HEP Under Catenary

[Acela026]

Today's Photo of the Day featured a GG1 with several Amfleet cars in tow.  

The caption states that "...there weren’t enough head end power–equipped locomotives to haul them, so a number of ex-Army kitchen cars were fitted with engine-generator sets to provide the necessary electricity..." 

This made me wonder: could the necessary electricity not be obtained from the overhead wires? If there was access to electricity within several feet overhead, why was it necessary to have an engine-generator car? Was this an issue of (1) not having a method of transferring electricity between the locomotive? (2) the catenary electricity being out-of-phase or some other electrical issue? (3) causing too much power to be drawn from the catenary? 

Or some other issue I am not considering entirely? 

Thank you in advance!

Acela

[CSSHEGEWISCH]

GG1's and most other passenger electrics were equipped with steam generators to provide heat and air conditioning to the trailing cars.  There was a picture in TRAINS of an NYC T-motor in suburban service with a plume of oil smoke from the steam generator.

Installing HEP equipment would require a fair amount of down time in the shops.

[DS4-4-1000]

The head end power is 480  Volts 60 Hz AC while the Catenary is providing 11,000 Volts 25 Hz AC.  In order to convert one to the other a custom designed motor alternator set would have been necessary. While the voltage is easily changed using a transformer the frequency could only be changed mechanically. (at that time and for the amount of power needed, today a switching power supply could do the job)  When enough HEP locomotives became available the motor generators would become basically scrap because of the unusual voltage/frequency combination.

Instead Amtrak opted for "off the shelf" diesel generators which had a ready market when they were no longer needed and being a standard item would be less expensive to purchase.

[daveklepper]

100% answer!

[rcdrye]

The HEP cars were also used behind diesels as Amtrak's diesel fleet at the time was made up of steam generator equipped E-Units and SDP40Fs.  Corridor trains heading for Boston got HEP cars.  The first Amtrak diesel equipped with HEP was the GE P30CH in 1973.  The HEP-equipped F40PHs that began arriving in late 1974 often found themselves leading trains carrying steam generator cars until the conversion was complete in 1979.

The ex-Army cars are an interesting subject themselves.  Built for the Korean War and never used, they were conveyed to Amtrak for $3000 apiece in 1973.  The short kitchen cars ended up as HEP cars and baggage cars, the full length hospital cars as Baggage-dorms and Lounge cars.  The ones that lasted beyond the 1970s ended up in work train service.

[rcdrye]

The two european test locomotives, from France and Sweden, also used the HEP cars as their HEP equipment was not U.S. compatible.  The Swedish Rc4 was, of course, the basis for the very successful AEM7.

[rrlineman]

actually the 1st 15 E60's were steam generator equipped, and the last 10 had MA sets installed. all were skid mounted in the carbodies. As the steam heated cars dwindled, the Steam generators were replaced with spare MA sets that Amtrak had bought, then the fuel tanks were removed and replaced with steel plates as ballast.. learn this when I was a junior lineman back in the 70's. had to be careful walking on the roof when dealing with broken Pans. with the exception of the 2 sold to Navaho mining, all the E60's had MA sets up to their scrapping. even the ones sold to NJ transit kept theirs. unknown if the 600 at Strasburg (1st E60)has it since a lot of it's electrical gear was removed before donation. Mike 36-1/2 yrs with Amtrak