What are the causes of brownouts?

1. Scheduled Power Interruptions

Maintenance Activities of Power Suppliers

DORECO is dependent on power suppliers like Therma South Incorporated (TSI) which supply electricity to Davao Oriental. These power suppliers occasionally stop for repairs and maintenance.

The duration and restoration of these power interruptions cannot be controlled by DORECO, but DORECO announces these a few days before the scheduled interruption.

Maintenance Activities of NGCP

DORECO is also dependent on the National Grid Corporation of the Philippines (NGCP) which transmit electricity from power suppliers to Davao Oriental. NGCP also occasionally stops for repairs and maintenance.

The duration and restoration of these power interruptions also cannot be controlled by DORECO, but DORECO announces these a few days before the scheduled interruption.

DORECO Scheduled Interruptions

Electric service is cut off at designated areas for a definite period so that repair crews can do maintenance work and upgrade distribution facilities like high-tension wires, poles, transformers, etc.

These are necessary to improve service reliability in the distribution system. These are usually announced a few days before the interruption.

2. Unscheduled Power Interruptions

Man-Made Accidents

Brownouts occur when an electric post and other electric facilities are hit by a motor vehicle or other mechanized equipment, when construction materials fall on power lines, or when kite strings get entangled with power lines. These incidents will cut distribution wires and cause power interruption.

Fires and Floods

Fires and floods are emergency situations that make it necessary for the electric cooperative to shut off power temporarily in the affected areas for public safety.

Thunderstorms and Typhoons

When lightning hits electric wires, transformers or substations, widespread power interruptions will ensue. Thunderstorms and typhoons can cause substantial damage to distributions facilities resulting in extensive and prolonged service interruptions.

Trees and Vegetation

During strong winds, intermittent interruptions are often caused by branches of trees, vines, coconut fronds, or bamboo plants momentarily touching bare high-tension wires. At worst, the power lines may burn and fall to the ground.

Sabotage and Pilferages

There are band elements of society who are out to sabotage the country’s economy thru pernicious means. One such practice is sabotage and pilferages of NAPOCOR’s transmission lines particularly those traversing mountain ranges in the countryside.

What the saboteurs and pilferers are doing is they damage the transmission towers by blasting, sewing off and stealing the tower parts or causing the whole tower to fall and stealing the aluminum cables. A brownout or black out is triggered once the lines are damaged.

Short-Duration Power Cuts

Sometimes, short-duration power cuts are caused by Automatic load dropping (ALD). ALDs occur when a large chunk of power generation is instantaneously removed from the grid causing the system frequency (normally at 60 hertz) to dangerously drop, unless an equivalent amount of power loads is also removed from the system.