Had to deal with that yesterday in a french train:

A protected source of electricity... that prevented me to use an electrically-powered of some sort that I often employ in train for my work.

Is it because they do not want to provide electricity for commuters/travellers? In this case no, because there are power plugs elsewhere in the train. Simply, as I've been told there by the controller, this plug is covered because it's a 380V and they don't want kids/people to toy around with so much electricity (so why is it written 230V????).