies turned on.
You would have to use DC SSRs or âSwitch at any timeâ or âNON zero crossing switchingâ types.
Cheers Bob
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