Precautionary Measures to Mitigate the Impact of Voltage Dips

A voltage dip occurs when the supply voltage temporarily drops below 90% of the standard voltage. Most voltage dips only last for around 0.1 seconds and are caused by various factors. Some external factors include damage to outdoor overhead cables caused by typhoons, lightning strikes or interference from external objects, and damage to underground cables due to excavation.

Impacts of Voltage Dips

During a voltage dip, the power supply is not interrupted. However, customers may be impacted in some ways. For example:

•  Lights may dim or flicker
•  False alarms (e.g. fire alarm) may occur
•  Lift and escalator services may trip due to automated protection control
•  Sensitive equipment may be affected

How to Mitigate These Impacts

Business customers can install an Uninterruptible Power Supply (UPS) to  provide continuous and conditioned power to equipment. It is not affected by voltage fluctuation, voltage dip or loss from input power. Additionally, they can consider equipping machines with automatic restart devices, which helps restore the equipment’s functions after tripping due to a voltage dip. Visit the Power quality tips (clp.com.hk) page to learn more about how to minimise the impacts of voltage dips.