An LOR3 is the highest level of alert, indicating there are no reserve power supplies available.

The most recent LOR3 forecast was issued by EvoEnergy for the ACT in January 2020, at the height of the Black Summer bushfires as fire threatened major supply towers and lines to the territory.

EvoEnergy said that due to commercial confidentiality, it would not disclose the major power consumers to which it had provided an alert.

The national energy market operator (AEMO) describes LOR3 as "a deficit in the supply/demand balance" in which "controlled load shedding may be required as a last resort to protect system security and prevent long-term damage to system infrastructure".

Queensland avoided load shedding on Sunday evening through market intervention, and the same occurred in NSW on Tuesday.

While the ACT has no heavy industry, it is part of the NSW network and as such would be required to absorb a proportion of the load shedding required.

Generally avoided by power companies are "sensitive" loads such as major hospitals, central business districts and public transport where the loss of electricity would present a serious risk to public safety. Load shedding can be managed voluntarily and can be staggered in time intervals between major users, with residential shedding as a final resort.

Federal Energy Minister Chris Bowen said that in his discussions with AEMO on Tuesday, he was confident that "the situation can be and will be avoided in NSW and Victoria in the coming days".

The lingering uncertainty which remains and which has the energy operator cautious, is the possibility that any of the base load power generators may go offline. With no reserve capacity, the operator would then forced to intervene quickly and turn down network distribution to avoid systems damage.

Minister Bowen was eager to cool the speculation of this occurring, saying there was has "enough reserve in the system to avoid those [blackouts] for the foreseeable future".

He said that AEMO would "as a matter of course" be talking to the very large industrial users about the situation, asking them what they can and will put in place.

In a market notice issued at 4.10pm on Tuesday, AEMO stated that it had "entered into a reserve contract and may implement [an] Intervention event by dispatching that reserve contract to maintain the power system in a secure and reliable operating state" from 5pm on Wednesday.

Under Chapter 4, Clause 8.3 of the National Electricity Rules, AEMO is required to publish all relevant details promptly when it becomes aware "of any circumstance with respect to the power system", which may include "electricity capacity supply shortfall", "unexpected disruption of power system security" or a "major supply disruption".

The operator also has the power to direct distributors, such as EvoEnergy, to "do any act or thing ... necessary to ... maintain or re-establish the power system to a secure operating state, a satisfactory operating state or a reliable operating state".

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