Hi,
I am trying to run a 240V AC Fan with a 40A AC rated SSR .. The control signal for SSR is directly from arduino GPIO.
It ran fine couple of times. Then my LCD started showing garbage characters whenever there was a button press but was still able to turn SSR on and off... a few times later it completely goes gaga when i press a button to turn on the SSR. It completely freezes and doesnt turn the SSR on.
Now, I thought SSR isolation could protect my Arduino from any back-EMF or spikes. Does AC fan generate back-EMF large enough to cross-over a SSR and fry GPIO? Or is it really the same AC line that may have let the EMF enter arduino through the power source?
Any precaution i should take before running AC inductive loads like motor/Fans with arduino+SSR?
Do you have a schematic of your setup?
What SSR were you using and how was everything wired up?
nothing special in terms of wiring.
SDA, SCL, VCC, GND to LCD
GPIO 8 and GND to SSR
GPIO 6 to pushbutton pulled up high with 2k2 resistor, grounded on button press.
tinman13kup:
What SSR were you using and how was everything wired up?
SSR is FOTEK SSR-40 DA (Taiwan made)
I would guess it's NOT the SSR. If you disconnect the SSR from the Arduino, are you still seeing garbage? Or, how about if you disconnect the AC from the SSR?
You can also try controlling the SSR with a battery or separate power supply. If it still interferes with your Arduino, there's noise getting into the Arduino through the power line and the Arduino's power supply.
Some SSRs don't have a current limiting resistor on the LED (so you can select a resistor for whatever voltage you are using). If you forget to add a resistor you'll draw excess current and that can "cause problems" (including frying the Arduino and/or the SSR). But, I've only seen "smaller" SSRs made that way and I don't know if they make 40A relays without a resistor.
A quick search just says it's discontinued and 7.5mA/12V input.
What does the SSR say on it?
DVDdoug:
I would guess it's NOT the SSR. If you disconnect the SSR from the Arduino, are you still seeing garbage? Or, how about if you disconnect the AC from the SSR?
Right now as the Arduino is fried, yes garbage coming on every button press, even while connected to laptop through usb and disconnected from AC.
DVDdoug:
You can also try controlling the SSR with a battery or separate power supply. If it still interferes with your Arduino, there's noise getting into the Arduino through the power line and the Arduino's power supply.
How do I filter power line noises? I am connecting a 12V smps to the arduino Raw and was hoping the regulator will filter out most noises though cutting off peaks!
DVDdoug:
Some SSRs don't have a current limiting resistor on the LED (so you can select a resistor for whatever voltage you are using). If you forget to add a resistor you'll draw excess current and that can "cause problems" (including frying the Arduino and/or the SSR). But, I've only seen "smaller" SSRs made that way and I don't know if they make 40A relays without a resistor.
Measured the current draw by SSR. its roughly 2-3mA. don't think its due to that. Any other precautions you can think of?
Hi,
Can you please post a copy of your circuit, in CAD or a picture of a hand drawn circuit in jpg, png?
Can you please post a picture of your project so we can see component layout?
Thanks... Tom... 
TomGeorge:
Hi,
Can you please post a copy of your circuit, in CAD or a picture of a hand drawn circuit in jpg, png?
Can you please post a picture of your project so we can see component layout?
Thanks... Tom...
Hi Tom,
here is what i could draw up...
Hi,
Have you programmed your UNO with anothert working code, to see if all is well?
Try Blink Without Delay from the Examples folder.
The fact that the LCD is showing garbage, usually indicate a bad connection or incorrectly wired LCD display.
Thanks.. Tom..
I have done so already.. The arduino works fine when I let it run on its own and not using those pins... even in my actual sketch there is a lot of initial data printed on LCD. Arduino runs through all that fine.. only shows garbage on lcd and doesnt activate the SSR when i press the button to activate the SSR. Even its giving Serial output to serial monitors fine.. connections etc are tight.. most of it is soldered!
Do you think its safer to put a LC filter before RAW input of arduino to filter any AC noise seeping in or does it adversely affect arduino?
