Abstract: A switching device is provided for disconnecting or connecting an electric machine, a converter or a plurality of electrical loads supplied with AC power from a power supply and controlled by a control unit. The switching device includes a current sink and at least one mechanical switch in the switching device are arranged in a circuit. The current sink is arranged, upon receipt of a signal, to close and sink the current, and the at least one mechanical switch is arranged to open and break the current on receipt of a signal to open supplied to the electric machine when the current load is at or close to zero. A method and a computer program for carrying out the method are described.

Abstract: A system for operating an electric machine and a method for protecting an operation control unit in such a system. The system includes an operation control unit, an alternating current cable connecting the machine with the operation control unit and an electric short-circuiting arrangement. This arrangement is connected to terminals of the operation control unit facing the cable and short circuits these terminals based on a detected overvoltage.

Abstract: A vacuum circuit breaker for the use in high pressure environments, has at least one vacuum interrupter with at least one moving contact and at least one fixed contact inside the vacuum interrupter, and external contact points at the vacuum interrupter. The vacuum circuit breaker can be used under the high-pressure environmental conditions through the use of at least one vacuum interrupter arranged in a pressure tight container, wherein the electrical contacting is realized via a high voltage bushings through the container wall, and the pressure tight container is at least partially filled with insulating oil.

Abstract: A subsea unit with an external housing, a passive pressure compensator arranged to reduce a pressure difference between ambient subsea pressure and pressure inside the external housing, a dielectric liquid for counteracting deformation of the external housing, an electronic device, and an electrical insulator which is thermally conductive and arranged between an internal surface of the external housing and the electronic device. The electronic device is in thermal and electrical connection with the electrical insulator, and the electrical insulator is arranged to transfer heat from the electronic device to the external housing.

Abstract: A method for monitoring at least one subsea electric machine supplied by a system for electric power transmission. The system has a power supply, a controller and an AC power line connecting the at least one machine with the power supply. The method includes the steps of: receiving at the controller, high speed data from at least one subsea sensor arranged between the subsea side of the AC power line and the at least one subsea electric machine, wherein the high speed data includes measurements of an electrical parameter for the at least one machine; and comparing the one or more measurements to a predetermined value. A system for electric power transmission arranged for operating at least one subsea load or electric machine is also described.

Abstract: A switching device is provided for disconnecting or connecting an electric machine, a converter or a plurality of electrical loads supplied with AC power from a power supply and controlled by a control unit. The switching device includes a current sink and at least one mechanical switch in the switching device are arranged in a circuit. The current sink is arranged, upon receipt of a signal, to close and sink the current, and the at least one mechanical switch is arranged to open and break the current on receipt of a signal to open supplied to the electric machine when the current load is at or close to zero. A method and a computer program for carrying out the method are described.

Abstract: A method for monitoring at least one subsea electric machine supplied by a system for electric power transmission. The system has a power supply, a controller and an AC power line connecting the at least one machine with the power supply. The method includes the steps of: receiving at the controller, high speed data from at least one subsea sensor arranged between the subsea side of the AC power line and the at least one subsea electric machine, wherein the high speed data includes measurements of an electrical parameter for the at least one machine; and comparing the one or more measurements to a predetermined value. A system for electric power transmission arranged for operating at least one subsea load or electric machine is also described.

Abstract: A system for operating an electric machine and a method for protecting an operation control unit in such a system. The system includes an operation control unit, an alternating current cable connecting the machine with the operation control unit and an electric short-circuiting arrangement. This arrangement is connected to terminals of the operation control unit facing the cable and short circuits these terminals based on a detected overvoltage.

Abstract: A drive controller arranged to provide electrical power from a power supply to a machine or load over a long AC power cable of the order of kilometers. The drive controller is arranged with circuits and/or control processes to provide AC current at a constant ratio of voltage and frequency to said machine or load. The drive controller maintains voltage and frequency at the machine terminals despite fluctuations in voltage and/or frequency that would ordinarily be caused by the load. This is done by estimating the voltage and current at the machine terminals and adapting the drive controller output accordingly to actively vary the converter output dependent on the load of the machine or other load. In other aspects of the invention a method and a computer program for carrying out the method are described.

Abstract: A drive controller arranged to provide electrical power from a power supply to a machine or load over a long AC power cable of the order of kilometers. The drive controller is arranged with circuits and/or control processes to provide AC current at a constant ratio of voltage and frequency to said machine or load. The drive controller maintains voltage and frequency at the machine terminals despite fluctuations in voltage and/or frequency that would ordinarily be caused by the load. This is done by estimating the voltage and current at the machine terminals and adapting the drive controller output accordingly to actively vary the converter output dependent on the load of the machine or other load. In other aspects of the invention a method and a computer program for carrying out the method are described.