MANILA, Philippines: The Luzon grid is on yellow alert while that in the Visayas is back to normal, the National Grid Corp. of the Philippines (NGCP) announced on Saturday.

In a Facebook post, the NGCP said the Luzon alert was prompted by the "forced outage" on 22 power plants and one running on "derated capacity."

As a result, the NGCP said "a total of 2,325.8MW was unavailable to the grid."

The Luzon grid's capacity as of 7 p.m. on Friday was at 12,048 megawatts (MW) while the peak demand was at 11,426 MW.

Saturday's yellow alert takes effect from 6 p.m. to 10 p.m. the NGCP said.

The NGCP said a yellow alert is issued "when the operating margin is insufficient to meet the transmission grid's contingency requirement."

The NGCP on Friday lifted the alert for the Luzon grid, before its advisory this Saturday.