Pump Estimated Inertias -HELP

[ThePunisher]

HI all,

I am currently intending to conduct a high level and very preliminary dynamic motor starting study just to have an insight on what the motor acceleration for a 2,000 HP and 900 HP motors would look like. The motors are initially perceived to be direct-on-line started and I just want to see if a reduced voltage starter would work to avoid placing a VFD just to start it.

Currently, we are at a very conceptual stage and this is just my engineering check. I was able to obtain some existing pumps in our files and was able to obtain the TORQUE vs. SPEED curves for pumps connected to 2,000 HP and 900 HP motors from our past records.

UNFORTUNATELY I DO NOT HAVE THE PUMP INERTIAS and I would like to seek some help here.

The pump connected to a 2000HP motor is a WEIR PUMP MODEL 14/12 AHPP rated for 1,491 kW at 900 RPM

The pump connected to a 900HP motor is a WEIR PUMP MODEL 14 AHFP rated for 518 kW at 400 RPM

I badly need the inertias and unfortunately, did not get anything from WEIR yet. Hope someone here can give me a ballpark or a way to estimate them.

Thanks

 

[BigInch]

You can estimate rotational moment of inertia, the the integral of dM x Radius of all rotating masses. For the pump it's the impeller and shaft, gears (if there is a gearbox), and motor shaft plus armature and windings. You're electrical, so I presume you know how to do that for the motor and can get it for the gears, if any. For the pump, assume the impeller is a disk and you just need the thickness and radius of the impeller and the mass density of that material. You also need the volume of fluid that is rotating with the impeller and the fluid's mass. Assume the volume of fluid is area, equal to the inside diameter of the discharge nozzle, x circumference of the impeller. I guess you know the mass density of the fluid.

 

[ThePunisher]

Got it thanks BgInch