NEW TESTING METHOD FOR LARGE HIGH SPEED INDUCTION MOTORS

Large high speed induction motors are being utilized more and more in the Oil & Gas industry to drive compressors. These machines are of particular interest for offshore installations as they significantly reduce the installed foot print. Due to the specific needs of offshore construction and commissioning programs, it is very important for the end users to validate as much as possible the drive systems during tests at manufacturers shop. These motors range from 1 to 20MW, running at speeds between 6,000 and 20,000rpm and are generally equipped with active magnetic bearings. They are always fed by an Adjustable Speed Drive (ASD). In order to test these motors at full power and full speed a new test procedure has been developed and used on several machines from 1.7 to 9MW running around 15,000rpm. A testing configuration has been designed and implemented. The motor to be tested is coupled via a special coupling and a thrust bearing to a high speed induction generator. In order to be as close as possible to the site conditions, the project transformer, Voltage Source Inverter (VSI) and output filter are utilized on the test floor and used to feed the motor to be tested. This paper describes the test configuration from both an electrical and mechanical perspective. Test results are presented to show a full validation of motors characteristics and behavior allowing fast, surprise-free, commissioning on site. The challenges associated with these tests are also presented and discussed.