Complex imaginary

[osh1397]

Isn't I1 the phase current and the line current should be :
1.732 * 143 = 247 A?

 

[Sam_]

They gave you a current of 62.7A on the secondary of T1. To get the primary current just transfer the current back the primary side of T1.

62.7 * ( 15000 / 6600) = 142.5 A

 

[osh1397]

They gave you a current of 62.7A on the secondary of T1. To get the primary current just transfer the current back the primary side of T1.

62.7 * ( 15000 / 6600) = 142.5 A

I was confused, this would give phase current, the primary is Delta. See below figure highlighted

The Primary current = I
The secondary current = a*I/1.732 = 62.7 A

Solve for I = 62.7 * 1.732/0.762 =142.5 A

 

[Sam_]

142.5 is your line current on primary just like 62.7 is your line on secondary side. I'm not sure what you're calculating.

Secondary = a*I/1.732 = 62.7 isn't necessary at they told you the current. you're not solving for the secondary current.

Taking the secondary current across to the primary side is just I_s / a = I_p