Best VFD for screw pump

[DesertHeat]

Hi all,
we're working on a project that calls for variable flow at low pressure. 640 gpm @ 150 PSI max (2 units of 320 gpm each) and plan to use screw pump(s) driven by VFD powered motors.
been in the hydraulic business for some years now and think that i might as well use a hydrostatic drive to turn the screw pump.
The client though insists a VFD design so the question here is: did anybody worked with such a configuration? Any tips on what type of VFD should be used? Planning to use inverter-duty motors of TEFV design to make sure motor overheating doesn't come into the picture.
thanx

 

[StoneCold]

Desert Heat
We Use Allen Bradely drives. Just out of preference, I would just choose a major brand. The thing that I wanted to point out and that you may not realize is that most systems can only be slowed down to 20 hz (assuming your running 60hz). If your motors and bearings, and splash lubrication will tolerate it you might be able to hit 10hz but it is not common. Just something to keep in mind.

Regards
StoneCold

 

[micalbrch]

Ask the pump vendor whether the pump requires a constant torque VFD or a quadratic torque VFD. I think a screw pump needs a constant torque VFD but you'll better countercheck.