Clarification for NCEES Question for Line to Line voltage when voltage across load is provided

Professional Engineer & PE Exam Forum

Help Support Professional Engineer & PE Exam Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

wfg42438

Active member
Joined
Feb 13, 2022
Messages
34
Reaction score
2
In the question below VAB across the load is given
We also know the line current across the conductor

In the solution the voltage across the load is divided by root three
why is this the case isnt the typical rule of thumb VL=Vphase for a delta configuration?

1647546827056.png
1647546859945.png
 
When you solve these kind of circuits, always draw the per phase equivalent circuit. The impedance of line are also per phase values. So, you calculate the phase values and change it to line values.

If the load is in delta, convert it into Y. For balanced load, Z_Y=Z_delta/3
 
Last edited:
When you solve these kind of circuits, always draw the per phase equivalent circuit. The impedance of line are also per phase values. So, you calculate the phase values and change it to line values.

If the load is in delta, convert it into Y. For balanced load, Z_Y=Z_delta/3

So in this question we assume we have converted Zdelta to Zy right?
But since we already know the Line to Line voltage across the load we simply say if converted to Y then the LN voltage is VLL<-30deg /sqrt (3)

is that right?
 
Back
Top