OT inverter duty motors, hydraulic app.

[TConnolly]

Motor: 60HP (44.8Kw), 480V, 60Hz, 1200RPM
Application: Axial piston hydraulic Pump, w/ electronic volume and pressure comp controls.

Motor will be on a VFD primarly for energy conservation reasons.

It will run approximately 15% of the time at 50% speed (30hz). During this time is will be virtually unloaded (pump frictional loads only). Depending on what we find out during comissioning of the system it will turn somewhere between 80% and 100% of speed for about 50-60% of the time - this will be for energy conservation because full HP is not required at these times.

Would you bother spec.-ing an inverter duty motor? Or will a standard motor be OK? I'm leaning toward the standard motor instead of inverter duty, but I thought I would solicit the opinion of the board because its collective "smarts" is quite formidable.

 

[CroCop]

How long are the motor leads? If they're of any distance, the dv/dt spikes will be significant enough to warrant an inverter duty motor IMO.

 

[TConnolly]

Leads will be no more than a few feet, 6-8 ft (2m). Inverter cabinet is on the HPU skid.

 

[CroCop]

That being said, I'm leaning towards the non inverter rated. How much $$$$ is the difference?

 

[Tom Jenkins]

1) The cost penalty for inverter duty motors nowadays is small to none.

2) If this is a variable volume pressure compensated pump, why are you using a VFD? Since you are already controlling the flow rate, and the system loads will determine the pressure, you will already be operating the system at variable power anyway. I don't think the VFD is going to save any energy. [hp = f(Q, P)]

 

[DickDV]

You want an inverter-duty motor (MG1 Part 31) but with TEFC enclosure. No need for any auxiliary cooling.

Actually, Tom Jenkins may well have a good point. Are you sure you are going to save any energy?

 

[CharlesM]

I don't understand why you need it with the pump controls. Unless its being used in the electronic part of the control. You want to make sure you use a good drive. This type of pump will start up with a high load. It takes a few cranks to get enough oil pressure for the pump to adjust and unload the motor.

If its a power thing then you could look at a soft start but drives are getting cheap it may be just as cheep to go with a drive.

I guess to answer your question I would go with inverter duty. If it cost to much you are buying from the wrong distributor.