Motor kW to Resistance Calculator

Calculate equivalent motor resistance for AC systems

Motor kW to Resistance Calculator

Compliant with IEC 60034 Standards

Results:

Equivalent Resistance (Ω): 0.00

Motor kW to FLA Calculator
Motor Locked Rotor Current Calculator

How to Use the Calculator

Single Phase Motor

  1. Enter Motor Power in kW
  2. Provide Voltage in Volts
  3. Input Power Factor (0-1)
  4. Enter Efficiency in percentage (0-100)
  5. Select "Single Phase"

Three Phase Motor

  1. Enter Motor Power in kW
  2. Provide Line-to-Line Voltage in Volts
  3. Input Power Factor (0-1)
  4. Enter Efficiency in percentage (0-100)
  5. Select "Three Phase"

Understanding Resistance

  1. The calculated resistance is an equivalent value.
  2. It represents the total effective resistance of the motor's electrical input.
  3. This value is useful for understanding power dissipation and circuit analysis.

Motor Electrical Fundamentals

Motor Power & Efficiency

Motor power (kW) is the mechanical output. To find the electrical input power, we must account for the motor's efficiency. Efficiency is the ratio of output power to input power.

Power Factor & Resistance

  • Power Factor (PF) indicates how effectively electrical power is converted into useful work.
  • Equivalent Resistance (Ω) represents the total opposition to current flow in the motor's electrical circuit, considering both real and reactive power components.

Key Formulas:

Input Power (W) = (Motor Power (kW) × 1000) / Efficiency (%)

Single Phase Resistance (Ω) = (V² × PF × Efficiency) / (kW × 1000)

Three Phase Resistance (Ω) = (√3 × V² × PF × Efficiency) / (kW × 1000)

Calculation Formulas

Input Power (W):
P_input = (P_motor_kW × 1000) / (Efficiency / 100)

Single Phase Resistance:
R = (V² × PF × (Efficiency / 100)) / (P_motor_kW × 1000)

Three Phase Resistance:
R = (√3 × V² × PF × (Efficiency / 100)) / (P_motor_kW × 1000)

Example Calculation

Three Phase AC Motor:

Motor Power: 10 kW

Voltage: 400 V

PF: 0.85

Efficiency: 90%

Efficiency (decimal) = 90 / 100 = 0.9

Input Power (W) = (10 × 1000) / 0.9 = 11111.11 W

Resistance (Ω) = (√3 × 400² × 0.85 × 0.9) / (10 × 1000) = 21.22 Ω

Equivalent Resistance = 21.22 Ω

Related Power Calculators

Motor No-Load Current Calculator

Calculate the no-load current of an AC motor.

Try Calculator

Motor Nameplate Calculator

Interpret and calculate values from a motor nameplate.

Try Calculator

Motor Overload Setting Calculator

Determine the correct overload setting for motor protection.

Try Calculator