Abstract: A hydrocarbon production installation comprising a surface station and an underwater hydrocarbon extraction facility, the surface station and extraction facility being electrically linked via an umbilical cable, the installation further comprising means for transmitting first and second components of a communications signal and power from the surface station to the extraction facility via the umbilical cable. The transmitting means including means for passing the communications components through the umbilical cable in a balanced manner. The transmitting means further comprises means for transmitting the power through the umbilical cable superimposed on the communications components, and the facility comprises means for receiving the communications components and separating the power from the communications components.