• Why is 25 KV used for Hoboken and Coast Line?

  • Discussion related to New Jersey Transit rail and light rail operations.
Discussion related to New Jersey Transit rail and light rail operations.

Moderators: lensovet, Kaback9, nick11a

  by Passaic River Rat
I think the Hoboken Division was changed to 25kV back when Conrail owned and ran everything. They replaced a DC system back before the Kearny Connection was a serious consideration.

The NJCL was 11kV until a few years ago. I think when some of the 11kV stuff had met its useful end they decided to start standardizing.
  by DutchRailnut
25kv is easier to obtain and requires a lot less to be supplied by utilities.

The conversion of the Hoboken Division from 3000 volts DC to 25000 volts AC was completed in August 1984.

NJT Rail Operations took title from Conrail on January 1, 1983 - the re-electrification began under Conrail and
was to modernize the M&E electrified routes using at first A3 MU cars for all trains...

I rode trains on the final day of operation of the old DL&W/EL MU cars and I recall that fans gave them quite
a sendoff - there was a large contingent riding the trains and out along the ROW then...

The drawback of the A2(retired) and A3 MU cars are that they can not change voltage sources "on the fly"
the way modern electric locomotives can - internal switches need to be used for this change - and these
MU cars needed to be marked and noted which power source that they were assigned to - these cars do
have "11KV" or "25KV" triangle shaped stickers on the front ends to show which power source they use...

  by Ken W2KB
Some 20 years or so ago I was at a meeting with NJT high level power engineering management concerning availability of transmission service for possible electrification of the RVL and Lehigh Line to West Trenton. I asked the off-topic question out of curiosity, and was told that 25kV was selected for the M&E as at the time Amtrak planned to upgrade the corridor to 25kV 60Hz. Congress eventually declined to fund the Amtrak project, but by that time the M&E project was too far advanced to consider changing back to 12kV. It would have required redoing engineering designs, equipment orders, etc. as well as substantial delays to completion risking breakdown of the old DC system and equipment.

There are several advantages to 25kV versus lower voltages. One is that for a given amount of power flow through the conductors, doubling the voltage results in half the current. Power losses in conductors are a function of the square of current times the resistance/reactance of the conductor, so lower current results in substantially lower power loss. The lower losses at higher voltage also allow for fewer feeder substations since they can be more widely separated and thus a considerable cost savings.

The largest substation owned by NJT is the Meadows sub (adjacent to the MMC) and is fed from PSE&G 230kV transmission in a flow through bus design. The other sources of traction power to my knowledge are all fed by JCP&L and I do not know what voltage level feeds them. JCP&L does not have a lot of transmission level facilities; a lot of its system is 34kV subtransmission.
Last edited by Ken W2KB on Sun Nov 08, 2015 4:03 pm, edited 1 time in total.
  by R36 Combine Coach
25k is also in use north of New Haven. In theory Arrows can make it as far north as NHV from WAS.
  by Fan Railer
jackintosh11 wrote:North of NYP the electrification is 12.5 KV 60 Hz. Does that make a difference?
60 hz vs 25 hz is a completely different story altogether; and yes, it does make a difference.
  by DutchRailnut
a car designed for 25 hz can run on 60 hz, only real difference is transformer core of 25 hz has lot more iron and is therefor a lot heavier.
In old days rectifiers made difference, but with solid state rectifiers the car still gets same DC for power circuits and Motor Alternator.
  by Jeff Smith
Admin Note: I clarified the title a bit.

Let's be clear; I think this got confused a couple posts ago. The topic originally concerned Voltage (kv) vs. Hertz (hz). Hertz is frequency.

If Ken could clear up the details, I'd be appreciative. I'm not an engineer (of train or any other kind), so don't ask me.

I do believe clearance on the New Haven line (specifically near Mt. Vernon) had something to do with the selection of 12.5 kv, but don't hold me to that, and also, that's Metro North, NOT New Jersey Transit, but as a point of reference, it's interesting. The switch to 60 Hertz I think had to do with commercial availability and the disrepair of the NH Cos Cob power facility. 60hz is the North American standard (vs. 50 I think in Europe).
  by DutchRailnut
Amtrak's original plan was to re-electrify entire NEC with 12.5 KV 60 hz, and asked MN to do same.
MN complied but then Amtrak decided to go with higher voltages were possible. the area from New Haven to about Portal in joisey will never see higher than 12.5kv due to clearances.
  by Backshophoss
From Shell to CP Gate was part of the old NH power grid,that MN converted to 12.5 kv 60 hz from 11kv 25hz.
Amtrak owns/controls the entire remaining PRR power grid at 12,5kv 25 hz from WAS to CP Gate.
The NJT extension to Long Branch at first used "excess" capy from the PRR grid,after CR shut down the use of
electric freight motors and the catenary needing power off the PRR grid,was converted to 25 kv 60 hz due
to maintaince problems with the older 25 hz equipment
The old DL+W DC grid was worn out and replaced with the current 25 kv 60hz grid.
Amtrak built new the 25 kz 60 hz power grid east of New Haven to Boston.
  by F-line to Dudley via Park
Do they have any plans (or long-term desire?) to convert the last 25 Hz portion of the NJCL to 60 Hz/25 kV when they've got their frequency-agile next-gen EMU's ordered. A little bit weird to have their own phase break to maintain on a branchline.