600HP motor

[bozzah]

Being new on distribution for medium voltage motors, I'll appreciate for some advice. I am working on a small job where 600hp motor is added to an existing system. What are factors to determine what is the preferred supply voltage? There is 600V and 4.16kV available. The idea is to use Variable Freq. Drive.
Any good web links regarding this topic would be great.

thanks.

 

[alehman]

600V will probably be less expensive.

 

[motorspert]

600V every time, significnt savings, harmonics may dictate a 12 pulse drive, maybe 4160V and a step down transformer.

 

[itsmoked]

4160V VFDs are in a different league from 600V VFDs.

That would probably blow away any possible motor price savings.

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com

 

[jahrtrix]

bozzah,

the 600 volt motor will let you have more options. Your
VFD choices are more plentifull where the 4160v you have limited vendors and in replacing the higher voltage may
require a longer down time. The safety of the technicians
working on the higher voltage is more of an issue.

the 600 volt motor will of course require larger wiring
and conduit, but the overall benefits outweigh that.

 

[JensenDrive]

600hP implies roughly 600kVA xfmr and busbar capacity. Not insignificant. Do you have such spare capacity? If this replaces exiisting across the line motors, then it is worth noting that replacing the across the line motors with VFD will reduce your momentary fault current. If you have done any arc flash analysis and breaker coordination analysis, then you may have to rework that section of the analysis.

 

[bozzah]

thanks all.

Jensen:

I got your point; at the moment I do not have details for 600V. In addtion to VFD, line reactor may be introduced for the harmonics purposes; which will cause some voltage drop and introduce impedance hence smaller fault.