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Why Motor rated in kW instead of kVA?

Why Motor rated in kW/Horsepower instead of kVA?

Why-Motor-rated-in-kW-instead-of-kVA

We already know that Transformer rating may be expressed in kVA instead of kW as well as Generator and Alternator rated in kVA. Designer doesn’t know the actual consumer power factor while manufacturing transformers and generators i.e. the P.F (Power factor) of Transformer and Generator/Alternator depends on the nature of connected load such as resistive, capacitive, and inductive load etc which affect the overall power factor of transformer and generators as the consume reactive power according to the load as well.

At the other hand, Motor has fixed Power factor, i.e. motor has defined power factor (p.f)  and the rating has been mentioned in kW on Motor nameplate data table. That’s why we are rated Motor in kW or HP (kilowatts/ Horsepower) instead of kVA. in more clear words, Motor only consume active power and provide mechanical power in HP or kW at motor shaft.

In addition, Motor is a device which converts Electrical power into Mechanical power. In this case, the load is not electrical, but mechanical (Motor’s Output) and we take into the account only active power which has to be converted into mechanical load. Moreover, the motor power factor does not depend on the load and it works on any P.F because of its design.

You may also read:
Why Transformer rating in kVa, not in kW?
Why AC (Air-condition)rating in Ton, not kW or kVA?
Why Alternator rated in kVA, not in kW?
Why Battery rating in Ah (Ampere hour) and not in VA.
Why Power Plant Capacity Rated in MW and not in MVA?

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19 Comments

    1. There is a AC synchronous generator with cosθ = 0.85 supply for a AC asynchronous motor with cosθ = 0.92
      Could you explain for me the different between two power factors.
      Thanks so much !

  1. There is a AC synchronous generator with cosθ = 0.85 supply for a AC asynchronous motor with cosθ = 0.92
    Could you explain for me the different between two power factors.
    Thanks so much !

  2. No . Motor power factor depends upon the load. Increasing the load increasing the power factor. So a induction motor should always be pit on maximum load. If we have only induction motor loads in a factory then we we use capacitor bank

  3. Its interesting while reading the informations. but answers are not clear in many topics. many of the answers are specified with some reasons. There wont be any explanation for those reasons. At the time, we get struck to believe the answers which are specified is really a correct. so please explain the reason along with the answer. then only the reader get to understand it clearly. just i expressed my suggestion. 🙂

  4. If we have three phase and neutral supply and we get deferent voltage between each phase and neutral. I want to know that how can we get equal voltage in between each phase and neutral.

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