Wednesday, July 27, 2011

Hannover (Germany) Black Out Caused by Aging Infrastructure

Some 600,000 people of the city of Hannover (Northern Germany) were hit by a blackout (up to 81 minutes) on July 13, 2011.

First a power plant was tripped due to some internal problems. Then it was expected that a 220 kV / 110 kV transformer substation would transform more power from the 220 kV network into the 110 kV network – this would have balanced the load in the city and provided power from outside.

The transformer was protected by protection functions that prevent overloading (overheating) the transformer – in order to not damage the transformer windings by too high temperatures … Due to the increase of power flow after the power plant outage in the city, the protection tripped, because it decided that the flow was above the configured limit. The limit was correctly set – but a capacitor (worth a few Euro) was defect and the result was that the protection tripped the circuit breaker even at a current below the configured limit! It would be interesting to know how old the protection relay was.

Due to the aging of the hardware (capacitor) it happened in Hannover recently. What city or region will be next hit by the aging infrastructure of our electrical delivery system?

More to come.

More maintenance (as decided by the utility in Hannover) is not an anti-aging means – refurbishment of aged components of the infrastructures may help … but costs a lot of money.

Click HERE for the press release of the enercity utility of Hannover [German only].
Click HERE for a discussion of aging infrastructures [German only]

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