[bert]

The guri dam has lots of turbines......Francis Turbines. 10 × 730 MW
4 × 180 MW
3 × 400 MW
3 × 225 MW
1 × 340 MW

The power station had a combined installed capacity of 1750 megawatts (MW).[3] By 1978, the capacity had been upgraded to 2065 MW, generated by ten turbines.

Because the electricity demand grew so fast, 1976 saw the beginning of a second building stage: a 1300 m long gravity dam was built, another spillway channel and a second powerhouse containing 10 turbines of 630 MW each.
**************

Since there are numerous turbines in at least two power houses, we must deduce that the problem is not a single turbines. The wiki article notes that the entire operation is controlled by a computer system designed by Hitachi. The problem lies beyond the turbines and is likely the gris/generator controlling Hitachi system.

The Wiki article is current

https://en.wikipedia.org/wiki/Guri_Dam

[Captain Peter Blood]

I would make a guess that the reason the lights are out is that basic maintenance has been neglected over a long period of time and that will lead to major problems and this is it.

It could be years before those plants are in operation again regardless of what happens.

[Kommodor]

-— the capacity had been upgraded to 2065 MW

2.1 Gigawatts??? Great Scott!

(I know, not quite right, but hey)

[Spktyr]

Mismanagement and idiocy can easily cause a single event to destroy multiple turbine generator sets. Doesn’t have to be the computer controls - and remember that most of the competent people have already fled.

Russia recently had a mechanical failure in a single turbine that took out the entire station’s power output: https://en.wikipedia.org/wiki/2009_Sayano%E2%80%93Shushenskaya_power_station_accident

[Spktyr]

Also, there have been a *lot* of problems with Francis turbines of late: https://phys.org/news/2015-05-hydropower-turbine-failure.html

[catnipman]

yeah, i checked that wiki article out too ...

gens could have been irreparably damaged if not shut down quick enough after suddenly losing their load, say if the main transmission lines and/or main substation suddenly failed ...

a combination of sensors and computer control systems would have had to react very quickly to shut down those gens under such circumstances. those kinds of systems would be somewhat delicate and would have had to be continuously and properly operated, tested, maintained, repaired and replaced ...