jackintosh11 wrote:Can cars designed for 25Hz run on 60Hz? If so, why not just convert the power from DC to NY?
Yes, they can. The M2's ran when the New Haven Line was 25 Hz, then 60 Hz after the 1984 changeover. NJT's Arrows can run on either. The original transformers they came with had the tolerances to do that. The problem is they can't transition between different frequencies or voltage on-the-fly automatically without carrying the extra transformer core. This is why NJT has the segregation of some Arrows to 60 Hz/25 kV territory and some to 25 Hz/12.5 kV territory. Same vehicles, same transformers...but the cars can only roam inside one frequency.
New EMU's have the capability to transition. SEPTA Silverliner V's can do 25 Hz/12.5 kV, 60 Hz/12.5 kV, and 60 Hz/25 kV as future-proofing should SEPTA start gradually changing its voltages. I don't know if they've been tested on all 3, but theoretically you could run any SLV trainset from Philly to Boston. Whenever NJT does its Arrow replacements and SEPTA replaces the Silverliner IV's, they'll likewise be compatible with all 3 types of overhead. M8's have the 60 Hz/12.5 kV and 60 Hz/25 kV cores for roaming in SLE territory, as well as the traditional automatic change to 750 V DC third rail. They could have been ordered equipped with the 25 Hz core as well but that would've been incredibly expensive and add more maintenance overhead for a frequency that isn't used anywhere in MNRR territory, and the cars were already overweight beforehand.
It'll be way less expensive for them to just install the extra 3rd rail out to the phase break for enabling Penn service. If there were ever a need to run into New Jersey on MNRR equipment (there isn't, no matter how many times it's brought up here, and crew qualifications inhibit that), the North River Tunnels have 3rd rail to the portals. A dual mode locomotive configured for over- or under-running 3rd rail can take a push-pull set the whole distance and fire up the engine at the portal. Same as they do at GCT today, same as Amtrak does on the Empire, same as MNRR will do for Hudson-Penn service. Ditto for any unforeseen reason to run-thru to LIRR; dual-mode if it's stopping at Penn, or straight diesel if it's skipping Penn from New Haven. The only technical requirement there is having a cab signal unit that can read LIRR's 2 extra aspects and having the requisite--and unlikely--crew qualifications in both territories.
That relatively inexpensive bit of 3rd rail extension on the Hell Gate Line is the only thing that's needed for Penn operation, and push-pull options could feasibly cover any other real, special event, or imaginary service patterns without new construction. So there's no reason to equip 25 Hz-capable EMU's at such extreme weight penalty when no feasible routing is prevented. You're not going to New Jersey on a Game Day or Shopper's special making all local stops on an EMU; pretty much any run-thru option is going to be an express that requires the maximal seating capacity that a push-pull provides. And Metro North to Secaucus Loop is not bloody going to happen, not even when Gateway is built; there just isn't enough tunnel capacity to run everything thru to everywhere.
