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HEP requirements
https://www.rypn.org/forums/viewtopic.php?f=1&t=25521		 Page 1 of 1
Author:  EDM [ Tue Jul 01, 2008 4:21 pm ]
Post subject:  HEP requirements
Can someone give me an idea of HEP requirements for a typical air-conditioned commuter coach? Many years ago, I saw an LIRR genset in Morris Park; it had a 3-71 and I recall the nameplate saying something in the neighborhhood of 18 kW.

I have been using this as a guideline, but wonder if it is accurate any more. IIRC, some of the Amtrak units have 800 kW HEP alternators. At 20 kW per car, this equates to a 40 car train, not too likely to be seen on Amtrak! (Yes, I know about the AutoTrain, but the car carriers don't use that much juice for lights.) Or is the extra capacity for diners, hot water for showers in sleepers, etc.?
Author:  SZuiderveen [ Tue Jul 01, 2008 6:02 pm ]
Post subject:  Re: HEP requirements
A typical modern commuter coach (single level) will have a 10-12 ton air conditioner, but it will typically also have a "re-heat" circuit, to help with dehumidification. Once the car has stabilized, you can typically get by with 25-30 Kw of power, but if you are in reheat season, you will need 50 Kw.

The old LIRR car with the Delco plant you are referring to only has 6 ton of air conditioing and no dehumidification.

Modern double decker cars have a pair of 10-12 ton air conditioners; MARC Train Service in Washington-Baltimore has found out that its old 425 Kw HEP plants run into trouble bringing up a seven car train from dead cold/hot (depending upon season) without phasing in the cars. The new Wabtec/Boise locomotives presently on order to replace all of their diesels will have 800 Kw HEP plants to meet the demand.

I am familiar with a former Amtrak Capitoliner converted into a geometry car, but with its original HVAC. It cannot run 100 % of its heat (floor and overhead) on its 55 Kw diesel generator without overloading it.

Steve Zuiderveen
Author:  EDM [ Tue Jul 01, 2008 9:37 pm ]
Post subject:  Re: HEP requirements
Steve,

Thanks for all the information. I thought my 20kW number might have been a bit low.

My day job is in a plant where we have to control humidity, so our steel stock doesn't rust, and we have similar "re-heat" equipment. Sometimes we have dehum, hot gas and heat on all at the same time to control humidity, and our energy bills are huge for a plant our size.

I never got to ride in those LIRR cars during the summer, but 6 tons doesn't sound like a lot of AC capacity. I do remember they had a lot of complaints, though, back in those days-
Author:  JimBoylan [ Wed Jul 02, 2008 10:03 am ]
Post subject:  Re: HEP requirements
SZuiderveen wrote:
I am familiar with a former Amtrak Capitoliner converted into a geometry car, but with its original HVAC. It cannot run 100 % of its heat (floor and overhead) on its 55 Kw diesel generator without overloading it.
If that's one of the 11 extra cars for Harrisburg service added to the Metroliner oder, it was intended to be supplied from overhead wire with comparatively unlimited capacity.
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