[bobelectric]

Headgate as in longwall?

 

[Nuzzie]

Headgate as in pennstock headgate.

 

[MTW]

Looks like it should have been a bit bigger.

 

[HARRY304E]

Looks like it should have been a bit bigger.

Agreed.

 

[Big John]

What's that supposed to do? Does it assures the accumulators dump or something?

 

[Nuzzie]

Looks like it should have been a bit bigger.

You're telling me. Nothing I could do about it though.

What's that supposed to do? Does it assures the accumulators dump or something?

Just ensures being able to trip the headgate solenoid from the capacitor charge if there's a loss of power. The way the engineer has designed it is that if the PLC loses power, it drops out the output to the contactor in the picture, which disconnects the DC supply and connects the solenoid across the capacitors.

 

[Big John]

...Just ensures being able to trip the headgate solenoid....

I guess that was my roundabout question is what does the solenoid do? I don't understand what a "trip" device on a headgate would do unless it's closing a hydraulic gate.

 

[ScooterMcGavin]

To me this seems like a hokey way of doing it. Seems like the solenoid should be fail safe and close the gate on loss of power, or it should trip using the plant DC.

 

[Big John]

To me this seems like a hokey way of doing it. Seems like the solenoid should be fail safe and close the gate on loss of power, or it should trip using the plant DC.

I don't know what the application is, but this could be a designed as "DC backup"? E.g., a lot of circuit breakers have capacitive trip as well as DC source, so you end up with double redundancy.

 

[JRaef]

I don't know what the application is, but this could be a designed as "DC backup"? E.g., a lot of circuit breakers have capacitive trip as well as DC source, so you end up with double redundancy.

I think that's exactly what it is. On a head gate going into a penstock (pipe feeding water into a hydro generator), you must have redundant systems that will maintain control of the gate at all times. So if the generator trips for some reason and you have to stop the water from spinning it, or the penstock bursts somewhere and you have to stop the flood or washout, but the DC power has failed, the back-up plan is this stored energy system dedicated to that one solenoid. It pulses the solenoid, which sets in motion a hydraulic operated gate valve that shuts off the water flow. It's a backup for the backup and it's a one-shot operation, but it can mean a lot in an emergency.

 

[Big John]

Just a weird design. Every system I've seen is a spring-opened valves held electrically closed. Makes it fail-safe instead of relying on DC.

 

[JRaef]

Just a weird design. Every system I've seen is a spring-opened valves held electrically closed. Makes it fail-safe instead of relying on DC.

We're talking BIG valves here.

 

[Going_Commando]

My penstocks are only 4'ers

 

[nrp3]

Its not the size of the penstock....

 

[Big John]

We're talking BIG valves here.

:laughing: That's where the confusion was coming from, I'm talking about the valves in the hydraulics that power the gate are spring loaded. So the power dies, the accumulator valves automatically dump, the pressure pushes the gate cylinders closed.