Many of you out there have those ex-LIRR P72's running around. I know they were designed to run on 650V DC, and standard HEP is 480V AC 3-phase delta. I've been told there's an easy way to convert it, but the explanation I was given didn't seem to make sense electrically. I'd imagine those of you who are traction operators do something similar.

Also, how does one come up with a solid 32V DC source these days without dynamos or axle generators?

If you run 480Volt three-phase power through a conventional 6-pole solid state rectifier, what comes out is between 600 and 650 V DC power depending on the DC load.

fkrock

On the 32vdc, it isn't that hard to come up with 36 vdc marine generators that you can adjust down a little.

Another way is to search out an army surplus 24vdc generator that have an adjustment wheel that allows you to go up to nearly 32vdc.

Four 8 volt golf cart batteries can be used in a coach battery box if your primary concern is simply lighting / fans.

I guess it depends on what you want to do?

David Farlow

As Fred notes, diode rectifiers easily turn 480VAC into 600(ish) VDC. This is the basis of more than one railway museum substation.

To get 32 VDC from 600VDC, the modern solution is a silicon DC-DC converter, ideally one intended for your application, i.e. battery charging. Such devices exist by the thousands on modern light rail and subway cars.

However if your origin power is 480VAC, stick with AC, which can easily be transformed into another voltage. I would suggest shopping for a suitable battery charger designed for either 480, 208, 240 or 120 VAC, and (if necessary) get an appropriately sized transformer. I've seen forklift chargers which could be jumpered to accept 480VAC directly.