I searched much time, too, but here is the match! http://pagesperso-orange.fr/titanic/index.htm
click to enlarge the dynamos plan /in the site is "implantation de la salle des machines electrices". In the upper right corner on the plan. The text is: "Switch board gallery" and "switch dynamo pillar". Here can you look a rounded L form drawing. That the switching gear.
