Abstract:
The Petrobras Gas Plant, located in the state of São Paulo in southeastern Brazil, receives and processes all the gas from the platforms associated with Rota 1 in the Santos Basin, including gas from the Pre-Salt and Post-Salt reservoirs. To provide electrical power to the plant, which is not connected to the grid, four synchronous generators (37.5 MVA, 1800 rpm, 13.8kV) driven by gas turbines are utilized. All the energy used in the gas processing unit is generated internally.
In July 2022, the IRIS Power partial discharge monitoring system was installed on the generators, incorporating 80pF capacitors, and the portable partial discharge collector model TGA-B was acquired. Since the system’s activation, one of the generators (TAG: GE-513201D) has exhibited significant levels of partial discharge activity.
Initially, the predictive maintenance plan for the generators, which included partial discharge monitoring, called for semi-annual data collection. However, with the acquisition of the portable system and the identification of the defect, the collection frequency was adjusted to biweekly in order to closely monitor the machine’s condition and extend its operational lifespan until the next scheduled plant turnaround.
During the maintenance shutdown in 2024, a major intervention was carried out on the equipment, involving a complete disassembly and rotor extraction. With the generator disassembled, it was possible to locate the defects in the winding responsible for the high levels of partial discharge activity and rectify them on-site.
The results demonstrated the crucial role of the offline partial discharge system in monitoring the equipment’s condition and scheduling the maintenance shutdown at a more suitable time for the plant, thereby mitigating the risks of production loss.