Calculate three-phase line current for delta or wye circuits from phase current, or from real/apparent power, line-to-line voltage, and power factor.

Balanced three-phase AC current magnitudes. Power inputs are total three-phase power; voltage is line-to-line RMS.

Line Current Formula (Balanced Delta Connection)

The following formula is used to calculate the line current for a balanced 3โ€‘phase delta (ฮ”) connection. 

IL = IP ร— SQRT(3)
  • Where IL is the line current (amps)
  • IP is the phase (branch) current in each delta leg (amps) 

For a balanced delta connection, calculate line current by multiplying the phase (branch) current by the square root of 3. For a balanced wye (Y) connection, the line current equals the phase current.

How to Calculate Line Current?

The following two example problems outline how to calculate the line current for a balanced delta (ฮ”) connection using the formula above.

Example Problem #1:

  1. First, determine the phase (branch) current in each delta leg (amps). In this example, the phase (branch) current is 56 A.
  2. Finally, calculate the line current using the formula above: 

IL = IP * SQRT(3)

Inserting the values from above and solving the equation with the input values gives: 

IL = 56 * SQRT(3) โ‰ˆ 96.99 amps

Example Problem #2: 

Using the same process as example problem 1, we first define the variables outlined by the formula. In this case, the values are:

phase (branch) current (amps) = 82

Entering these values into the formula above gives : 

IL = 82 * SQRT(3) โ‰ˆ 142.028 amps