Why Your Area Might Experience Rotating Brownouts

(SPOT.ph) It’s hot, sticky, and everyone’s electric fans and air-conditioners are likely working overtime. The last thing anyone wants in this weather is a brownout, especially the kind that comes and goes. Why do rotating brownouts happen in the first place?

The answer is simple: demand for electricity can climb too high or available supply can drop too low. When that happens, Meralco said grid operators may have to step in to keep the power system from running into bigger problems.

You may have heard the terms yellow alert and red alert from the National Grid Corporation of the Philippines (NGCP) whenever the grid is under strain. A yellow alert means there is still enough power supply to meet current demand, but reserves have already fallen below the required level. A red alert is more serious: it means supply is no longer enough to meet demand, raising the possibility of power interruptions.

That’s where rotating brownouts come in. According to Meralco, these interruptions are not meant to be random. They are a controlled way of cutting power in selected areas for a limited period so the entire grid does not get overwhelmed.

Also read: What Do Red and Yellow Alerts Mean for Electricity Grids?

According to Meralco, there are usually two big reasons.

First, demand can shoot up, especially during hot days when more people use cooling appliances (guilty). Second, supply can drop when power plants go on outage, operate below full capacity, or face transmission constraints that prevent electricity from being delivered where it is needed. When those happen at the same time, the grid has less room to breathe.

Meralco pointed out that it sources power from power plants to the Luzon Grid, which is controlled by the NGCP, so it does not control whether the grid has enough supply at any given time. Its only role is to distribute electricity within its franchise area.

One of the most frustrating parts of experiencing a brownout is seeing your neighbor’s lights still on. This is because homes, streets, and establishments are not always connected to the same electrical circuit, so one area can be affected while another nearby area is not.

Critical facilities such as hospitals and other essential services may also be prioritized by Meralco.

As for why advisories sometimes come late, Meralco said rotating brownouts often depend on the real-time grid conditions. Utilities may not get much advance notice before they are told to cut power in some locations. This is why advisories can come close to the actual interruption period, annoying as that is for everyone.

"Meralco has no visibility over [power plant] operations. We advise our customers of the brownouts as soon as information on the power supply situation is shared with us by the NGCP, which has the information of the volume that plants in Luzon Grid is able to supply," it said on Meralco's website.

Also read: 10 Rechargeable, Portable Fans to Use During Brownouts