The Energy Regulatory Commission (ERC) has begun its investigation into the unplanned shutdown of seven power generators that resulted in the Luzon Yellow Alert on Saturday night.

Based on a Manila Bulletin report, the ERC has required the power plants’ owners and operators to explain the cause of the outage and when the plants would be able to resume providing power to the Luzon Grid.

Power generators that went on unplanned outage include CBK Power’s 720-megawatt (MW) Kalayaan hydroelectric power plant, Unit 1 of Aboitiz Power Corporation’s GNPower Dinginin coal-fired power plant (

668MW), Semirara Mining and Power Corporation’s Sem-Calaca Unit 2 (300MW) and Southwest Luzon Power Generation Corporation (SLPGC) Units 2,3, and 4 (200MW), and Unit 2 of ACEN’s South Luzon Thermal Energy Corporation coal plant (123MW). 

Based on the ERC’s initial report, GNPower Dinginin tripped on Friday (March 25) at 1131PM due to a “turbine balancing adjustment.” Luzon’s largest power generator was able to resume supplying electricity to the grid the following day.

Meanwhile, SLPGC Unit 2 tripped because of “primary air fan A trouble” while Unit 3 and 4 encountered “turbine lube oil sump metal chips.” 

SLTEC Unit 2 encountered high HP relative expansion, while Kalayaan went offline because of “low water” elevation, and the Sem-Calaca facility encountered a generator stator ground fault. 

Including the 823MW derating of four generators, the Yellow Alert shaved off 2,834MW from the grid. However, the Department of Energy downplayed it, saying there is “still enoug

h capacity in the system as it did not result [in] any power interruption.”