Discussion relating to the operations of MTA MetroNorth Railroad including west of Hudson operations and discussion of CtDOT sponsored rail operations such as Shore Line East and the Springfield to New Haven Hartford Line

Moderators: GirlOnTheTrain, nomis, FL9AC, Jeff Smith

  by RailBus63
http://www.ctnow.com/news/local/scn-sa- ... ines-local

According to this article in the Hartford Courant, CT governor John Rowland has approved a plan to replace the entire current fleet of electric MU's on the New Haven Line as well as build a new maintenance facility in New Haven. The plan is still unfunded.

There were a few interesting tidbits in the article:
The current 342-car New Haven Line fleet is more than 30 years old, 10 years past its intended life span.
As usual, nobody checks facts - the M-4 and especially M-6 cars are a lot younger than 30 years of age.

Transportation officials initially estimated that replacing the fleet would cost $2 billion because the New Haven Line works on a dual propulsion system, requiring it to purchase as-yet-undesigned M-8 electric rail cars.

But the DOT reduced the cost by proposing to buy only one M-8 for every three cars -- the other two will be the much cheaper M-7s, which run only in New York.

"We realized that the M-8s are over-powered," said Harry Harris, head of the Bureau of Public Transportation, part of Connecticut DOT.

According to the plan, the M-8 cars are strong enough to propel two M-7 cars while the train goes through Connecticut, which is powered by ground-level and overhead electricity. Once the train passes into New York, where trains run solely on ground-level power, the two M-7s can propel the M-8.

"Metro-North is fairly confident that it will work," Harris said.
Interesting, to say the least.


  by Nasadowsk
As always - try the obvious. asdfg works as a user/pass. or was it asdfgh. I forget.

Don't you love free login news sites? :)

As for the design? I bet everyone's getting their facts mixed up. The M-8 cars are likely just transformer cars to feed the M-7s, which is the blindingly easy and obvious answer anyway, since there's zero need to have sepperate propulsion systems anyway (AC inverters just care the DC link is fed, not what is feeding it).

I'm guessing what the CDOT guy really means is that traction power will be supplied by the M-8 cars on catenary, and the M-7 cars on third rail. It's easy to see how statements about this can get tangled up between engineering and the spokesperson...

  by JayMan
Why can't the current bypass the inverters if the cars are being fed AC via the pantograph? All you would seem to need is the middle car serve as the receiver/transformer which would then feed the A/B cars the AC current when running on catenary. Of course, the reverse would operate when the train is running on 3rd rail -- the A/B cars would feed the middle car current from the AC inverters.

Necessarily 3-car sets would be interesting -- no more 5-car consist like on some of the Stamford locals. Of course, the consist would be kinda strange looking since the pantograph equipment would be on the middle car only, unlike all cars in the M-2/4/6's (well, actually I mean the box gear -- exactly what are those on the M-2/4/6s anyway?).

  by dgianna
I think that the M-8s will be sandwiched between a pair of M7s.
This would suggest that the M-8 will be a cabless, motorless trailer equipped with pans and 3rd rail shoes. The dc current would be bussed to the pair of M-7s (which would probably NEVER lose electrical contact!), and the M-8 would provide power to the pair of M7 cars when in ac territory. The M-8 would have the transformer(s), rectifiers to provide dc for the M7 controllers/inverters.

Two things aren't clear from this proposal, however. First, if the M7/M8 sets are purchased, will they also replace the M4/M6 fleet? It sounds logical even though they will be less than 30 years old in 2009 (M4s date to 1984, the M6 to 1988), as they would be a small, non-standard fleet (81 cars). Secondly, would the M2 rebuild program continue? It seems that the cars would be rebuilt just in time for retirement. Hardly seems to make sense.

  by Nasadowsk
The inverters are what control the motors. Catenary is 60hz all the time (hopefully!). Apply 60hz, 480V power to an M-7 traction motor while it's off, it burns out from the very very very heavy inrush currents. Or, if it doesn't, it breaks the gearbox attached because it tries to spin up from zero to full speed in abourt 1/60ths of a second.

The inverter varies the voltage and frequency being fed to the motors (and phase - they're 3 phase and thus reversed via software - there's no reverser switch on them). This way, the motor can be run in a controlled manner - any power level/speed you want, from zero to maximum (as defined by software, at least).

Under the M-2/4/6 cars is a LOT of interesting stuff...

Oh yes, you'd have a bit of gear under the center cars too, because that's where the transformer and rectifier (actually, I'm guessing it'll be a converter, i.e. a constant voltage supply) will be. Somewhere, they'll have to be a tap changer (roof, like an AEM-7, or in the transformer tank like GE MUs have), and a few other things - there needs to be a way of isolating all the third rail shoes from the main bus while in AC mode a) for FRA regulations and b) so the train doesn't inadvertently feed the third rail while changing over.
  by N340SG

That seems to be the most sensible way to do it. If you use 650VDC as the baseline operating voltage, then the M-7 cars continue to operate normally. The propulsion, dynamic brake, and APS work as designed. You would only need extensive software changes, and possibly, though not necessarily, beef up the buss line cables to handle the amperage of a triplet instead of married pair. (Certain trainlines/couplers also get rewired for triplet as opposed to married pair operation, so the doors don't open on the wrong side in half of a six car train, for example.)

The M-8, you design with contact shoes and buss line. Then, you simply transform and rectify the catenary input to 650DC. (Full - wave rectifiers/stabistors prevent backfeeds.) Then, feed it into the DC buss line.
Then you hang APS and propulsion inverter boxes on your M-8. Depending on the weight of the M-8, you might even be able to use the existing M-7 propulsion inverter boxes.
Now, you have your entire triplet with propulsion and dynamic brake, at all times. No dead cars to haul. FRA loves that. Each car also has it's own APS. If one craps out, you still have the other two cars of the triplet with functioning APS. You incorporate the existing M-7 APS load distribution so you would have some Air Conditioning even in a car with nonfunctioning APS.

Since regenerative braking is not used, diode packs keep the third rail from being backfed in any way.

Last edited by N340SG on Mon Jun 14, 2004 10:19 am, edited 1 time in total.

  by Nasadowsk
For a transformer of that capacity, I'd figure about 10 tons, or more. The easy answer to weight distribution is to make the M-8 part of the train a two car set - one car is the transformer/rectifier, the other can have 4 inverters, for powering both cars, and both cars would have motors on them, then. If done right, you'd have a train that effectiely weighs no more than an M-7 of the same # of cars, and performs the same on third rail, and much better on catenary.

  by JayMan
It seems like the intention is to have one car with caternary equipment as the middle of the triplet and M-7 cars with 3rd rail taps as the end cars. I can see why having all the transformer equipment solely on the middle car of a triplet might make the car too heavy -- but it looks like the idea is to design a car that can be sandwiched between two M-7's with minimal changes for cost effectiveness. Having two middle cars (to distrubute the weight) would seem to defeat this purpose.

But that seems to be an effective concept: Have the end cars of the triplet supply power to the whole set while in 3rd rail territory and the middle car to the whole set while in catenary terr. All cars have propulsion and dynamic brake and if one fails two in the triplet still have power.

  by DutchRailnut
The middle car has no own propulsion system Jay its an unpowered trailer.
and since it won't have traction motors that car has no dynamic brake either.

  by JayMan
Well that doesn't sound like a good idea. I suppose giving the middle car propulsion (and hence dynamic brake) will make the car too heavy?
  by N340SG
The middle car has no own propulsion system Jay its an unpowered trailer.
and since it won't have traction motors that car has no dynamic brake either.
Can you expound on that a little, if you have that info?
It seems totally inane to have the M-8 be a dead car by design, unless some logistical problem necessitates it.
I'm not so sure that the off- the- shelf M-7 is designed to push a train with 33% dead cars.


  by DutchRailnut
they had 4 proposals from Bombardier.
all with differed drawbacks.

A} was married pair but only 50% propulsion and two powered axles per car to save on weight for AC equipment. one car would only have one HVAC unit due to pantograph. only 50% power per car

B} was one powered M7 car and a unpowered control car to carry extra equipment. again only average of 50% power for both cars

C} was A-T-B proposal with two M7 style end cars and unpowered trailer to carry the high voltage gear, T will only have one HVAC unit as other side is occupied with panthograph both cars at full 100% power for average of 75% for three cars compared to M7's

D} married pair with all equipment like M7 but with transformer etc sueezed in, making both car prohibitivly heavy 100% power for each car but only one HVAC to save on weight.

Again these are only proposals and Conndot preferes choice C. but the funding is not secured yet, and The techinical details need to be finalised,
and the contract needs to be put out for bid, and the bids have to be compared and investigated for political snakes inther grass.

then the cars can possibly be built.

  by Nasadowsk
Like I said earlier, if they could go for two intermediate cars, they could make one the pan/transformer/convert/changeover car, but equip it wih traction motors on both trucks, and have another car with 4 inverters, two for it, two for the transformer car. NJT's MUs are sort of like this - they feed one truck on the one car, both trucks on the other, but only one car has the inverters on it.

Option D is impossible, A and B would only give 50% powered axles. Thus, C, which gave 75%, wins.

Of course, there's a theroretical chance that MN and CDOT could convince the FRA that the center car isn't a locomotive, thus wouldn't have to meet FRA cab end standards (no cab anyway), thus the frame could theoretically be lightened, but this would be offset by the fact that you'd have to strengthen it for the transformers, anyway.

I'll go out on a limb here and estimate the weights to be 127,000 lbs for the end cars, 120,000 for the middle cars. The heavier ends reflects the added equipment they may need + gearbox mods, the lighter middle reflects the missing cab, motors, gearboxen, and stuff. I'm guessing an M-7 body on dead trucks is about 90,000-100,000, thus about 20,000 for the transformer, 2,000 for the pan, 2,000 for changeover/converter/misc. If they decide to not build in 25hz capability (which is really useless anyway), drop the tranny by a few thousand. An A-TT-TI-B type system would be about the same, with the second (4 inverter) car being about the same. maybe with it having the pan to compensate for TM weight on the TT car.

Like I said, it would be concieveable to add 2 cars between the m-7s, have 100% powered axles, and no real weight penalty. This is done elsewhere and it works just fine. As a bonus, you can drawbar the cars and all and get rid of 3 couplers per 4 cars on every train, which would boost reliability.

But having 75% powered axles isn't a problem, look at what a locomotive hauled train has...

  by DutchRailnut
It would not be conceivable for shop purpose as Stamford only has capacity for 3 cars on each track.
and New Haven MI would already need to be done at old Amtrak shop/cdot shop.
Again we can talk about what if , or how should, or they should, but it won't get anywere unless you aply for job in one of engineering departments.

  by JayMan
Nasadowsk wrote: Like I said, it would be concieveable to add 2 cars between the m-7s, have 100% powered axles, and no real weight penalty. This is done elsewhere and it works just fine. As a bonus, you can drawbar the cars and all and get rid of 3 couplers per 4 cars on every train, which would boost reliability.
Only problem is you've obligatorily got 4-car multiples per train. Next consist after 4 is 8 -- no 6 car trainsets.