Converter: Kilowatts to Amps

There exists a method to convert kilowatts (kW) to amps through the utilization of the power formula of Watt's Law. According to this formula, the current is equivalent to the power divided by the voltage.

To adapt this power formula for kilowatts, the initial step involves converting kilowatts to watts. This can be achieved by multiplying the power in kilowatts by 1,000, resulting in the total number of watts.

Afterward, the power formula is applied by dividing the power in watts by the voltage in volts, thereby determining the current in amps.

Formula for kW to Amps:

Hence, when dealing with DC and single-phase AC circuits, the formula for converting kilowatts to amps is provided as follows: [1]

I(A) = P(kW) × 1,000V(V)

In this formula, the electric current I is measured in amps and is equal to the power P in kilowatts divided by the voltage V in volts.

For illustrative purposes, consider a circuit with a power of 1 kW at 120 volts. The current can be calculated as follows:

I(A) = 1 kW × 1,000120 V

I(A) = 1,000 W120 V

I(A) = 8.33 A

Hence, generating 1 kW of power at 120 volts will result in a current draw of 8.33 amps.

Accounting for motor efficiency and power factor:

It is crucial to account for equipment efficiency when determining the number of amps consumed for a given output power, as many devices are not entirely efficient in power usage. The efficiency of the motor (η) is defined as the ratio of power output to power input.

To determine the input current required to achieve a certain motor output power, the following equation is utilized:

I(A) = P(kW) × 1,000V(V) × η

Consequently, the current I in amps is equal to the power P in kilowatts divided by the voltage V in volts, multiplied by the efficiency η.

In alternating current power, the magnitude of real and reactive power together is referred to as apparent power, while the power factor represents the ratio of real power to apparent power. [2]

To calculate the input current required, taking into account power factor and efficiency for a specific motor output power, the following equation is employed: [1]

I(A) = P(kW) × 1,000V(V) × η × PF

The existing electric current in amperes is equal to the power amount in kilowatts divided by the voltage measure in volts, multiplied by both the efficiency percentage and the power factor proportion. If necessary, you can try out our power factor calculator by following this link: [MY_REDIRECT_PREFIX]https://www.inchcalculator.com/power-factor-calculator/ to determine the power factor.

For instance, let's calculate the current required for a 5 kW motor operating at 75% efficiency and with a power factor of 0.8, with a voltage of 240 volts.

I(A) = 5 kW × 1,000 / 240 V × 0.75 × 0.8

I(A) = 5,000 W / 144 V

I(A) = 34.72 A

Thus, in this particular example, the 5 kW motor will consume a current of 34.72 amps.

Now, let's elucidate the process of determining the current for a three-phase AC circuit.

The formulas used to convert kilowatts into amps for a three-phase AC circuit differ slightly from those employed for a single-phase circuit. You can select one of the following formulas based on whether you have a line-to-line or line-to-neutral RMS voltage. (Ref: [MY_REDIRECT_PREFIX]https://www.google.com/books/edition/NFPA_s_Electrical_References/raUyIi7i-asC [1] [MY_REDIRECT_PREFIX]https://books.google.com/books?id=1kS8DwAAQBAJ [3])

Using Line-to-Line Voltage:

I(A) = P(kW) × 1,000 / V_LL(V) × η × PF × √3

This formula calculates the current consumption for a single pair of wires within the three-phase system. In order to determine the current for all three pairs of wires, you should multiply the result by three.

Using Line-to-Neutral Voltage:

I(A) = P(kW) × 1,000 / V_LN(V) × η × PF × 3

This formula calculates the current usage for all three wires within the three-phase system. To find the current for a single wire, you need to divide the result by three.

For instance, let's find the current usage of a 25 kW three-phase motor with an efficiency of 80% and a power factor of 1, operating at 240 volts (line-to-line).

I(A) = 25 kW × 1,000 / 240 V × 0.8 × 1 × √3

I(A) = 25,000 W / 332.55 V

I(A) = 75.18 A

If you need to convert watts into amps, you can utilize our watts to amps conversion calculator by visiting [MY_REDIRECT_PREFIX]https://www.inchcalculator.com/watts-to-amps-calculator/.

Here are the motor current ratings for both three-phase and single-phase AC systems:

Motor Current Ratings (Three-Phase AC)

Motor Current Ratings (Single-Phase AC)

These ratings are determined based on the kilowatt output levels at 120 and 240 volts for single-phase AC systems, with an efficiency of 0.8 and a power factor of 1.

Power

Current at 120V

Current at 240V

1 kW

Below are the modified values for the given electrical current values:

10.417 Amperes

5.208 Amperes

2 Kilowatts

20.833 Amperes

10.417 Amperes

3 Kilowatts

31.25 Amperes

15.625 Amperes

4 Kilowatts

41.667 Amperes

20.833 Amperes

5 Kilowatts

52.083 Amperes

26.042 Amperes

6 Kilowatts

62.5 Amperes

31.25 Amperes

7 Kilowatts

72.917 Amperes

36.458 Amperes

8 Kilowatts

83.333 Amperes

41.667 Amperes

9 Kilowatts

93.75 Amperes

46.875 Amperes

10 Kilowatts

104.17 Amperes

52.083 Amperes

15 Kilowatts

156.25 Amperes

78.125 Amperes

20 Kilowatts

208.33 Amperes

104.17 Amperes

25 Kilowatts

260.42 Amperes

130.21 Amperes

30 Kilowatts

312.5 Amperes

156.25 Amperes

35 Kilowatts

364.58 Amperes

182.29 Amperes

40 Kilowatts

416.67 Amperes

208.33 Amperes

45 Kilowatts

468.75 Amperes

234.38 Amperes

50 Kilowatts

520.83 Amperes

260.42 Amperes

55 Kilowatts

572.92 Amperes

286.46 Amperes

60 Kilowatts

625 Amperes

312.5 Amperes

65 Kilowatts

677.08 Amperes

338.54 Amperes

70 Kilowatts

729.17 Amperes

364.58 Amperes

75 Kilowatts

781.25 Amperes

390.63 Amperes

80 Kilowatts

833.33 Amperes

416.67 Amperes

85 Kilowatts

885.42 Amperes

442.71 Amperes

90 Kilowatts

937.5 Amperes

468.75 Amperes

95 Kilowatts

989.58 Amperes

494.79 Amperes

100 Kilowatts

1,041.7 Amperes

520.83 Amperes

125 Kilowatts

1,302.1 Amperes

651.04 Amperes

150 Kilowatts

1,562.5 Amperes

781.25 Amperes

175 Kilowatts

1,822.9 Amperes

911.46 Amperes

200 Kilowatts

2,083.3 Amperes

1,041.7 Amperes

225 Kilowatts

2,343.8 Amperes

1,171.9 Amperes

250 Kilowatts

2,604.2 Amps

1,302.1 Amps

275 kilowatts

2,864.6 Amps

1,432.3 Amps

300 kilowatts

3,125 Amps

1,562.5 Amps

325 kilowatts

3,385.4 Amps

1,692.7 Amps

350 kilowatts

3,645.8 Amps

1,822.9 Amps

375 kilowatts

3,906.3 Amps

1,953.1 Amps

400 kilowatts

4,166.7 Amps

2,083.3 Amps

425 kilowatts

4,427.1 Amps

2,213.5 Amps

450 kilowatts

4,687.5 Amps

2,343.8 Amps

475 kilowatts

4,947.9 Amps

2,474 Amps

500 kilowatts

5,208.3 Amps

2,604.2 Amps

525 kilowatts

5,468.8 Amps

2,734.4 Amps

550 kilowatts

5,729.2 Amps

2,864.6 Amps

575 kilowatts

5,989.6 Amps

2,994.8 Amps

600 kilowatts

6,250 Amps

3,125 Amps

625 kilowatts

6,510.4 Amps

3,255.2 Amps

650 kilowatts

6,770.8 Amps

3,385.4 Amps

675 kilowatts

7,031.3 Amps

3,515.6 Amps

700 kilowatts

7,291.7 Amps

3,645.8 Amps

725 kilowatts

7,552.1 Amps

3,776 Amps

750 kilowatts

7,812.5 Amps

3,906.3 Amps

775 kilowatts

8,072.9 Amps

4,036.5 Amps

800 kilowatts

8,333.3 Amps

4,166.7 Amps

825 kilowatts

8,593.8 Amps

4,296.9 Amps

850 kilowatts

8,854.2 Amps

4,427.1 Amps

875 kilowatts

9,114.6 Amps

4,557.3 Amps

900 kilowatts

9,375 Amps

4,687.5 Amps

925 kilowatts

9,635.4 Amps

4,817.7 Amps

950 kilowatts

9,895.8 Amps

4,947.9 Amps

975 kilowatts

10,156 Amps

5,078.1 Amps

1000 kilowatts

10,417 Amps

5,208.3 Amps