sizing inverter 2

[rrzzan]

Guys,

How do you determine the size of an inverter.

For example, if I have 220kW dc power, then can I use 225kW inverter??

Thanks for your reply.

 

[burnt2x]

Watts is watts. A 4000kW inverter can power up 4000kW load! However, inverters have efficiencies as well as batteries. The 220kW DC power available you have posted, cannot be realized at the AC output. A total efficiency of 80% is reasonable for most inverter set-ups (divide Battery capacity by 1.25).
BTW, battery power is expressed in ampere-hours and not watts/kW.

 

[davidbeach]

burnt2x, interesting, but who said anything about batteries? Could be photovoltaic, and I've seen stated efficiencies in the low to mid 90% range. One cut sheet I have open states 93.0 and 93.5%, but does called it "weighted efficiency" what ever that might be. Best efficiency will happen closest to maximum rating.

 

[burnt2x]

David,
I agree with you. Batteries were not mentioned.
BTW, I still have to see photovoltaic systems without batteries for storing energy during sunny hours and discharging when the sun is out! I also said total efficiency as "reasonable" instead of "inverter plus battery".
You are right about your figures on inverter efficiency only, especially if your inverter is transformerless (as opposed to ferroresonant inverters).

 

[sibeen]

Surely this is putting the cart before the horse. An inverter is normally sized to provide a set load.

 

[Skogsgurra]

I am not even sure what the OP asks about.

It could also be so that he has a 220 kW DC motor and asks if that could be replaced by a 225 kW inverter plus induction motor.

I think that we need to know the real application before saying anything about this.

Gunnar Englund

http://www.gke.org

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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

 

[rrzzan]

I have been working with photovoltaic sytems so the power that I was talking about was not from any dc motor or such.

I got the answer. Thanks burnt2X, davidbeach and everybody for sharing.