Monday's power outage was complicated. At least, there is a very complex version of what happened, and it is below for the bright sparkies amongst us, but lets start with a simple explanation.

The outage was a culmination of high voltage faults that resulted in a forced blackout. The reason for the blackout was to protect the integrity of our electrical network.

Essentially, at around 5.20pm last night, the electricity towers or transmission lines coming to Lismore from Coff Harbour had a fault and tripped out of service. So no electricity from the south.

Then at around 6pm, the power supply from Qld in the north started acting up and couldn’t be relied on.

This meant that Lismore and surrounds, in the middle of what is considered the evening peak supply, had a markedly reduced ability to get enough power to facilitate all our electrical needs. 

What happens when the demand surpasses the ability to supply in the electrical network, there is a danger of stressing critical infrastructure which can put this infrastructure at risk of damage. 

The damage caused to that infrastructure by this scenario means long term outages and disruption to electricity supply in that area. Hence the reason why the decision was made to disconnect the electricity to large areas of the Northern Rivers. 

By around 7.45pm, our electricity demand was sufficiently lowered, so supply was able to be restored in stages. By 8pm, most areas were back to normal, and by 10pm, supply was restored throughout the region.

Now we jump to understanding our electrical supply - how it gets to us and by whom.

We get our power from the power supply companies of which there are a few. The power comes to us on the low voltage network of powerlines that Essential Energy is in charge of.  

The high voltage power in NSW is taken care of by a company, Transgrid. The high voltage power that comes to us from Qld, is controlled by another company, Directlink.

Over the top of all of this, the Australian Energy Market Operator or AEMO undertakes overarching research and decisions that connect the web of power across all of Australia.

So the current status of our electricity supply is: 

Transgrid’s transmission line to the south is currently having the fault repaired, and will be back on line around Thursday. 

Directlink’s unreliable transmission line (called the interconnector) was repaired on Tuesday by around 2pm, so we are now running on a steady supply from the north.

The AEMO considers this a serious breach of electricity supply, and are doing an investigation into the occurence, with a report available in a week or so.

So for those that now have done NSW Electricity 101, here is the actual statement that was originally provided as explanation for the outage on Monday night:

“From 18:17 yesterday, AEMO instructed NSW’s transmission operator Transgrid to shed a total of 40 megawatts (MW) of electricity supply near Lismore in response to issues threatening power system security.

“Earlier that day (05:11), Transgrid’s 330 kilovolt Lismore - Coffs Harbour transmission line tripped and remained out of service. At the same time, the nearby QLD-NSW HVDC interconnector, Directlink, tripped as per design and subsequently returned to service.

“During the evening, Directlink was unable to follow dispatch targets, further limiting the available options to supply power to the Lismore area to meet the evening demand, putting the secure operation of the power system at risk.

“After load shedding had commenced at approximately 18:34, Transgrid’s 132 kilovolt Armidale - Koolkhan transmission line tripped and reclosed, and at the same time Directlink tripped and remained out of service.

“At 19:45, electricity demand reduced, allowing the majority of power supply to be restored by 20:00, with full restoration by 22:00.”