Leak Sparked City Blackout

Sydney Morning Herald

Wednesday November 3, 1999

By NADIA JAMAL Urban Affairs Writer

Moisture leaking through a cracked seal on a piece of electrical equipment at a Sydney substation triggered the city's worst ever blackout last month, a final report into the incident has found.

The EnergyAustralia report found the 21/2 hour power failure on October 12, traced to an electrical substation at St Peters, was sparked by a ``rare set of events unlikely to occur again".

However, the company yesterday refused to guarantee the system would be free of blackouts in the future.

Last month's power interruption to most of the CBD, Pyrmont and Darling Harbour threw the city into chaos, trapping people in lifts and costing small business owners more than $500,000 in lost sales.

EnergyAustralia said the report had ruled out lack of maintenance as a contributing factor to the interruption.

The company's managing director, Mr Paul Broad, said in the past five years there had been no reduction in maintenance levels for critical functions such as protection systems and zone substations.

But the Electrical Trades Union (NSW) continued to blame the widespread power failure on government cuts to the electricity workforce and maintenance budgets.

The report said the main causes of the disruption were resistor failure, which would have been detected at a maintenance inspection due in late October, a setting error in the protection system which had gone undetected for 12 years, and a relay fault in another cable.

A seal on a porcelain insulator at the substation had split, allowing a few drops of water to reach its oil cavity.

This led to a build-up of pressure in the cavity which caused an explosion that activated an automatic protection system. The system operated ``too conservatively", shutting down a bigger part of the network than it should have. The wider interruption was caused by incorrect settings on two protection circuits.

All 10 resistors of the type that failed were being replaced with a new resistor that was not susceptible to corrosion failure.

``The corrective measures put in place following this unfortunate and unforseen combination of events should greatly reduce the likelihood of any recurrence," the report said.

Mr Broad said he was confident the new measures to improve the network would further reduce the risk of similar interruptions.

But he also warned: ``Murphy's Law always tells me you can't guarantee 100 per cent. We have a number of problems every day in our system."

The deputy secretary of the Electrical Trades Union (NSW), Mr Warwick Tomlins, accused the five major NSW-based electricity distributors EnergyAustralia, Integral, Great Southern, Advance and North Power of ``conditioning the customer" to accept that blackouts would be a normal part of life and warned that customers would face more regular blackouts.

``Why, all of a sudden, are there blackouts occurring all over the place?" he said.

``It's certainly due to a lack of maintenance. None of the distributors have anywhere near the workforce numbers that they previously had and maintenance is done on an ad-hoc basis, and that just isn't enough to maintain the system."