LV vs MV VFD
LV vs MV VFD
(OP)
Hello All,
I am on a project that has a 200HP Chipper Discharge Screw Conveyor that needs to be controlled from a VFD. I have research that the cutoff from LV to MV VFD HP is 500HP. ie below 500HP LV VFD and above 500HP MV VFD due to the economics. Most of these papers were written in the 90s. Are they any recent studies that have this type of data?
I have searched this site and goolged that info and can not find recent studies. I am trying to build a case that we need to use a 460V VFD vs a 2300V VFD. The cost of the motor and drive in the LV case will be cheaper but the cabling and installation cost will be more. With the price of copper going up I suspect that the 500HP cut off is changing to a lower HP rating.
But is 200HP a candidate for 2300V VFD control?
TIA Jbuda54
I am on a project that has a 200HP Chipper Discharge Screw Conveyor that needs to be controlled from a VFD. I have research that the cutoff from LV to MV VFD HP is 500HP. ie below 500HP LV VFD and above 500HP MV VFD due to the economics. Most of these papers were written in the 90s. Are they any recent studies that have this type of data?
I have searched this site and goolged that info and can not find recent studies. I am trying to build a case that we need to use a 460V VFD vs a 2300V VFD. The cost of the motor and drive in the LV case will be cheaper but the cabling and installation cost will be more. With the price of copper going up I suspect that the 500HP cut off is changing to a lower HP rating.
But is 200HP a candidate for 2300V VFD control?
TIA Jbuda54





RE: LV vs MV VFD
The cost of a 2300V VFD is going to be extreme in comparison, partly because of the cost of the associated switchgear that goes with it, but also because at 2300V the VFD mfrs don't really make a 200HP drive. The smallest they make is probably 500HP, if even that small. They can LABEL it for 200HP, but you are really paying for whatever is the smallest power structure they can build. That used to be 2000HP at 4160V, so 1000HP at 2300V, but most likely it has come down since I last checked on anything that small.
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RE: LV vs MV VFD
You will pay a huge premium for a 2300 V drive compared to a 480 V drive for 200 hp.
RE: LV vs MV VFD
Keith Cress
kcress - http://www.flaminsystems.com
RE: LV vs MV VFD
"If I had eight hours to chop down a tree, I'd spend six sharpening my axe." -- Abraham Lincoln
For the best use of Eng-Tips, please click here -> FAQ731-376: Eng-Tips.com Forum Policies
RE: LV vs MV VFD
I have a general idea that >1MW should be looked at with MV systems and below that LV (400-690Vac)is generally accepted as being a more cost effective for new installations. There are exceptions but this is a general idea.
Retrofit applications would be looked at differently.
Unless you are looking at km's of power cable then looking at the economics of copper versus the cost of MV drives/motors/switchgear/support/spares etc would push it LV imho.
RE: LV vs MV VFD
Next week, I'm starting up a 1500hp 480V system on an extruder so even that can be justified under some conditions.
RE: LV vs MV VFD
In this case, 200hp is very small for 2300VAC unless you don't have the lower voltage available.
I have seen a 10kV soft-starter installed for a motor that was something like 17A before which was likely pretty comparable cost wise to what you are asking.