Voltage drop

Status
Not open for further replies.
I'm a bit hung up on a question , I need some guidance as to where & how I can solve it.

The voltage drop percentage for a panel feeder with a non-continuous load of 180A, using 3/0 THWN copper conductors at 480V, 3Ø, & a length of 248' is____

A.) 1.23%
B.) 1.28%
C.) 1.42%
D.) 2.03
 

ggunn

PE (Electrical), NABCEP certified
Location
Austin, TX, USA
Occupation
Electrical Engineer - Photovoltaic Systems
I'm a bit hung up on a question , I need some guidance as to where & how I can solve it.

The voltage drop percentage for a panel feeder with a non-continuous load of 180A, using 3/0 THWN copper conductors at 480V, 3Ø, & a length of 248' is____

A.) 1.23%
B.) 1.28%
C.) 1.42%
D.) 2.03

Single phase or three phase?
 

Carultch

Senior Member
Location
Massachusetts
I'm a bit hung up on a question , I need some guidance as to where & how I can solve it.

The voltage drop percentage for a panel feeder with a non-continuous load of 180A, using 3/0 THWN copper conductors at 480V, 3Ø, & a length of 248' is____

A.) 1.23%
B.) 1.28%
C.) 1.42%
D.) 2.03

Calculate the "effective round trip resistance" for the three phase line, by using R=L*r*sqrt(3)/1000. From there, it is simply the Ohm's law equation, with the phase-to-phase voltage and the per phase current. Then divide by the phase-to-phase voltage, and multiply by 100, to express it as a percent.

L is the one-way length
r is the ohms/1000 ft for the wire size & metal.
 

don_resqcapt19

Moderator
Staff member
Location
Illinois
Occupation
retired electrician
If you really want to get down to the difference between 1.23 and 1.28%, you will need a lot more information....power factor, raceway or cable type, and ambient temperature.

That being said, I expect that they have given you a formula that they expect you to use to get this answer. If you use that formula and the correct information, you will get the answer they want.
 
Location
Marysville ohio
Occupation
Journeyman Electrician
If you really want to get down to the difference between 1.23 and 1.28%, you will need a lot more information....power factor, raceway or cable type, and ambient temperature.

That being said, I expect that they have given you a formula that they expect you to use to get this answer. If you use that formula and the correct information, you will get the answer they want


THE ANSWER TO YOU QUESTION IS 1.23%.
 
Status
Not open for further replies.
Top