Understanding the conversion between horsepower (HP) and kilowatts (kW) is crucial for engineers. This guide explains formulas, common values, and practical applications of HP to kW conversions.

Common HP to kW Conversion Table

Source: Blackcircles.com

Conversion Formulas and Detailed Explanation

1. Mechanical Horsepower (Imperial)

• Formula: kW = HP × 0.7457
• Explanation: One mechanical horsepower is defined as 745.7 watts. Since 1 kilowatt equals 1,000 watts, the conversion factor is 0.7457

2. Electrical Horsepower

• Formula: kW = HP × 0.746
• Explanation: One electrical horsepower is defined as 746 watts. This unit is commonly used for electric motors and air conditioning systems.

3. Metric Horsepower

• Formula: kW = HP × 0.7355
• Explanation: One metric horsepower is defined as 735.5 watts. This unit is widely used in Europe, particularly in the automotive industry.

4. Boiler Horsepower

• Formula: kW = HP × 9.8095
• Explanation: One boiler horsepower is defined as 9.8095 kilowatts. This unit is used to measure the energy output of steam boilers.

Real-World Applications

1. Industrial Pump Selection

In an industrial setting, selecting the appropriate pump requires converting the motor’s horsepower to kilowatts to ensure compatibility with the power supply.

• Scenario: A factory requires a pump with a 50 HP motor.
• Conversion: Using the mechanical horsepower formula: kW = 50 × 0.7457 = 37.285 kW
• Conclusion: The pump requires a power supply capable of delivering 37.285 kW.

2. Electric Motor Specification

When specifying an electric motor for a conveyor system, it’s crucial to convert the required horsepower to kilowatts to match the motor’s capacity.

• Scenario: The system requires a 75 HP motor.
• Conversion: Using the electrical horsepower formula: kW = 75 × 0.746 = 55.95 kW
• Conclusion: An electric motor with a capacity of at least 55.95 kW is necessary.

Extended Conversion Table

Source: UnitConverters.net

Detailed Conversion Formulas

1. Mechanical Horsepower (HP)

• Formula:
  kW = HP × 0.7457
  • Explanation: This formula applies when using mechanical horsepower, commonly used in North America.

2. Electrical Horsepower (hp(E))

• Formula:
  kW = HP × 0.746
  • Explanation: This unit is primarily used for electric motors and air conditioning systems.

3. Metric Horsepower (hp(M))

• Formula:
  kW = HP × 0.7355
  • Explanation: Widely used in Europe and Latin America, especially in automotive applications.

4. Boiler Horsepower (hp(S))

• Formula:
  kW = HP × 9.8095
  • Explanation: Used to measure the energy output of steam boilers.

Real-World Applications

Case 1: Industrial Pump Motor Selection

• Scenario:
  A manufacturing plant requires a pump powered by a 50 HP motor.
• Conversion:
  Using the electrical horsepower formula:
  kW = 50 × 0.746 = 37.3 kW
• Conclusion:
  A motor rated at at least 37.3 kW is required for efficient operation.

Case 2: Generator Sizing for Power Supply

• Scenario:
  A generator must supply 100 kW to an industrial facility.
• Conversion:
  Using the inverse electrical HP formula:
  HP = 100 / 0.746 ≈ 134.1 HP
• Conclusion:
  A generator with a minimum rated capacity of 134.1 HP ensures adequate power delivery.

Extended HP to kW Conversion Table

Additional Considerations

• Choosing the Correct Unit:
  Ensure the correct HP unit (mechanical, electrical, metric, or boiler) is selected for precise conversion.
• Power Supply Compatibility:
  Confirm that the converted kW value matches the available electrical supply to prevent overload or underperformance.
• Efficiency Factors:
  Consider equipment efficiency; actual power consumption may differ from rated power due to losses in the system.

Authoritative External Resources

• RapidTables: HP to kW Conversion
• InchCalculator: HP to kW
• UnitConverters.net: HP to kW
• Wikipedia: Horsepower