I am taking (been taking ) NPCCI (promtetric) 2c electrical plan review test. There are NO plans, thats right, NO PLANS. my question is this, are there any useful formulas out there that include how to find ampacities for a three phase, 4 wire wye start motor. Can anybody show me any formulas using 480v 0r 460 v and does the service factor shown in the question (1.15 have any bearing on your answer at all? Any help at all will be appreciated, anything at all. I am having a difficult time, I passed everything else first shot, I can't pass this one.
motors other than dwellings
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electricalperson
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the service factor means the motor can run at 115% of its rated capacity for example.
2005 Nec
2005 Nec
430.32 Explains the service factor and/or temperature rise.
Because this is used in overload device calculations I assume that is what they are asking you to size. Normally you would use the nameplate amp rating for this, since it is not given you would use the tables:
430.247 through 430.251
Im suppose you could use the 1 HP = 746 watts but for testing I would stick with the tables.
Garrett
2005 Nec
430.32 Explains the service factor and/or temperature rise.
Because this is used in overload device calculations I assume that is what they are asking you to size. Normally you would use the nameplate amp rating for this, since it is not given you would use the tables:
430.247 through 430.251
Im suppose you could use the 1 HP = 746 watts but for testing I would stick with the tables.
Garrett
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