Three out of the four installed 8315kVA transformers all suffered similar significant electrical failures, due to environmental conditions. This placed the production of the vessel at risk as these transformers were used to feed HSP Power Water Pumps.

The three units, totalling around 50T in total, were delivered to TDC Parsons Peebles in Rosyth for evaluation and the development of a repair and test plan for a best possible recovery situation. One unit remained energised on the FPSO, and the requirement was to make one serviceable transformer from the three failed units as quickly as possible.

Each of the transformers were removed from their respective enclosures and a series of investigate tests and inspections completed. We concluded very early that one unit could be made serviceable in a short timescale . After more extensive work on the second unit to be repaired, the third unit became the ‘donor’ for many parts which were beyond repair due to arc and flash damage.

After completion of the testing, the head laminations of each of the transformers were removed from the limbs, to allow coil removal. Further testing was completed on each of the individual windings and repairs made to the copperwork carried out as required. The limbs and steelwork were all cleaned to remove the flash and carbonisation damage. New insulation at top and bottom of each limb was fitted. Insulation wraps were all replaced along with the glass laminates spacer rods. Coils were then all re-fitted to the limbs. The head laminations were all hand cleaned and then reinserted to complete this tranche of the project.

Once all the connections were made, the units were put into our test area. We worked with the original manufacturer to ensure we duplicated the test procedures for each of the transformers. Tests included Winding Resistances, Voltage Ratio & Phase Displacement, AC Withstand Test, Induced Overvoltage withstand Test & Insulation resistance.

Upon successful testing the transformers were refitted to their respective enclosure, final static tests were carried out before being shipped back to the FPSO for immediate installation.