250HP Motor Amp Ratings
250HP Motor Amp Ratings
(OP)
I'm having trouble finding the ampere ratings for a 250 HP 480V, 3-Phase motor.
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RE: 250HP Motor Amp Ratings
RE: 250HP Motor Amp Ratings
RE: 250HP Motor Amp Ratings
Cheap-and-dirty rule of thumb for 460V motors is 1.2 Amps/HP by the way. 250 x 1.2 = 300A, so pretty close to what dpc said.
JRaef.com
"Engineers like to solve problems. If there are no problems handily available, they will create their own problems." Scott Adams
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RE: 250HP Motor Amp Ratings
RE: 250HP Motor Amp Ratings
In general the NEC says that the motor currents shown in Tables 430.247, 430.248, 430.249, and 430.250 shall be used to determine the ampacity of conductors or ampere ratings of switches, branch-circuit short-circuit and ground-fault protection, instead of the actual current rating marked on the motor nameplate. 430.6(A)(1)
Don
RE: 250HP Motor Amp Ratings
Yes you're right of course. I was stuck thinking only of overload protection devices (I'm in the middle of a large project doing that right now).
JRaef.com
"Engineers like to solve problems. If there are no problems handily available, they will create their own problems." Scott Adams
For the best use of Eng-Tips, please click here -> FAQ731-376