Test Question Volt Drop

[MBLES]

Test Q. A 240v single phase feeder with 2.0 alum thwn supplying an existing panel 260' from DP. whats max load that can be placed on the panel so that the VD is limited to 3%?

I = 133100x 7.2/2x21.2x260 = 86.9 0r 87a

a 2/0 alu thwn is good for 135a and the max load for 3% VD is 87a on feeder panel does that sound right?

 

[gar]

180619-0851 EDT

MBLES:

For a 3% voltage drop at 240 V the drop is 7.2 V. The wire length is 2*260 or 520 feet. The I to produce this drop is I = 7.2/Z.

You can assume Z is DC resistance and use tables adjusted to your temperature conditions, and/or enter other factors.

Your result will be dependent upon assumptions, and other calculations to determine the scaling factor. You did not define where your scaling factor came from, and the assumptions behind the factor.

.

 

[MBLES]

180619-0851 EDT

MBLES:

For a 3% voltage drop at 240 V the drop is 7.2 V. The wire length is 2*260 or 520 feet. The I to produce this drop is I = 7.2/Z.

You can assume Z is DC resistance and use tables adjusted to your temperature conditions, and/or enter other factors.

Your result will be dependent upon assumptions, and other calculations to determine the scaling factor. You did not define where your scaling factor came from, and the assumptions behind the factor.

.

the question is a test question i got from a masters exam test review page. Its basically asking how much load i can put on the feeder panel without going over 3% VD. Its not a real application only a test question to get user how to use the VD formula based on whats know or unknown.

 

[david luchini]

does that sound right?

Yes