What does 4000 VA mean?
Hi all, What exactly does 4000 VA mean in an autoformer? In a generator? In an inverter? Thanks in advance.
Forum Discussion
road-runner wrote:pianotuna wrote:
In the case of my PD 40 amp converter PF is 0.7 so 40 amps x 14.4 volts / 0.7 = 823 watts.
Is that correct?
40 amps * 14.4 volts = 576 watts DC output
576 watts DC output / 0.8 converter efficiency = 720 watts AC input needed
720 watts / 0.7 PF = 1029 VA AC input needed
Wonder how many different answers you'll get? I'm certainly not beyond making errors.
actually pretty close to actual current draw from the line for this unit. I've measured it on mine with the kilowatt meter and at full output and came up with VA close to your calculation. IIRC it was slightly under 1000VA, but the PD delivers the 40A at nearer 13V or less and tapers as the voltage rises and in most cases won't be delivering 40A at 14V, by then it is down in the 10s of amps.
and in the rv world there are quite a few items with reactive loads that draw way more current than the power rating indicates. Microwave ovens, converters/chargers, are two big examples. AC and most induction motors typically has a PF around .9, then there are all the wall warts, and TV's. etc.
and most generators are really rated in VA not watts, even though they are advertized in watts, (honda's, yamaha's etc.) there are some generators that can handle pretty high reactive loads.
