Why brownout occurs?

LAOAG CITY, July 5 – The sudden occurrence of automatic load dropping (ALD) caused widespread power outages in all provinces in the Ilocos region including some areas in Metro Manila early evening last Tuesday.

The automatic load dropping occurred due to insufficient power supply in the transmission lines, which eventually led to power shut down in some areas, according to Ilocos Sur Electric Cooperative (ISECO) General Manager Egdon Sabio.

“Unfortunately, the deficit in power supply was equivalent to the power supply for the provinces of Region 1 and some parts of Metro Manila,” he said. “Thus, we were affected by a sudden brown out.”

The National Grid Corporation of the Philippines (NGCP) restored power after 30 minutes up to two hours in some areas.

Sabio said the NGCP is the only entity responsible in looking for power generators that would help augment the needed power supply for power restoration.

Meanwhile, the NGCP advisory said brownouts occurred when the Pagbilao – Tayabas Lines 1 and 2 tripped-off at 6:34 pm on Tuesday and went offline causing 1,000 megawatt of power load to be dropped from the grid.

“The power interruption in various areas in Luzon areas was due to system under frequency,” NGCP said in a statement.

The Department of Energy (DOE) also reported that three power plants suddenly shut down causing power to trip–off affecting the Luzon grid last Tuesday. The power plants include the Sta. Rita, Pagbilao and Quezon. (Freddie G. Lazaro)