ABB has designed a system that uses an underwater cable to connect a pump motor on the floor of the North Sea to a frequency converter on an oil platform 31km away. This system has passed a string test for the Tyrihans oil field, off the coast of Norway. Production at the Tyrihans oilfield will employ five subsea skids installed on the seabed 300m underwater. One of them will use a 2.5MW pump motor to inject raw seawater into the oil reservoir, raising pressure in the field to facilitate oil extraction. Tyrihans will deliver oil and gas by pipeline to the existing Kristin oil and gas platform 31km away. An ABB ACS1000 frequency converter installed on the platform will ensure the pump motor at the extraction site runs at optimal voltage. In addition to the unusual pump motor-converter connection, ABB is also supplying the biggest subsea transformer it has ever delivered for the injection skid on the sea floor. For the Kristin platform, ABB will supply specially designed transformers, frequency converters and a controller with software to power subsea motors, and ensure optimal operation of the injection pumps. The subsea cable and platform equipment will be installed in 2009-2010.