Understanding outages and voltage dips

Definition

A voltage dip occurs when the supply voltage drops below 90% of the standard voltage. Most voltage dips last for around 0.1 sec.

Impact

During a voltage dip, the power supply is not interrupted. However, customers may experience some impacts. For example: 

• Customers' lights may dim or flicker;
• Customers' lift may trip;
• Sensitive equipment may be affected.

Causes

No power system can entirely avoid voltage dips. There are various factors to trigger a voltage dip:

• Adverse weather conditions
• Vegetation, animal, etc. 
• Equipment failure 
• Third party damage
• Cable damage due to excavation

Protecting customers' equipment

Customers should turn off their heavy loading appliances (e.g. air conditioner) when a voltage dip leads to power interruption. For more information, please:

• Refer to our Power Quality Tips; or
• Check out our Power Quality Workshop.

CLP’s responsibilities 

We are responsible for: 

• Generation equipment
• Overhead lines
• Underground cables
• Substations/Transformers 

Customers' responsibilities 

As a CLP user, customers are responsible for:

• The main switch and other switchgears in switching rooms
• Rising mains and switchgears in buildings
• Meter rooms on individual floors
• Switch boxes and circuit breakers