Hello I'm trying to controle a SSR relay (3 phase 40A) that is turning a heating component in a water tank for beer making. I'm using a arduino MKR 1010.
When I plug the 5V pin of the arduino to the + of the SSR and the - of the SSR to GRD, the SSR led turns on and the heating element as well. When I plug it to the arduino Pin 6 and use a simpel blink code (copied down below) The led of the SSR turns on BUT at a lower brightness and the heanting element doesnt work.
The relay signal is suposed to be between 3 and 32 volts so I don't understand.
When Pin 6 is High it should triger the relay, as the 5V pin does?
I join picture of the SSR, picture of the arduino pluged on Pin 6 =>GND and plug on 5V=>GND
Thank you for your help !!
void setup() {
pinMode(6, OUTPUT);
}
// the loop function runs over and over again forever
void loop() {
digitalWrite(6, HIGH);
delay(10000);
digitalWrite(6, LOW);
delay(1000);
}
Hi,
If you use your DMM you will find that the output of the MKR is probably 3V3 or lower.
Measure the voltage across the input of the SSR with the MKR connected.
Can you please post data/specs on the SSR?
You may need to put a BJT in the circuit to switch 5V to the SSR instead of 3V3.
The spec 3 to 32volts, is only a spec, not written in stone.
The MKR output looks to me to be definitely to low for reliable operation.
Also the MKR can only supply 7mA on its pins without damaging it, what is the input current spec of the SSR at 3V?
The SSR is a 40A 3x220v so something quite big. The heating element tanks 22A max.
Do you think it's safe to only use a BJT to switch ON/OFF a 5v current that I would take from the arduino, or I should get an external 5v (or higher) curent?
Yohann, TomGeorge is right. The MKR output is only 7mA, which is barely enough to light the LED inside the SSR to turn on its output. You'll need to supply a little more current. I'd use a simple NPN transistor to control a 5V signal to the SSR for that task.
It looks like you need 15 to 20mA on the input of that SSR
Where did you purchase this SSR, most nondescript components like this are usually below spec when you finally get to test one.
The 5V supply from the controller should be enough, what you do is get the controller to switch the BJT or MOSFET ON, the BJT or MOSFET will then provide the current from the 5V supply to the SSR input.
I think you connect the 5V supply through a 220R or 330R resistor to the SSR's positive control input, and switch the negative control input through an NPN to ground. Switching the high side is more complicated.
