I have a 5hp motor 240 volts wound rotor 150ft wire one way 12.9 ohms was given this was a ? they want to know the wire size that will maintain a 5% vd dont want the answer want the steps to get it thanks. aslo where do you find info on a desgin b motor i see the locked rotor section but what about flc on it
motor vd
- Thread starter mj324
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rtbullfighter
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Single Phase (K is your constant)
VD =2 x L x K x I / CM (circular Mils)
Three Phase (K is your constant)
VD =1.732 x L x K x I / CM (circular Mils)
K= constant 12.9 for copper and 21.2 for aluminum
L= Length
I= Ampacity/FLC
Don't forget the 5% is from the "Source" which would be the Main Distribution Panel, not a sub panel. When I do it I try to stay within 3% VD from the panel it originates from.
As for the FLC on the design B, i will try to get back to you on that, I left the 2008 code book at work this weekend. srry. Although if it has a "name plate", the FLC on the name plate will override any FLC that the NEC will give (given that the torque rating on the motor may be not as great or greater).
VD =2 x L x K x I / CM (circular Mils)
Three Phase (K is your constant)
VD =1.732 x L x K x I / CM (circular Mils)
K= constant 12.9 for copper and 21.2 for aluminum
L= Length
I= Ampacity/FLC
Don't forget the 5% is from the "Source" which would be the Main Distribution Panel, not a sub panel. When I do it I try to stay within 3% VD from the panel it originates from.
As for the FLC on the design B, i will try to get back to you on that, I left the 2008 code book at work this weekend. srry. Although if it has a "name plate", the FLC on the name plate will override any FLC that the NEC will give (given that the torque rating on the motor may be not as great or greater).
RETRAINDAILY
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rtbullfighter
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Somebody please help if I am wrong, but from what I am seeing the "Design Letter" (like B) refers to what the motor is for, example: High torque, Low torque, Efficiancy, etc.
I did find however in the 2008 NEC on page 70-301 in code referance 430.7(A)(9)FPN that the "Motor design letter definitions are found in ANSI/NEMA MG 1-1993, Motors and Generators, Part 1, Definitions, and in IEEE 100-1996, Standard Dictionary of Electrical and Electronic Terms."
I did find however in the 2008 NEC on page 70-301 in code referance 430.7(A)(9)FPN that the "Motor design letter definitions are found in ANSI/NEMA MG 1-1993, Motors and Generators, Part 1, Definitions, and in IEEE 100-1996, Standard Dictionary of Electrical and Electronic Terms."
hurk27
Senior Member
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- Portage, Indiana NEC: 2008
Table 430.150 will give you the NEC answer to the FLC for the motor your describing. also look at Table 430.151(B) for loc-rotor values, oh and for a 240 volt motor use the 230 volt standard.
Is this is a test question?
Is this is a test question?
- Occupation
- Licensed Electrician
If it's not a test question then please tell me where you got a wound rotor motor and what you are using it for.
hurk27
Senior Member
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- Portage, Indiana NEC: 2008
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- Licensed Electrician
I've only seen one. It was for a mine. Big motor! Big resistors! I was fascinated by the thing.
I want one to put in my yard as the center of a landscaping feature.
I want one to put in my yard as the center of a landscaping feature.
hurk27
Senior Member
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- Portage, Indiana NEC: 2008
Sorry wrong year:roll:
Table 430.251(B) for 2008 for LR
and Table 430.249 for 2008 for FLA
keep in mind the note at the top:
so for a 230 volt motor use 240 volt
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