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Fra avatar image
Fra asked

Difference VA and W on inverter

Please help me to understand the difference between VA and W on victron inverter!

For example I have a new Phoenix 500VA inverter.


The data sheet says: 500Va- 400w at 25C with non linear load with crest factor 3:1.

What means?


I understood that the relationship between w and va depends on the power factor.


but I didn't understand if it concerns the Power factor of the AC load or the Power factor of the inverter itself.


How much is the power factor of the victron inverters (low frequency inverters)?


Then 2 more questions:

1) why with purely resistive loads my inverter has an efficiency below 80% between input and output, while with inductive loads (chargers and motors) I see an efficiency of 96/98%?

2) why does it show "w" in the "instant view" of victron Connect, while if I enter the inverter it shows "VA"? And is the value always the same?



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Thank you.

Phoenix Inverter
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img-20230416-105017.jpg (113.1 KiB)
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1 Answer
Paul B avatar image
Paul B answered ·

this is the appliance that's being used that's causing the difference most reactive loads have a uncorrected power factor of around 80% or .8,

so Best you read up on how power fact works.

resistive loads don't have a power factor issue so they are 1:1 or 98% after internal losses 1:1 is 100%

reactive loads ie a electric motor have power factor issues some more or less than others. this is where the amps lead or lag the voltage, a 1:1 power factor is when voltage and current follow the same frequency sign wave, the figures you point out are just that a VA figure or a Watt figure.


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Fra avatar image Fra commented ·

Yes, thank you.

But why in instant view say"w", and entering in the inverter say "va"?

The value is ever the identical between w and VA. With resistive and reactive loads.


And why with reactive loads I see that power on the shunt is almost equal to output power of the inverter (96/98%)?


And with resistive loads I see more power on the shunt and less power on inverter output (78-84%)?


Then, with zero load (without any load), the inverter ever say 7-8 Va...

It is normal?



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