hello guys this the flow chart for 3-Φ phase reversal detection.My question is why they use the logic

if captured time(T) in between 3 mesc and 8 msec ???
Is that for (3+8)/2 = 5.5 msec??

It is not clear to me.

In my country the frequency is 50Hz so what should i take??

 

The reason it is done this way is because they are measuring time between the first and third phase, which if the ritation gets reversed is then the time between the third and first phase. it took a bit to figure that out, but it makes perfect sense. Are you needing to duplicate the function, or just wondering. The technical description mentions 50 HZ and the different time setting, I think.