RSA Power Company (Eskom) wrecks 600MW Turbine in Overspeed Test

[sshep]

My Friends,

After a low key press release in South Africa last month, the full extent of the aftermath of a bungled turbine overspeed test at South Africa's national power company (Eskom) is becoming obvious from pictures on the internet. In a country with a serious electrical shortage, the loss of 600MW of capacity is a severe blow. The pictures tell it all.

This led to a comment from a peer that electrical overspeed protection is superior to mechanical protection because the testing can be done without actually running the turbine to the overspeed trip point. Although I agree that some components of the protection system can be tested like that (partial testing), a full test seems like it would still need to be done under actual overspeed conditions, so I am not convinced that electronic protection is fool proof either. Are there any comments on overspeed protection and testing?

best wishes,
sshep

http://www.intranews.co.za/clipping...ell a thousand words about operator error.pdf

http://files.engineering.com/getfil...-8bc5-4fcd-8613-8d8c189a6bfb&file=Duvha_1.jpg

http://files.engineering.com/getfil...-a3a2-4fd9-97ce-5e2eeeb1fbc0&file=Duvha_2.jpg

http://files.engineering.com/getfil...-8641-4845-ac83-ebd404e56113&file=Duvha_3.jpg

 

[unclesyd]

Definitely a hand grenade.
I on e heard an operator ask another one was the unit broke and receives the following answer "broke, broke bad.

I jsut check out the powerhouse, three small turbo generators, and no one call recall ever running the units to the over speed trip.
The governors are sent overhauled and calibrated every year. If I recall correctly there are redundant trips for the unit. It will trip on over speed if the grosvenor fails, any vibration above background with trip the unit, there is also a warning given by a vibration monitor in the frame, High steam flow or variable pressure.
The last time I was involved with units where surge had sheared the "distance rings" in one of the steam turbine. I had the shop make a replacement from a large RTJ gasket. During one of the several meetings on the subject there was a suggestion to replace the Woodward Governor Vales with knock off brand. The poor fellow was nearly booted out of the meeting.

 

[dcasto]

To add insult to the injury

A similar incident happenned at this same power station in 2003.

http://www.massengineers.com/generator_accident_in_africa.htm

http://www.mg.co.za/article/2011-03-18-power-plant-blast-threatens-supply

 

[MikeHalloran]

Maybe they haven't had time to actually read the (promised) inquiry report from the 2003 incident. Anyone have a copy?



Mike Halloran
Pembroke Pines, FL, USA

 

[KiwiMace]

The leaked photo blurbs and article just reek of someone covering their derriere, and pushing blame solely to operations. Surely the safety mechanisms are individually tested before such a thing takes place. There looks to be a maintenance shortfall, which so often stems from a maintenance budget shortfall.

I agree that it looks to have got wildly out of control and someone should have been ready to shut the thing down.

 

[ScottyUK]

sshep,

Some discussion of turbine OST types in thread666-289692

Thanks for the link to the SA incident.


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