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| Re: The LIRR President Speaks (244471) | |||
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Re: The LIRR President Speaks |
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Posted by nasadowsk on Sat Apr 22 21:20:38 2006, in response to Re: The LIRR President Speaks, posted by Dutchrailnut on Sat Apr 22 19:08:23 2006. If you think for a moment that a M-7 with 1000 hp per car and AC propulsion uses more electricity than a M-3 with DC propulsion and everything wasted through Grid resistors at 660 hp per car your sadly mistaken.Dutch, you're wrong here. You're violating the laws of physics, pure and simple. The resistors are in SERIES with the traction motors, thus the maximum current through them = the max current through the TMs, which has to be limited on acceleration (the LIRR limits the M-1s to around 300amps). Since the voltage at the third rail = 750 volts (for all intents and purposes), the only thing that's changing during acceleration is the resistors are burning less and less power, and the motors are burning more and more, but the TM current never gets much above the limit setpoint. The DC drive's less efficient, but ONLY durring the times the acceleration resistors are in the circuit, which if I recall correctly, is alarmed at 20 seconds or so on the LIRR's cars (per Budd's book). An AC inverter drive's more efficient because of this lack of series resistance, and little else. And they're nowhere near 100% either (80 - 90% is what you'll realistically see). Chopper DC drives (i.e. phase angle as seen on the Silverliners, pre rebuild Arrows), is as efficient as AC - the only reason NJT saw a 7-10% power drop on the Arrow III rebuilds (per conversations with the engineer involved on the project) was regen durring coasting/braking means a reduced HEP load (as seen by the catenary, the actual load is still the same). It's a known fact the M-7s use a LOT of power - they were derated once on the LIRR already because of this (the infamous 850amp per car limit). They as currently are operated, simply cannot use all 1000 HP, or even close (a more reasonable limit is 750V * 850 amps = 854 HP, but we need to knock out HEP, assuming 30Kw, that's 814HP, then assuming inversion losses, somewhere between 700 and 800 HP, with 750 being the logical number) The Weight is something nothing can be done about the car structure which must be capable og a 1000 000 crush load is never gone weigh less than what they are. 1 million lbs? Hint - read the FRA's regulations - it's 800,000 lbs as of october 2005.: (a)(1) Except as further specified in this paragraph or in paragraph (d), on or after November 8, 1999 all passenger equipment shall resist a minimum static end load of 800,000 pounds applied on the line of draft without permanent deformation of the body structure. (2) For a passenger car or a locomotive, the static end strength of unoccupied volumes may be less than 800,000 pounds if: (i) Energy absorbing structures are used as part of a crash energy management design of the passenger car or locomotive, and (ii) The passenger car or locomotive resists a minimum static end load of 800,000 pounds applied on the line of draft at the ends of its occupied volume without permanent deformation of the body structure. (3) For a locomotive placed in service prior to November 8, 1999, as an alternative to resisting a minimum static end load of 800,000 pounds applied on the line of draft without permanent deformation of the body structure, the locomotive shall resist a horizontal load of 1,000,000 pounds applied along the longitudinal center line of the locomotive at a point on the buffer beam construction 12 inches above the center line of draft without permanent deformation of the body structure. The application of this load shall not be distributed over an area greater than 6 inches by 24 inches. The alternative specified in this paragraph is not applicable to a cab car or an MU locomotive. (4) The requirements of this paragraph do not apply to: (i) A private car; or (ii) Unoccupied passenger equipment operating at the rear of a passenger train. Further, the carbody weight is hardly the dominating factor in railcar weight. In most equipment, the propulsion system weighs far more. It's true for the Silverliners, the M1/2/3/4/6, the Arrows, NYC subway cars, etc etc etc. I'd be surprised if the M-7's carbody - the raw carbody itself - is much over 25,000 lbs, and I doubt it's significantly heavier than the M-1/3 body - probbably 5,000 lbs max. The M-7's are twice as fast accelerating than the M-3's who could never operate at full rate. Nope. And the M-3's pathetic rate's simply because the LIRR yanked the P23/P4 rates on the the older cars years ago to keep from getting hit with demand charges by Lilco. They are fully capeable of accelerating as fast (in fact, faster) than the M-7s - it's simply that they're not set up to. From what I've been told, P2 is about 370 amps on the m-1s at least. Likely a tad higher on the m-3s. DB is a LOT higher on the m-1s, by nearly a factor of 2. Assuming 370 amps, that's about 370hp per car acceleration rate on the '1s, thus 8 hp per ton on the '1s, and assuming 750hp on the '7s (it's damm obvious they run nowhere near 1000 HP), Gee, 12hp per ton. That's not twice as fast, that's maybe 50% faster out the gate. And they fall on their faces at higher speeds, just like the old stuff does. P2 works out to about 1.2mph/s per Budd's book. The M-7's spec'd acceleration was 2.0 mph/s assuming 1000 hp. I'm going to pull a number out of my ass and say it's about 1.5 or so. It's certainly NOT 2.0 - that's where the Silverliner and Arrows are, and the M-7s are NOWHERE near as fast. Further - if the M-7s really WERE twice as fast, then the LIRR would be chopping a LOT of time off their schedules. They're not. In fact, schedules have barely changed at all. Really, you should run some sort of sanity check on your statements in the future, Dutch. You're a great guy on operations / rulebook, but engineering, you're constantly making a fool of yourself with... |
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