Hydraulic APU

[itsmoked]

An auxiliary hydraulic unit for C130s presently needs to be powered with a generator every time they want to use it because it's a vintage 440 50/60Hz unit and the only outlet available is a 600V one.

They want to be able to normally plug into the outlet but to also fall back on the generator if required due to earthquakes, or remote parking, or whatever.

This means mounting up some heavy bank of transformers and two separate plugs and varied protection and operators having to not make setup mistakes.

Can a VFD(s) be used to provide soft-start and accept both voltages while subsequently putting out just 440V (~460V)?

I'm talking dual 60HP motors.

Any other thoughts welcome too.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[jraef]

Yes, Keith.
If you buy a 600V VFD, you can program it so that the maximum output voltage at full speed is always 440V, regardless of what the input voltage is (as long as it's >440V!). As you know though, you need to be a little careful running HPUs with SS motor controls such as VFDs because if the unloader / recirc valve sticks, you can damage the controls on startup in short order.

 

[MikeHalloran]

It might be lighter and easier to just add a smaller parallel hydraulic unit powered by local electric power, or a chainsaw engine.

I.e., do they really need 120HP of hydraulics for ground operations, or could they be a little patient?



Mike Halloran
Pembroke Pines, FL, USA

 

[itsmoked]

Thanks Jeff that's what I thought. I'll keep your admonitions in mind.

That is a heck of a lot of energy. I agree, what could possibly demand so much, from a helicopter or plane sitting on the tarmac? Perhaps they run hydraulic motors for A/C or generators? At any rate I may have little say in that matter.


Keith Cress
kcress -

http://www.flaminsystems.com

 

[jraef]

I took a tour of a C130 up in Seattle once and IIRC, I think if you even want to tow the thing it needs hydraulic power for the landing gear / wheel systems because it raises the frame off of them. In other words without hydraulic power the plane can't even be moved with a tractor and some fields require that everything on the tarmac must be capable of being moved or moving.

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