I want to know the answer to the following question:
How did non-standard gauge trains start to operate with high-voltage AC?
All the background I'm provided with is that "The MGB constituents Furka-Oberalp-Bahn (FO) and Brig-Visp-Zermatt Bahn (BVZ) introduced their electric services in 1941 and 1929 respectively, adopting the already proven RhB system.". Is that enough to answer the question?