Voltage dips 'common' because of exposure to outdoor environment

Stacy Shi

Voltage dips are a common occurrence in overhead power lines due to their exposure to the outdoor environment and susceptibility to external disturbances, power supplier CLP Power said.

These dips, which refer to a drop in supply voltage below 90 percent of the standard voltage, are primarily caused by factors such as extreme weather conditions, interference from tree branches and construction work near power lines.

CLP has reported nine voltage dips in the previous year and three within the first four months of this year.

While power outages result in a complete interruption of the power supply, voltage dips do not lead to a loss of power.

However, during a dip, certain effects can be observed, such as the dimming or flickering lights, activation of fire alarms and potential disruptions to electrical installations and sensitive equipment, saidMichael Lau Ho-yin, north region power systems director at CLP Power.

"For instance, lifts and escalators may be temporarily suspended due to the activation of protective devices," Lau said.

Lifts installed after 2009 are equipped with automatic resumption devices that allow them to resume operation once normal voltage levels are detected. "In cases where lifts lack automatic resumption devices, the building management must seek assistance from qualified elevator workers to reactivate them or consider installing additional equipment, such as Uninterruptible Power Supply devices, to achieve the same effect," Lau added.

To address these issues, power companies like CLP have established professional advisory teams to assist customers and building owners' corporations.

CLP has taken measures to mitigate voltage dips, including installing lightning arresters at main power facilities to minimize the impact of lightning strikes, as well as conducting regular inspections of power lines and construction sites.

Regarding penalties for sudden voltage dips, CLP acknowledged the public's desire for improved power supply stability and said "the priority at this stage is to engage closely with key stakeholders with a view to identifying a solution that will minimize the impact of sudden voltage dips."

Meanwhile, CLP has a dedicated team responsible for timely tree trimming to prevent interference between trees and overhead power lines, ensuring a minimum distance of nine to 12.5 meters between the cables and trees.

stacy.shi@singtaonewscorp.com