In this post, you’ll learn the basic formula to calculate current in 3 phase circuits when either of the watts, kilowatts, or horsepower is known. Let’s first check the formulas:
Let’s solve some examples to better understand them.
List of Contents
Formula to calculate current in 3 phase circuit from watts
Find the current which will flow through the circuit which has a 1000 watt load at the power factor of 90%. The operating source is 3 phase at 400 V.
From: I = P / (E * PF * 1.73) = 1000 watt / (400 * 1.73 * 0.9) = 1.60 A
Formula to calculate current in 3 phase circuit from kilowatts
Here is formula is similar as we did it previously, just the factor 1000 is multiplied in this case.
When HP is known
Determine the amperage loads of a 2 HP, 3 phase motor at the power factor of 85% whose rated efficiency is 90%. The voltages are 230.
From: I = (HP * 746) / (E * PF * Efficiency * 1.73) = 0.483 A
So that was all about 3 phase current calculations.
You can learn the calculation for single phase here.