Question

A balanced three-phase 208 V wye-connected source supplies a balanced three-phase wyeconnected load. If the line current IA is measured to be 20 A and is in phase with the line-to-line voltage VBC, find the per-phase impedance of the load

Answer 1

6.004 Ω

Step-by-step explanation:

For a Y- connected system given that :

Line voltage,
`$V_L = 208 \ V$`

Line current ,
`$I_L=20\ A$`

and specified that
`$V_L \ and \ I_L$` are in phase.

Hence the impedance will be pure resistive.

For Y-system

`$V_L = \sqrt3 V_(ph)$`

`$V_(ph)$` = phase voltage

`$V_(ph)$`
`$=(V_L)/(\sqrt3) = (208)/(\sqrt3)$`

= 120.08 V

Line current = Phase current

`$I_L = I_(ph) = 20 \ A$`

Now,
`$z_(ph) = (V_(ph))/(I_(ph))=(120.08)/(20)$`

= 6.004 Ω