Finding the line current in an ac circuit

[james99]

Homework Statement

Given the load impedence is 18 + j15 ohms, what is the line current. Follow this link to see the circuit and the variables. http://www.flickr.com/photos/61312863@N07/5584165017/

Homework Equations

Vab = Van*root[3] angle 30 degrees
Iab = Vab/Z
Ia = Iab*root[3] angle -30 degrees

The Attempt at a Solution

Load impedance = 18 + j15 = 23.43 angle 39.8

Vab = root[3]*100 angle 30 degrees = 173.21 angle 30 degrees

Iab = 173.21<30/23.43<39.8 = 7.39<-9.8

Ia = 7.39<-9.8 * root [3]<30 = 12.80<-39.8

 

[member38644]

Therefore, the line current in the circuit is 12.80 amps, with a phase angle of -39.8 degrees. This means that the current is leading the voltage by 39.8 degrees.