Pnnto Action: Relates to Pantograph: that is the four armed or diamond armed levers with a flat aluminium-copper bed which touches the Overhead Wires (current lines) OHEs and collects current. This is drawn down to the transformers insider the electric locomotives and stepped down to operational voltage using thyristors (voltage converters), and then used to drive the electric motors. Panto Action means that.
It also means that when the train is approaching a section on the railway tracks where two feeders of electricity are being used, in order to prevent 'electrical collision", the panto is lowered - known as neutral section - till the engine crosses the 'neutral section - and then raises the pantograph to regain contact with the...
more... new feeder and start normal operations of drawing current and raising speeds..
The LPs and ALPs know the neutral sections in their working time table. If you want to see it yourself, you will find signboards mounted on the left hand side on a straight line showing a white board with signs 250 m, then 150 m, then 50 m, and then a sign which shows a perpendicular line, with an underline and again a perpendicular line Below THE UNDERLINE.. telling the LP lower pantograph.. After passing the neutral (sometimes called dead section in Railway terms), you will find three vertical lines aligned in same line on a white board again, telling the LP raise pantograph.
This also happens in sections where DC lines and AC lines converge.. Seen very normally in Mumbai area - this area is now under conversion to full AC and DC is being replaced.
Good wishes.