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| Re: NJT Board considering large capital expenditure on new rolling stock, including DMs & EMUs, July (645539) | |||
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Re: NJT Board considering large capital expenditure on new rolling stock, including DMs & EMUs, July |
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Posted by WillD on Mon Jul 7 15:30:22 2008, in response to Re: NJT Board considering large capital expenditure on new rolling stock, including DMs & EMUs, July, posted by trainsarefun on Mon Jul 7 13:30:20 2008. "Too heavy" really had more to do with the fact that NYP access is an iffy proposition at best and thus would not justify the weight they'd be saddled with in the interim period. The M8s already weigh something like 141,000 lbs, so a few thousand pounds added to the transformer core isn't going to make them unworkable. However, from what I gather ConnDOT and the MTA were not enamored with the idea of shelling out for the additional power and maitenance that weight would generate when they may never operate on 25hz wire. An LIRR multisystem EMU would be an entirely different beast from this perspective because it'd be able to make profitable use of 25hz wire on a regular basis. So designing for that frequency and accepting the weight penalty of the low frequency transformer would make more sense.The Karlsruhe tram-trains, the GT8-100C/D, as well as the tram trains in Kassel and Saarbrucken, all use a medium frequency transformer to reduce weight. They only take power from overhead wires, be they AC or DC, with no provisions for third rail operation. This actually slightly increases the complexity relative to a thid rail unit because all power comes through the pantograph. The medium frequency tranformer reduces the core weight by inserting a device that bumps the input frequency up before it enters the transformer. This allows for a tranformer small enough and light enough to be placed on the roof of the railcar. Unfortunately it is also somewhat restrictive in terms of power output, with current units toppong out at around 1.5 MW, short of the M8's power requirements and a very long way from the needs of the NJT dual mode locomotive. |
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