Abstract: An apparatus controls the operation of a hydrocarbon production well. The apparatus includes a supply means for providing an electric power supply. The apparatus also includes a plurality of electrically operated actuating devices. The actuating devices can be a plurality of electric motors. The apparatus includes drivers responsive to the power supply for providing a drive signal for the actuating devices. The apparatus also includes a control assembly for applying the drive signal to the actuating devices in a multiplexed manner. The power from each driver creates a power input signal. When there are more than one input signals, they are multiplexed so that a single signal is received by the actuating devices.

Abstract: Apparatus for use in controlling the operation of a hydrocarbon production well comprises: supply means (1) for providing an electric power supply; a plurality of electrically operated actuating devices (M1 - - - M10); drive means (8) responsive to the power supply for providing a drive signal for the devices; and control means (3, 5, 8, 12, 14,16 - - - 32) for applying the drive signal to the actuating devices in a multiplexed manner.

Abstract: An underwater hydrocarbon production system comprises power supply means (1,3,4) at or for use at a remotely located station (2) for providing DC; electrical means (6) at or for location underwater for using DC to provide power for an underwater device; and transmission cabling (5) for transmitting DC from the power supply means to the electrical means.

Abstract: A hydrocarbon production system comprises a topside installation connected to a underwater distribution unit 4 by an umbilical 3. The unit 4 is connected to Christmas Trees 8, 9 and 10 by respective ones of jumper interconnects 11, 12 and 13. Each Christmas Tree may comprise one or more of an electrical actuator 14, flow rate control choke 16, pressure and/or temperature transducers 18, down hole measurement transducers 18a and/or a down hole safety valve 21. Electrical power is transmitted to the unit 4 by a high voltage transmission cable forming part of the umbilical 3. A transformer forming part of the unit 4 steps down the voltage transmitted over the umbilical 3 to a level suitable for use by the electrical devices 14, 16 and 21. Power and control of the devices 14, 16, 18, 18a, 21 is effected by an underwater controller 5, 6, 7 associated with its respective Christmas Tree 8, 9, 10.