MANILA — The National Grid Corporation of the Philippines on Tuesday placed the Luzon grid on yellow alert, the second highest warning, due to low reserves.

The alert was raised from 11 a.m. to 5 p.m. and will be in place again from 7 p.m. to 9 p.m., the NGCP said in a Facebook post.

The unexpected shutdown and limited generation of some power plants led to low reserves, with peak demand at 9,491 megawatts against available capacity of 10,115 megawatts.