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That driveshaft wasn't part of the valve, the water flowing through the valve turns that shaft to generate electric.

It's easy, no use plc. The system is valve bypass, MIV Main valve, PHU - Power Hydraulic Unit of oil, contacts for Open, Close, shut down. Before Check pressure of PHU Open valve Bypass Check pressure in each face of MIV. Open MIV, time of Open is in ramp slowy. Close valve bypass. -work turbine In normal stop of turbine the MIV can Open In shut down the turbine the MIV Close join with gate in pipeline

if Open MIV before bypass valve, MIV NO OPEN, because de differential pressure in the sides of MIV. Bypass valve, firts Open for equalizer pressure.

On a pump-turbine if you lose connection under load the rotor accelerates and the centrifugal forces in the impeller reverse the flow and effectively act like a closed valve, Weight is added to the rotor to reduce acceleration and the inlet valve is closed quickly but not to quickly

@@melaniecotterell8263 interesting, thank you for explaining that!

At Dinorwig they have a surge shaft and pond for the machine shutting down quickly. Ffestiniog has relief valves which open quickly when the machines trip

All of it? I'm sure the designers accounted for that potential occurrence.

Pretty sure they have two independent oil cylinders and pumps. But how to close manually if one of them fails? Maybe by letting the oil out manually..

@@AndreasDelleske No you just need a bypass valve, the weight will push the fluid around.

Not an issue. Even if one of the hydraulic lines did rupture the drop in fluid pressure would not be that drastic. It would not slam shut like you think.

This is dinosaur technology people. Duh. How long do you think we’ve used hydraulics in every application possible and dams??

lmao!!

One hell of a water hammer I bet

Those bolts will be severely tested if the main valve trips on full flow, the counterweights will slam it shut as soon as the hydraulic pressure is lost. The water hammer due to the flow of water suddenly stopping will cause a huge surge in pressure. There is probably a surge relief somewhere on the pipework behind that wall.

@@letrainavapeur Even if you just chop the hydraulic line in half, the fluid doesn't vanish. The weights will still be working against the remaining hydraulic fluid as it's pushed out of the leak. It won't close slowly, but it won't be instant either, it'll still have some resistance to work against.

@@nate0031 Now imagine the hydraulic shaft mount breaking, causing the entire cylinder to drop along with the counterweight. It may be unlikely, but still a possible failure mode to be considered and calculated.

@@johndododoe1411 I'm sure they have a heck of a safety margin built in. They also likely have surge tanks or such for a worst case scenario.

Run the unit just off grid frequency, wait till your angles are close enough, and close it in.

Windmill can be started quickly too? I guess solar is always on. And all the others work with a steam turbine, I don't know if they keep the pressure up even when it's not generating, but it sure add some inertia to the system.

@@ameunier41 Gas takes about half an hour to start up

mega battery farms are the fastest to respond. less than 50 milliseconds with tesla megapacks. proven in australia. unparalleled frequency keeping.

The wicket gates on a hydro plant are between 5-20 seconds which let water into turbine. The MIV is upstream and usually takes 1:30 to 3 minutes to reduce open closing water impulse. It’s an additional water tight seal to close water off to turbine.

@@ronblack7870 private message me. I have an incredible graph which compares Tesla storage vs pump storage in Australia. Pump Storage has incredible numbers.

For emergency close

@@CarlosSilva-gc8ny wont that give a water hammer effect ? If it slams close

@@ljmike1204 I doubt it would slam, but the weight adds the ability to let it close without power, if the hydraulics ever fail for instance. It probably wouldn't fall like a stone. In case of failure I would imagine they can disconnect the lines from the rams, and use them as dampers, squirting hydraulic oil, hopefully into a bucket, and allowing the valve to close in a more controlled manner. The bypass also adds some protection against over pressure as the valve closes, by allowing a path for the highest pressure peaks to dissipate. There are also likely fail safes in the form of other spring valves to prevent, and equalise, vacuums and overpressures throughout the system.

@@ljmike1204 not if you dampen the return stroke of the cilinder

@@ljmike1204 Yes, the water hammer effect is enormous on hydropower plants. That's why surge tanks are necessary