![]() Motor Current Ratings (Single-Phase AC) Motor current ratings based on kilowatt output at 120 and 240 volts single-phase AC with an efficiency of 0.8 and a power-factor of 1. Motor current ratings based on kilowatt output at 120, 208, 240, 277, and 480 volts three-phase AC with an efficiency of 0.8 and a power-factor of 1. This formula measures the current draw for all three wires in the three-phase system to calculate the current for a single wire, you need to divide the result by three. This formula measures the current draw for one pair of wires in the three-phase system to calculate the current for all three pairs of wires, you need to multiply the result by three. amps 1000 × kilowatts / (3 × PF × volts). Use one of the formulas below for line to line or line to neutral RMS voltages. So amps are equal to 1000 times kilowatts divided by square root of 3 times power factor times volts. ![]() The formulas to convert kilowatts to amps for a three-phase AC circuit are a little different from the formula for a single-phase circuit. How to Find the Current of a Three-Phase AC Circuit In this example, the 5 kW motor will draw 34.72 amps of current. Try our power factor calculator to get the power factor if needed.įor example, let’s find the current of a 5 kW motor with an efficiency of 75% and power factor of 0.8 at 240 volts. The current I in amps is equal to the power P in kilowatts divided by the voltage V in volts times the efficiency η times the power factor PF. You might also be interested in our VA to kW calculator. Thus, the apparent power S in volt-amps is equal to 1,000 times the real power P in kilowatts, divided by the power factor PF. To find the input current required to achieve a certain motor output power accounting for power factor and efficiency, use the following equation. The formula to convert kilowatts to volt-amps is: S(VA) 1,000 × P (kW) PF. ![]() The magnitude of real and reactive together in alternating current power is called the apparent power, and the power factor is the ratio of real power to apparent power. Thus, the current I in amps is equal to the power P in kilowatts divided by the voltage V in volts times the efficiency η. To find the input current required to achieve a certain motor output power, use the following equation. Efficiency of the motor η, is defined as the ratio of power output to power input. How to Account for Motor Efficiency and Power FactorĮquipment is often not 100% efficient with power usage, and this must be factored in to find the number of amps consumed for a given output power. So, generating 1 kW of power at 120 volts will draw 8.33 amps of current. For example, find the current of a circuit with 1 kW of power at 120 volts.
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