Wildsoldier PE
Well-known member
- Joined
- Aug 19, 2010
- Messages
- 290
- Reaction score
- 14
I dont agree with this answer. But I could be wrong GA Tech review course discuss a problem similar like this but with different values the pages from the GA Tech review notes are NEC 21-23.
Zeff=.07(400f/1000ft) = .028
Vphase = 277.12V
Vdrop in the line from line to neutral = 70A x .028ohms = 1.96V <--- this is a line to neutral voltage drop
Vdrop line to line = 1.96V x square(3) = 3.39V line to line
V@ load = 480Vline to line - 3.39Vline to line=476.61 (choose 476V) Answer B
Book shows 478Volts as a correct answer.
I think the book forgot to convert the Line to N Vdrop to line to line Vdrop.
Zeff=.07(400f/1000ft) = .028
Vphase = 277.12V
Vdrop in the line from line to neutral = 70A x .028ohms = 1.96V <--- this is a line to neutral voltage drop
Vdrop line to line = 1.96V x square(3) = 3.39V line to line
V@ load = 480Vline to line - 3.39Vline to line=476.61 (choose 476V) Answer B
Book shows 478Volts as a correct answer.
I think the book forgot to convert the Line to N Vdrop to line to line Vdrop.