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Blackout: CEB engineer says multiple tripping prevented early restoration of power
The countrywide power failure this week lasted between six and nine hours because every time engineers attempted to rig various generators to the system, they kept tripping or disconnecting from the grid, a senior engineer said.
“The simple answer is that we tried every protocol we had in place but it kept tripping at some point, many times,” said Susantha Perera, Deputy General Manager (Transmission Design) at the Ceylon Electricity Board (CEB).
The reason for why this happened is yet to be determined.
At least three separate groups — the CEB, a committee appointed by the Power and Energy Minister, and the Public Utilities Commission of Sri Lanka (PUCSL) — are looking into why all of Sri Lanka lost power on Monday after an electrical superintendent carrying out routine maintenance at the Kerawalapitiya substation “forgot to disconnect the earth before switching the supply back on”. The committee report is expected tomorrow.
“He had attended to his maintenance work which requires him to earth the bus bar,” Dr Perera said. “But he has to remove the earth before he puts the supply back. He forgot to do that.”
An electrical bus bar is defined as a conductor or a group of conductors used for collecting electric power from the incoming feeders and distributing them to the outgoing feeders. It is a type of electrical “junction” in which all the incoming and outgoing electrical current meets.
The CEB says the resultant voltage surge caused the coal power plant at Norochcholai to trip or disconnect from the grid. This caused a cascade effect which saw other power plants also trip or disconnect from the grid as their individual protection systems became activated.
However, even in such an event, the utility should have been able to return power within two hours. But it took much longer because, while the CEB followed each of the several protocols in place to restore electricity, the system kept becoming unstable and the generators tripped.
Meanwhile, the CEB maintains that it was the short at the Kerawalapitiya substation that took Norochcholai off the grid but the matter is still under investigation.