question

kaarthik avatar image
kaarthik asked

load values shown in vrm not related with current

Dear all,

i want to know in remote console i saw the inverter load details and grid input details like voltage and current and power but its not related to each other , example please find the attached screen shot

ac in L1 voltage 241v and current 0.6A POWER =V*A SO 241V*0.6 A = 144W but in actual it shows 12W also in inverter output side 241V*2.3A=554W BUT It shows 383W can you please help me to understand why it is like that thanks in advance.


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1 Answer
wkirby avatar image
wkirby answered ·

You have to think about the power factor also.
True Power is measured in Watts and Apparent Power is measured in VA.
So, the "Watts" box is showing the true power and if you multiply the Volts and the Amps then you are calculating the Apparent Power in VA.
The relationship between VA and Watts is determined by the power factor of the circuit. This is the phase relationship between the Voltage and the current.
A purely resistive load like a heater would have a power factor of 1 or 100%, so your Watts and your VA would be the same. The Voltage and the current are in phase with one another.
A reactive load like a motor od switch mode power supply would have a power factor of less than 1. The Voltage and current are out of phase with one another. If the power factor is 0.5 or 50%, then Watts could show 100W, but the VA would be 200VA.

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kaarthik avatar image kaarthik commented ·

Dear sir ,

which means i need to pay for 12w or 144w , because if i measure using clamp meter as well as energy meter from Electricity board side both shows 0.6A as reading and units also changed as per calculated value.

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zain avatar image zain commented ·
Sir, is there a way to calculate that Power Factor from the csv file downloaded from the VRM portal?
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zain avatar image zain zain commented ·

The reason why i am asking this is, i have noticed in my system, the apparent power is sometimes less than the real power. Obviously if i divide both, the PF seems to be more than 1 which is impossible. So, what am i missing?

My system consists of 3 5kVA quattros, 3 phase supply.

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