I came across an interesting paper that deals with the electrical system conversion topic, and touches on the NEC.
http://www.ltrc.lsu.edu/TRB_82/TRB2003-001318.pdf
It seems that while conversion from 25 Hz to 60 Hz would eliminate the inefficiency of the converters, increasing the frequency also increases the reactance with a corresponding voltage drop across the line. Simplification has its costs.
The above paper is dated Nov 2002. I have no argument with its conclusions as of 2002. However several technological changes have come about in the past 10 years. MNRR building of the M-8s to operate dual mode at a reduction in weights vs the older Ms. Inverters, rectifiers, and transformers constructed todday weigh much less than 10 years ago. Remember AC traction freight locomotives were not even offered 10 years ago.
The reactance problem has been reduced the past few years. Most motors today are capacitance wound to give a zero power factor.
It appears that a gradual conversion of the NEC would be the best. Power required to run all the traffic by 2030 leads to a major power demand increase. A gradual conversion is indicated with the 25 Hz equipment retired from service at one location moved to another still using 25 Hz.
The order to convert needs very much thought. The 2012 vision report gives some guidance. Since AMTRAK wants to have 4 roun trip ACELA trips an hour between NYP - PHL ( on to WASH ). + regional trips and NJ Transit trips during rush hour. That would seem to indicate the NYP - PHL segment will need more addditional power than other segments. why spend all that money on 25 Hz equipment when 60 Hz may actually cost less ? Brings up many questions ?
I probably should have specified inductive reactance, causing resistance to current flow in the cat wire .
I see reference to motors. The motors are the same for all three types of operaton, 25Hz or 60Hz, 12,000-12,500V or 25,000V (the latter only with 60Hz.) The differences are in the transformer arrangement and the electroncs and the control. The older equipment did use dc motors (beginning with the washboards and the jets and first silverliners, before that it was ac commutator motors than indeed could run either on dc or 25Hz ac but not 60Hz), today M8 and all new equipment use ac Hystoresis non-synchronous (slip) slanted bar ac motors, but there is a dc “rail”. In otherwords, the ac traction power is first converted to dc, and then converted back to ac at the appropriate frequency for the motor rotational speed. As far as I know, the M8’s cannot operate on 25Hz, because it was decided that the transformers necessary for that operation were too big and too heavy. All NJT mu cars after the very first can operate on 25Hz or 60Hz, but the transformer tap changes that are necessary apparently require manual switches to be thrown, one on the roof and one under the car! So some NJT mu’s are setup for 60Hz operation and run exclusively out of Hoboken, with midtown direct handled by loco-pulled-pushed consists. Others are setup for 25Hz operaton and run Pernn Station (sunnyside) - Trenton. All Amtrrak and NJT electric locomotives can handle all three ac power systems and switch at speed.
I don’t know the power system on the Long Branch electrification. If it is 60Hz, that would be that loco-push-pulls are normal there and not mu’s.
None of Amtrak’s or NJT’s electric power can run on 600V DC third rail. The LIRR, MetroNorth and Amtrak diesel-electric-electrics run diesel or 600C DC third rail, but no ac (except the motors themselves). The new NJT diesel-electric-electrics do not have third rail capability and are
Dave K; good explanation— the only thing some readers may not understand is that the lower the frequency the more iron that is needed in a transformer thence the reason they are heavier. That is the reason 25 Hz transformers can accept 60 Hz but a transformer built exclusively for 60 Hz cannot accept 25 Hz. trivia – if power systems had to start over today they would prefer 100 Hz for even better transformer use. This is one reason that modern transport aircraft use 400 Hz. Also the motors are much smaller at 400 Hz as they can run at higher speeds than the 1800 / 3600 rpm limit of 60 Hz motors…
The North Jersey Coast Line starts out with the NEC electrical system, but changes to 25 Kv 60 Hz at Matawan, according to a detailed wiki article:
media criticism of cost
Along with what seem to be some constructive ideas?
So mu’s cannot run to Long Branch, only loco hauled and pushed trains. Good explanaition abouit the transformers. For a given amount of power handling, assuming divided coils can be series or parallel, the weight and amount of iron for a 30Hz transformer would be double that of a 60Hz transformer, so 25Hz would be more than double! There have been advances in special alloys to reduce transformer wieght in general, and these find use in power supplies for comunications and navigration equipment on military aircraft, but these steel alloys are very very expensive.
At one time I designed transformers for Mystic Transformer Co. in Winchester, MA, commuting from my MIT dorm room via bike and B&M. The text book I used was written by Ruben Lee. I’d have to get a new copy and reeducate myself if I were to begin such work now.
The 2pm open platform wood gate Lowell train from North Station had my Raleigh bike on either the front platform behind the road-switcher or the rear platform as a regular fixture three times a week.
The media seems to have one of two reactions to rail passenger plans:
If you tweak the system for incremental increases in speed, they say it’s not true High Speed Rail;
And if you announce a plan for true HSR, they say it’s too expensive and you could tweak it for less.