>>232808Jean Jacques Heilmann, took out his patent for a steam-electric locomotive on July 18, 1890, and the first prototype was built in 1892-93. Heilmann and his coworker Drouin began with static tests to determine whether DC or the recently introduced 3-phase AC would be most suitable for their purposes. It was quickly found that DC would be best, as it allowed the steam-engine and generator to work at a constant efficient speed, while the traction motor speed could be quite different. The Heilmanns were in many ways a success, but not many were built. It was complex and expensive, and heavy for the power it generated. One serious disadvantage was that it needed a crew of three; a driver, a fireman, and a "pilote électricien" to manage the electrical system It was one weird but innovative locomotive.