Load shedding, load rotation and load limiting – what’s the difference?

City Power announced that certain Joburg suburbs would be subject to load rotation on Friday morning, sparking fears that load shedding would be on the cards once again.

Load shedding made an ugly return to South African metros over the last month, after striking workers sabotaged the national grid, forcing maintenance backlogs and halting power production.

In simple terms, load shedding happens when Eskom’s power supply cannot meet demand due to a constrained grid, and the company shuts down power in a controlled manner (on a schedule) to prevent a complete grid blackout.

While the threat of load shedding is ever-present, Eskom has said it is doing everything it can to keep the lights on. However, with winter setting in, and cold fronts expected to sweep the country in the next week, the risks remain high.

Load rotation, as announced by City Power, is a similar process, but on a more localised level, and is not on a schedule – ie residents experience unplanned outages.

Load rotation takes place when there has been a transformer failure at substations or when demand exceeds supply and the systems trips. Power providers like City Power are forced to restart the system for affected areas one by one to ensure the trip doesn’t happen again.

If the power trips again, the entire process needs to be repeated.

According to City Power, load rotation was implemented due to increased demand on the system. No transformer failures were mentioned by the supplier. If a transformer was damaged, the remaining supply points would have to manage the demand until repairs are made, which is why the load is rotated among affected areas.

The final term to be aware of is load limiting, which is when smart metres will switch off your power temporarily to warn you to cut back on your current power usage. It’s a process used to prevent load shedding.

During a load limiting session, electricity will go off for approximately 30 seconds, but will then come back on for an additional 30 seconds before switching off again.

In this time consumers should then switch off some of their appliances, including geysers and underfloor heating, pool pumps etc, to reduce the load to at least an acceptable limit that will help avoid load shedding.

Read: Eskom warns over long term load shedding

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Load shedding, load rotation and load limiting – what’s the difference?