HP to Amps calculator is used to calculate the amperes from horsepower of the motor is known. You can use the Electrical calculator to find the current in single, 2, and 3 phase motor circuits as well as in dc circuits.
List of Contents
DC (Direct current) Calculations
In DC circuits amps is the ratio between the product of HP * 746 to Voltage times efficiency.
DC Amps = [HP * 746] / [E * %age Efficiency]
Example: Find the current passing through 24 volt, 1/2 HP motor having an efficiency of 95%.
Solution: Current = [0.5 * 746] / [24 volt * 0.95] = 16.35 Amps
Single phase AC Calculations
The single phase AC calculations involve the power factor in denomatior of equation.
Single phase Amps = [HP * 746] / [E * %age Efficiency * PF]
Example: Determine the amps in single phase 1 HP, 120-volt motor having an efficiency rating of 88% operating at a power factor 0.9.
Solution: Current = [1 * 746] / [120 * 0.88 * 0.9] = 7.84 Amps
Two Phase, 4 Wire AC Calculations
The two phase calculations are similar to 1 phase with an additional factor 2 in the denominators.
Two-phase Amps = [HP * 746] / [E * %age Efficiency * PF * 2]
Example: Determine the current flowing through a two-phase, 0.5 HP, 220 volt motor having an efficiency rating of 90% and a power factor of 0.92.
Solution: Current = [0.5 * 746] / [220 * 0.88 * 0.9 * 2] = 1.07 Amps
Three phase AC
The three-phase ac amps involve HP * 746 in the numerator and 1.73 times PF * Efficiency times voltages in the denominator. The formula is identical to the previous case with the difference of factor 1.73 instead of 2 in the denominator.
Three phase Amps = [HP * 746] / [E * %age Efficiency * PF * 1.73]
Example: Determine the current flowing through a three-phase, 2 HP, 400-volt motor having an efficiency rating of 93% and a power factor of 0.9.
Solution: Current = [2 * 746] / [400 * 0.93 * 0.9 * 1.732] = 2.57 Amps