Since now I have these two diagrams now one thing is remaining,I now need to detect when a phase is missing or when one or two or none of the phases is present such that when someone presses the button to test the 3 phases are first checked if all are present if one is missing the test is terminated and a phase missing is displayed and the way am thinking about the way to go for this is now full wave. The Arduino side remains the same but the optocouplers side has to now detect both negative and positive so that for the other 3 Arduino pins on the other side if any pin is missing a HIGH that shows that a phase corresponding to that pin is missing. So question is now the diagrams for full wave now for both with neutral and without neutral . The Arduino side remains the same.