Hydro chief Steve Davy says experts have pinpointed ‘root cause’ of Basslink failure

HYDRO Tasmania says it has solved the mystery of what caused the state’s energy crisis.

THE failure of the Basslink electricity interconnector in December 2015 was caused by the operators exceeding the power cable’s design limit, Hydro Tasmania has claimed.

The cable’s failure — coupled with low dam storage levels — plunged the state into an energy crisis.

Hydro CEO Steve Davy today said an expert report commissioned by the government-owned power generator had identified “issues related to heating and cooling of the cable under operational stress” as the root cause of the cable’s failure.

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The report recommended a short-term export limit of 500MW.

Mr Davy said the limit would not effect the state’s energy security.

“We’re confident this expert investigation solves the mystery of the Basslink failure for all Tasmanians,” Mr Davy said.

Repairs to the Basslink (Bass Link) cable.

“BPL believed its cable could safely and reliably operate at 630MW for extended periods without overheating the copper and insulation and causing an unreasonable likelihood of failure.

“Unfortunately, they were wrong. The expert reports note that the cable, as designed and constructed, cannot meet the minimum operating requirements. “

Hydro’s expert report is at odds with a report commissioned by the cable operator, which found the cause of the outage was unknown.

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“The operating conditions at, and preceding, the time of failure were no different to those of the year of 2015 and the cable was within its thermal rating,” the Basslink investigation concluded.

“The insulation adjacent to the failure site was sound and showed no evidence of thermal ageing. A sample of cable remote from the fault site was in sound condition.”

A company spokesman said it stood by its own analysis of the cause.

“Basslink stands by the independent investigation that was undertaken by Cable Consulting International, one of the world’s leading submarine power cable experts, who described the exact cause of the subsea cable fault as “cause unknown”.

Energy Minister Guy Barnett said the downgrade to the export limit of Basslink would not affect the state’s energy security.

Hydro Tasmania CEO Steve Davy. Picture: LUKE BOWDEN