When there is not enough supply capacity available to meet the demand of all customers. It could be necessary to interrupt the power supply at an interval to certain areas.
However, if supply is interrupted without notice of load shedding, or not as per the load shedding schedule. It is more likely that the outage is caused by some other reasons including cable theft or technical problems.
Load shedding is only applied when other voluntary and contracted demand reduction has been exhausted in other to avoid a total collapse of power supply.
By rotating and shedding the load in a planned and controlled manner, the system remains stable.
If load shedding is required, the National System Operator instructs the stakeholders on the stage that is to be shed.
The duration of load shedding will depend on specific supplier, region, and circumstances.
Situations that May Lead to Load Shedding
- Coal supply or handling
- Generation problems
- Demand prediction error
- Weather-related issues
- Supply import problems
Critical Loads that are Protected
Critical loads are loads that are protected from load shedding because they either maintain the operational integrity of the power system or impact on public infrastructure.
- the exclusion of load shedding schedules
- installation of backup facilities
- implementation of specific protocols for interaction between the customers and the licensee.
Examples of Critical loads
- Public transport
- water pumping
- Portable water supply to the public
- Sewage system
- Refineries and fuel pipelines
- Coal mines that supply power stations
- Telecommunication infrastructure
- Traffic lights
System Operator Response
Before load shedding is applied the following levers are exhausted
- All available generations
- Contracted and voluntary demand reduction options with large customers.
If all these options have been exhausted and demand still cannot be met, the National System Operator will proceed with load shedding.