An estimated 850,000 of customers of Manila Electric Co. (Meralco) were affected by the automatid load dropping due to the tripping of a 500 kilovolt transmission line at 6:45 pm Sunday.
Other areas affected included provinces in Luzon, including Metro Manila, Cagayan, Kalinga, Apayao, Laguna, Quezon, Batangas, Camarines Norte.
ALD is implemented by automatically removing pre-selected Loads from a power system in response to an abnormal condition to maintain the integrity of the grid.
“At 6:45pm, a 500kV line tripped and subsequently automatic load dropping (ALD) occurred at NGCP (National Grid Corp. of the Philippines) and Meralco feeders due to tripping of four plants. At 7:33pm, normal operations resumed,” Department of Energy undersecretary Rowena Guevera said when sought for comment.
Meralco issued an advisory to its customers after it implemented ALD in parts of Pasig, Quezon City, Cavite, Manila, among others.
“Some Meralco customers are currently experiencing power interruption after an Automatic Load Dropping (ALD) occurred at around 6:45 p.m,” the power retailer said.
Meanwhile, NGCP said it is investigating the root cause of the grid disturbance.
“At 6:45PM, NGCP monitored a grid disturbance affecting the San Jose-Nagsaag 500kV transmission line 2 and multiple power plants in Luzon and resulting in ALD,” it said.
NGCP said it fully restored the areas affected by the ALD at 7:33PM Sunday.