Performance under wire—different systems

Whether ALP44, ALP46, or Arrow III is there a noticeable difference in performance when running under: 11kV/25Hz (e.g. NEC, NJCL north), 12.5kV/60Hz (e.g. NJCL south), and 25kV/60Hz (M&E lines) ?

IIRC the section I am denoting NJCL south was or is to become M&E compatbile soon (i.e. 25kV/60Hz) .

There is no real difference, as in all cases the transformers on the equipment put out the same volts and amps regardless of the voltage flowing in. I believe the line voltage differences have mainly to do with power distribution.

Are the benefits of 25 kV really a big deal vs the 12 kV? I mean, was it really worth it to convert the other half of the NJCL to 25 kV? Now they are forced to only use push/pulls beyond South Amboy (or is it Matawan?)

Also, I would like to see them use some Arrows for the South Amboy Locals. I miss seeing the MUs on the NJCL. Plus, the only low level stops would be Perth and South Amboy so it wouldn't be much of a deal to have these units operate on these trains.

Nick11A wrote:Are the benefits of 25 kV really a big deal vs the 12 kV?

Half the substations IIRC...I remember reading that with the 25kV 60Hz system, you only need a substation every 20 miles.

Amtrak did themselves intend to convert the former PRR to 25kV 60Hz but never got the funding to do it.

Of course, the other side of the coin insofar as the MUs is that they could have been rebuilt with automatic variable-tap transformers to handle the voltage/frequency changes, back when they got their first rebuild which also should have included "long doors"...

Irish Chieftain wrote: Half the substations IIRC...I remember reading that with the 25kV 60Hz system, you only need a substation every 20 miles.

OK, that is at least one good benefit. But still, I question the decision to convert the NJCL at that time to 25 Kv. They should have waited to when the Arrows were rebuilt or decommissioned before converting so they could have greater flexibility of using equipment IMO.

MU's are still used on S. Amboy locals and can run as far west as Matawan, including the Natco siding.

I miss them too on the Coast Line, but push pulls aren't that bad, adn as for the all holy equipment manipulation, there have been times when they were short push pulls for coast line or M and E service, but I would guess that if worse came to worse, and NO push pulls were available for a while, they could run an MU train down the coast line to Matawan, and have the Bay Head Shuttle meet the train up in Matawan and do the transfer there. No big deal, happens every once in a while. So there would still be trians moving, unlike the Midtown Direct servce, where the trains simply wouldn't run if there were no Push pulls.

MUs are still used huh? Well that is good. I remember hearing in here that someone spotted a S. Amboy MU train a few times but every time I have ridden the S. Amboy train it has been push pull. I'll just have to keep watching I guess. Interesting about having LB passengers transfer at Matawan for a Bay Head Shuttle for the rest of the trip. A really smart idea.

99 percent of the time S. Amboy locals are push pulls, but they CAN be MU's......every once in a while one makes its way down there

Between 11kv and 25kv, it's not much difference, though if you want to be really pendantic, the current at the pan is about 1/2 with 25kv, and theoretically it can handle more. More significant would be dumping 25hz, which would shave a bit of weight off of the cars, since 60hz transformers are lighter (this is why aircraft are 400hz - it allows even lighter transformers, and smaller filters for DC supplies). Frequency changes mean little/nothing to AC traction equipment (it's rectified to DC then inverted anyway - as long as the filters can cope with the lower frequency, it's ok), but voltage changes need to be handled somehow. Typically, this is a tap changer on the primary, though there's a few ways to do it. GE stuff tended to have two primaries - they would run in series on 25kv, parallel on 11kv, I think ASEA/ABB uses a tapped primary. In theory, it could be handled on the secondary side as a function of the DC conversion equipment (much like your computer's "international" power supply), though I don't know if this is done in practice. That'd mean no tap changers and their maintenance.

On Silverliners and pre rebuilt Arrows, frequency changes could screw things up because it messed with the firing of the ignitrons - though I'm not sure how GE compensated for this and if it was automagic. It wasn't on the E-60's, I'm not sure about the GE equipped Metroliners (which were Silverliner derrived and 25kv/60hz capable)

Anyway, 11kv/25kv shouldn't "feel" any different, though I wouldn't be too surprised if 60hz / 25 hz did slightly.

Jtgshu wrote:99 percent of the time S. Amboy locals are push pulls, but they CAN be MU's......every once in a while one makes its way down there

Yeah, whenever I'm down in Perth Amboy or as some call it the ghetto (arghhh!) I am always on the lookout for it.

I thought I once heard that some of the NY and/or CT EMUs loose a good deal of power when going from 11kV/25Hz to 12.5kV/60Hz.

Which they never do, right? Switch voltages, I mean.

IIRC the same windings or taps are used for 11 kV/25Hz and 12.5kV/60Hz.

The MN New Haven stuff changes from 600V DC to 12kv 60hz AC. When the system was being cut over, it did switch between 25hz and 60hz. This didn't require a tap change (and, AFAIK, never did on GE equipment). The M-4 and M-6 cars can't run on 25hz power at all, only the M-2, since they were delivered after the changeover.

I don't know if there was power differences between the two, but remember that the old NH power system stunk anyway (it was pretty much always horridly undercapacity). At the bitter end, I've heard that trains would periodically stall because the voltage would get too low (they cut out below a certain voltage).

GE's proposed Arrow I propulsion system could do 60hz operation (optional, as was 25kv, and dynamics, the latter would have resulted in LIRR style single handle controllers), but would be downrated somewhat (40%!) at 11kv. The Arrow IIIs could do 25 or 60hz, I don't know if the rating was different.

From the passenger's seat, IMHO, the NH stuff is a dog on AC, and even worse on DC. They just seem to take forever to get up to speed.

I had a few questions regarding electric current on NJT.

Does anyone know what the voltage is for each line on NJT?

Is the voltage the same in NYP as it is at Sunnyside Yard?

Are all Arrow III's leaving NYP set for the same voltage, (if that is the correct term) or are they set to a specific line?