Dear Charles,

Ankas tripped all of us with his subject of "Direction sensing " Looks like he wants to sense if the inverter is feeding the load (or) the line is feeding the inverter ! To me it appears a very odd way of wiring up an UPS or inverter - normally the line source is given to the input of the UPS and THAT decides whether it feeds the load or the incoming line feeds the load.

Anyway the link you posted appears intersting and an easy way to the find out the phase sequence. Thanks.

Raghu