The National Grid Corporation of the Philippines (NGCP) placed the Mindanao Grid under red and yellow alert status on Tuesday, September 8, due to thin power reserves.

According to the NGCP, a red alert was raised from 1:00 p.m. to 4:00 p.m. and from 5:00 p.m. to 9:00 p.m.

Meanwhile, a yellow alert was declared from 12:00 p.m. to 1:00 p.m., 4:00 p.m. to 5:00 p.m., and 9:00 p.m. to 10:00 p.m.

As of 1:20 p.m., the grid had an available capacity of 2,673 megawatts (MW) against a peak demand of 2,639 MW.

NGCP said a total of 763.6 MW remained unavailable to the grid due to forced outages and derated capacities of several power plants. Ten plants were on forced outage in September, while five plants were operating at derated capacities.

The extension of the red and yellow alerts was attributed to the tripping of Minergy Coal Unit 2, which has a capacity of 50 MW, and an increase of around 100 MW in forecasted system demand.

A red alert is issued when power supply is insufficient to meet consumer demand and the transmission grid's regulating requirements, while a yellow alert is declared when the operating margin is insufficient to meet the grid's contingency requirements.