Motor drive

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tim89s

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Brush Prairie WA
I am trying to size ocpd and conductors for a drive (Volkmann is the maker). The nameplate states 90 amps 460 volt 3 phase. I have not seen the nameplate, the info was just e-mailed to me. So I don't know if the amp rating is FLC, but lets just assume it is. The customer states the only motor that drive will be connected to is 15 hp. Would I still have to go off the nameplate, or could I could I size according to the motor load. Thank you, Tim
 
I would size the overcurrent protection based on connected load. But let me ask you, why is the drive so oversized? I guess the drive is existing or reused per client's request and theres just a 15hp load added. In any case, it'd be great if you give a bit more background on the project since it may shed some light on other possible issues that doesnt come to mind otherwise.
 
my opinion, based on 430.122 is you would have to size it to the nameplate x 1.25.
 
skeshesh said:
I would size the overcurrent protection based on connected load. But let me ask you, why is the drive so oversized? I guess the drive is existing or reused per client's request and theres just a 15hp load added. In any case, it'd be great if you give a bit more background on the project since it may shed some light on other possible issues that doesnt come to mind otherwise.
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The company is moving from another state and bringing all existing equipment with them. This is the setup they currently have. Right now the drive is on a 50amp breaker. I was told that a majority of the wiring was done without inspections.
 
I dont think sizing based on load to be connected is "wrong" if they don't plan to add anything other than a 15HP and its a factory with trained people, but I'll retract my statement since what you guys are suggesting is probably the more proper engineering in case they do want to add other loads in the future.
 
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