After the D&H merger the Parsons Vale realized that the scope of planned future electrification would involve paying large fortunes to the third-party engineering firms that were big enough to manage these project, and decided that it would be better to have an inhouse design & engineering division to do that work.
The division électrification ferroviaire (railway electrification division, or RED, in english) was then formed with staff drawn from the PV&T & TdM’s electrification maintenance departments, and was immediately tasked with electrifying the D&H’s northern line from Albany to Montréal. This was a fairly slow and expensive first project (but not nearly as expensive as the management fees the Parsons Corporation or Morrison-Knudsen wanted), but by 1988 the wires were up and new class I & J motors were handling all of the mainline trains from Albany north.
Pleased with these results, the DEF was then tasked to start electrifying the southern half of the D&H (Albany-Binghamton-NE Corridor.) The plan for this project was to (eventually; it took until Conrail was cut apart for parts to get rights to electrify from Sunbury to Harrisburg) extend the D&H’s inherited sections of the PRR’s once-huge electrification (the Columbia & Port Deposit, Atglen & Susquehanna, and Philadelphia & Thorndale) , so the choice was made to convert to 25KVAC instead of the PV&T’s 3000VDC standard.
This electrification was faster, finishing a longer section (and some of the tangle of trackage in the Wyoming Valley) for a somewhat lower cost per mile than the O.G. DC electrifications, so the Parsons Vale decided that this is what it would do for further electrifications outside of Québec & upper New England.
In 1993, the DEF moved its offices to Binghamton, NY, so it would be more central for future (AC) electrifications, and it was off to the races; not a single Parsons Vale electrification project since then has been contracted anywhere else, and the division has since electrified around 3500 miles of railroad (if you discount the initial cost of electrification, it’s significantly cheaper to operate under wire instead of with diesels, and the Parsons Vale Trust operates under the happy condition of not needing to chase the next quarter’s numbers.)
Some external work has been done as well; the REM’s light rail project in Montréal had the DEF as their electrification contractor, as did Ottawa when they built the Confederation Line. (North America is, sadly, not a hotbed for electrification once you get out of the Parsons Vale Trust’s orbit, and the rest of the world is a much more competitive market than North America.)