Voltage transformer explosion at Torrens Island nearly caused statewide blackout
Mar 2017Published 19 Oct 2026Responsible editor: Chief Editor
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What happened
On 3 March 2017 a voltage transformer exploded and caught fire in a switching yard at Torrens Island, in Adelaide's north-west suburbs, South Australia. The explosion tripped generators at the Torrens Island and Pelican Point gas-fired power stations, removing 610 MW of generation from the state grid. The sudden loss caused a voltage disturbance, but no load-shedding order was issued. South Australians were asked to moderate their power use until both stations restarted.
The Australian Energy Market Operator (AEMO) recorded an unexplained 400 MW drop in demand, which it believes may have occurred as rooftop solar systems tripped during the disturbance and then reconnected. AEMO's report said the state's power system was not in a secure state for 40 minutes. Flow on the Heywood interconnector rose from about 500 MW to 900 MW, above its design capacity of about 650 MW, and came close to tripping. AEMO said a trip would have caused a statewide blackout.
Contributing factors
AEMO said the interconnector was drawing power near its peak capacity when the generation loss occurred. The rate of change of frequency was attributed to the low amount of conventional generation remaining online after the event and the resulting low inertia. AEMO believed the automatic load-shedding rotation would have been beyond its capability to respond to such a rapid change. Protection settings changed after the September 2016 statewide blackout would have allowed the interconnector to be lost had they remained as they were. No storm was present during this incident.
Lessons learned
- Review changes to protection settings for their effect on interconnector loss under high-flow conditions before and after any scheduled upgrade.
- Monitor interconnector flows against rated limits, because operating close to peak capacity leaves little margin when a generation source trips.
- Maintain sufficient conventional generation online to preserve system inertia, and assess how distributed rooftop solar disconnection may distort demand measurements during a disturbance.
More lessons on electrical protection and isolation, detection and monitoring, from every incident on the register.
Published 2026-10-19. Written from public reporting. Descriptive, not investigative. See the data accuracy disclaimer.
