I’m not an expert, but I think it has to do with AC vs DC electrification. With a DC third rail subway you can just feed it back into the lines no problem, but with AC you have to get the phase sync exactly correct or it will cause pretty serious problems. It’s the kind of thing that depends a lot on how old the system is, how energy distribution works, etc.
If there is an actual expert here I’d also like to know more…!
I’m not an expert, but I think it has to do with AC vs DC electrification. With a DC third rail subway you can just feed it back into the lines no problem, but with AC you have to get the phase sync exactly correct or it will cause pretty serious problems. It’s the kind of thing that depends a lot on how old the system is, how energy distribution works, etc.
If there is an actual expert here I’d also like to know more…!
That makes a lot of sense.