The Luzon grid was placed under yellow alert for four hours on Tuesday with several power plants on a forced outage, the National Grid Corporation of the Philippines said.
A yellow alert warning means power reserves are low but does not necessarily lead to brownouts. A red alert, one notch higher, means demand is higher than supply which could lead to rotating brownouts. When there is sufficient supply, the NGCP uses the white alert.
For Tuesday, the NGCP raised the yellow alert from 10 a.m. to 11 a.m. and 1 p.m. to 4 p.m. since the available power capacity is at 11, 847 megawatts, slightly above the operating requirement of 11, 177 mw.
Privately-owned NGCP announces alert notices since it links power generators to distribution utilities.
In the case of the Philippines, the Luzon grid generates the most power compared to the Visayas or Mindanao grid.