3 ms·

My vague understanding of a turbine was that it was a spinning magnet, so if you killed the circuit it would just... spin, I guess. If this is a concern, why i

by chris_7 10y ago

My vague understanding of a turbine was that it was a spinning magnet, so if you killed the circuit it would just... spin, I guess. If this is a concern, why isn't there a worry that ISIS or just a stray bomb would kill the power lines when retreating from Mosul? Though I suppose they could just target the dam itself...

cesarb 10y ago
> My vague understanding of a turbine was that it was a spinning magnet, so if you killed the circuit it would just... spin, I guess. The load in the circuit acts as a brake. If you kill the circuit, the turbine spins faster and faster until it breaks into pieces. To prevent that, the control systems stop the water from flowing into the turbine, but stopping the water from draining is the opposite of what they want.
- PietdeVries 10y ago
  The story suggests there is a 300 foot wide canal that can be used to let water go in casse of an emergency. Well, how about doing so now? Rather than using the turbines, use the canal to let the water out, but without it generating electricity...
  - takk309 10y ago
    The emergency spill way is in case of a large rain or melt event that brings the water level up quickly. The spill way is used to ensure that the dam is not over topped, which is usually catastrophic. As such, the spill way is usually placed at or near the maximum safe free board (distance from the top of the dam down to the water level). What this all means is that the spill way can only be used when the water level in the reservoir is allowed to get to high and possibly dangerous levels. The article stated the the water level has already been decreased by 10 meters which means that the spill way is going to remain dry for a long while. Next time you are near a dam look around and you will find that most have three paths for the water to leave the reservoir. The first is through the power generating turbines, second is the sluice gates which control water level, and third is the emergency spill way which is designed to fend off catastrophic failure.

by chris_7 10y ago

cesarb 10y ago

> My vague understanding of a turbine was that it was a spinning magnet, so if you killed the circuit it would just... spin, I guess. The load in the circuit acts as a brake. If you kill the circuit, the turbine spins faster and faster until it breaks into pieces. To prevent that, the control systems stop the water from flowing into the turbine, but stopping the water from draining is the opposite of what they want.

PietdeVries 10y ago
The story suggests there is a 300 foot wide canal that can be used to let water go in casse of an emergency. Well, how about doing so now? Rather than using the turbines, use the canal to let the water out, but without it generating electricity...
- takk309 10y ago
  The emergency spill way is in case of a large rain or melt event that brings the water level up quickly. The spill way is used to ensure that the dam is not over topped, which is usually catastrophic. As such, the spill way is usually placed at or near the maximum safe free board (distance from the top of the dam down to the water level). What this all means is that the spill way can only be used when the water level in the reservoir is allowed to get to high and possibly dangerous levels. The article stated the the water level has already been decreased by 10 meters which means that the spill way is going to remain dry for a long while. Next time you are near a dam look around and you will find that most have three paths for the water to leave the reservoir. The first is through the power generating turbines, second is the sluice gates which control water level, and third is the emergency spill way which is designed to fend off catastrophic failure.