In a power electronics converter is there any difference between reactive power input to the converter and reactive power consume by converter? (In case source current waveform is square in nature). If yes then how we can calculate the difference between the two reactive powers?

  • $\begingroup$ It sounds like it's the same thing $\endgroup$
    – Jodes
    Commented Sep 23, 2016 at 5:29

1 Answer 1


Not sure if this is more of a comment or an answer but I hope it helps. Reactive power is never really consumed, so it's a misleading term. In inductive loads the reactive power goes into the magnetic field that is constantly switching directions. (like in electric motors for example). In capacitive loads the reactive power goes into the magnetic field between the two plates (like in capacitor banks).

I deal more with buildings and large equipment, rather than the electronic components, but an electrical utility company must size the feed into the building to accommodate the real power and the reactive power, which is by definition the apparent power (vector sum of real and reactive power). But the reactive power is constantly being fed back and forth because the magnetic fields are changing directions according to the frequency of the electricity provided.

So I believe they are the same thing. The reactive power input is the same as consumed.

With real power it's different because it's tangible. A resistive electric heater turns the electricity into heat so it's easier to conceptualize that it's 'consumed' but the power input is equal to the power consumed one way or another. But with real power you can't send it back. It's already been spent as heat.

Electrical utility companies will charge you based on your electricity consumption (units of kWh typically, which is a unit of energy) AND they will charge you based on your peak power draw because the more reactive load you have, the larger they have to size their equipment to accommodate BUT they don't charge you for consumption of reactive power because that does not occur.

I know it's a different application, but the general concept holds true and it really helped me to understand he difference.

  • $\begingroup$ Worked on a wind turbine where the active power output was reduced by 80% due to reactive power : needed to install a capacitor bank to deal with it, actually got it to around +/- 1%... $\endgroup$
    – Solar Mike
    Commented Apr 22, 2017 at 7:54
  • $\begingroup$ But should this be in Electrical? $\endgroup$
    – Solar Mike
    Commented Apr 22, 2017 at 7:55

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