MANILA, Philippines—(UPDATE) Power supply in Luzon is expected to be fully restored by Sunday, after the onslaught of tropical cyclone Santi (international codename: Mirinae)damaged electrical equipment, wires and transmission lines in several provinces and Metro Manila.

"Based on field reports we are receiving, we expect to reach a state of normalcy by Sunday," said Alex Evangelista, a senior assistant vice president of Manila Electric Co.

As of 6 p.m. Saturday, the distribution utility said that around 445,000 of Meralco's 4.6 million registered customers were without power—down from the 1.6 million customers initially rendered without electricity by Santi’s Passage.

"Felled trees, downed poles and wires, damaged electrical equipment and other debris that hit our facilities were the reasons behind the outages," said Meralco external communication manager Joe Zaldarriaga.

The power distribution utility said it was conducting power restoration work in affected areas, after typhoon Santi hit Metro Manila and other parts of Luzon Friday night and early Saturday.

"In this regard, we are appealing to local government officials, barangay officials, the Department of Public Works and Highways and Metro Manila Development Authority to speed up restoration work. We have to clear the lines of debris and other unsafe obstructions before putting back power to ensure public safety." Zaldarriaga said.

"Please be assured that our personnel are on full complement, and are working round-the-clock to quickly restore power to your homes and businesses," Zaldarriaga added.

Meanwhile, the National Grid Corporation of the Philippines said that as of 4 p.m. Saturday, it had restored and energized all the transmission facilities affected by Typhoon Santi in North Luzon, except for the 20-megavolt ampere transformer unit in Beckel Substation, which had yet to be energized.

According to NGCP, the transformer was still undergoing technical testing as of 5 p.m.

"Once operational, it will be able to deliver electric power to Benguet Electric Cooperative 1 and 2 (Beneco 1 & 2) which in turn provides power to Camp John Hay, Tuding, Kias, and Pacdal in Benguet Province," the private consortium added.

Meanwhile, in South Luzon, NGCP energized the Kalayaan-Gumaca230-kiloVolt (kV) Lines 1 and 2 as well as the San Jose-Tayabas 500-kV line in Quezon.

In Batangas and Cavite, all transmission lines, including those lines rated at 69 kV and directly connected to distribution utilities, were completely restored at 3:21 p.m. Saturday, NGCP said.

"NGCP assures its customers that restoration works on the remaining damaged lines in South Luzon are in full swing. Line crews and system operations personnel are working to immediately bring back power to distribution utilities and other customers which are directly connected to the grid," the company said.

The major transmission lines that tripped due to the typhoon included the Labo-Naga 230-kiloVolts (kV) line 1, Gumaca-Labo 230-kV line 1, Kalayaan-Gumaca 230-kV lines 1 and 2, San Jose-Tayabas 500-kV line 2, Kalayaan-Calauan 230-kV line, Kalayaan-Makban 230-kV line, Kalayaan-Malaya 230-kV line 1, Sucat-Araneta 230-kV line, and Sucat 115-kV tie line.

"Two transformer units at the old Sucat Substation (were) shut down when a portion of the substation was flooded. The shutdown directly affected the franchise area of Meralco in Metro Manila," NGCP reported.

Due to the tripping of NGCP's transmission lines as well as the sub-transmission lines operated by distribution utilities, the current load of the Luzon grid was reduced to only around 50 percent of a typical Saturday load.