Thanks for the reply. I apologise for basic electronic knowledge. So what you are saying is that the Maximum Input Current of the relay is really the current that the relay requires to work ie 20mA? The fact that the Arduino can produce up to 40mA is irrelevant as it will supply what the relay requires? It will not damage the relay?
In addition, I have read that I can directly connect the Solid State Relay (SSR) to the Arduino digital output pin?
Really appreciate your help.
Yes. A load, such as the coil of the relay, "pulls" a certain amount of current. If the load pulled over 40mA, you risk damaging the Arduino, not the relay. The coils in the relay can also only accept a certain amount of current before it fails as well, but the current it "pulls" depends on the voltage applied across it.
You shouldn't have an issue connecting the relay straight to a digital pin if it only pulls a maximum of 20mA.