VFD or variable displacement? 1

[BrianE22]

I'm looking to purchase a hydrualic power supply, approx 25 HP. Just wondering, won't a fixed displacement pump and VFD accomplish the same thing as a variable displacement pump?

 

[micalbrch]

I dare to bet that a VFD in combination with a hydraulic gear or vane pump will not work for BrianE22's application because of the speed and stroke time of his actuator. Keep in mind how quick the pressure rises when the actuator reaches its end position. We are talking about milliseconds. That's at least how I understood his actuator. Of course you can work with proximity switches or stroke sensors which give feedback to the VFD before the actuator reaches its end position, but how far shall he goes with a control loop if a simple pressure/flow compensated piston pump works without complicated control loop.

 

[hydtools]

BrianE22, how fast a response time do you need?
See Vickers reference for pressure-compensated piston pump:

http://www.vickershydraulics.ru/pages/hydraulics/pumps/pdf/512702en0999a.pdf

How effecient do you need? Pressure-compensated piston pump is 90+%.

Rapid response, high efficiency words don't mean much.

Ted