Variable Flow Pump system with VFD

[Okpower]

Hi all:

I am involved as electrical engineer in the designing of pump system for loading refrigerated products (PROPANE, BUTANE) to ships. This system will have a wide range of flow quantity since will be many different ships with many different capacities and flow rate limits. I am proposing a system of three pumps, 900HP each (2 operating and 1 spare). Just 1 pump will be drived by a VFD.

What should I consider to make a good design?
Should I specify the motor and the VFD in 460 V or in 4.16KV?

Thanks in advance.

 

[itsmoked]

Hard to say with that info.

1.4MW.

460 will probably cost less and doesn't require specially trained installers. It is rather borderline.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[Okpower]

Thanks itsmoked:
Just to clarify, I am thinking in just 1 VFD..(1 pump will be driven by just 1 VFD)900 HP, 675KW.

The second one will be operated directly to line, and the third one will be just in spare.

 

[itsmoked]

What's being used there now for power?

Keith Cress
kcress -

http://www.flaminsystems.com

 

[ScottyUK]

A big LV VFD will be much cheaper than a small MV one. If this was not a VFD application I would say go with the MV solution. If you have other MV motors and the staff to look after them I would think the economics will favour the two fixed speed pumps being MV and the variable speed pump being LV.


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If we learn from our mistakes I'm getting a great education!

 

[itsmoked]

Except Scotty when the VFD motor takes a dump and the spare is MV. I think they all need to be the same.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[Okpower]

This is a new project, for a new plant. And actually, it is difficult propose a 460 V motor for that power, because, the motor shal be capable to start with direct voltage.I have read about some "new" arrangement to control flow with several breakers, a small control logic and just 1 VFD to control up to 3 of 4 motors.
I am not with the mechanical considerations and the isolating transformer that should be used.