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Re: Quick questions about PFC calculations
Original poster: "Barton B. Anderson" <bartb@xxxxxxxxxxxxxxxx>
Hi Mike,
PFC equations are ballpark values. Once you ballpark a PFC value,
then test around that range to find the least current draw. You
worked out the value just fine. And yes, connect the PFC directly
across the LV input terminals.
There are more direct routes to get to the value. For reference, here is one:
PFC(uF) = (VA*10^6)/(2*pi*F*Vin^2) =
(9000*.03*10^6)/(6.28*60*120*120) = 49.74uF
A resistive load is likely referred to for helping with inductive
inrush currents or other inductive changes in current. The PFC won't
help with that. You may need a ramp up or some type of soft start
scheme to make the inverter happy.
Take care,
Bart
Tesla list wrote:
Original poster: Mike <megavolts61@xxxxxxxxx>
Hi all,
I've never worried about power factor correction in a NST
powered coil, but I got this great lil 9/30 (Thanks again Hal) and
thought it might be cool to run it from my car via a 400W inverter
that I have.
I know the inverter would not like an inductive load. The
instruction said I should probably run a resistive load at the same
time if it acted up, but I would think power factor correction would
be the way to go.
My question is: Did I calculate this cap correctly? First I
get 270VA/120V = 2.25 A, then dividing 120 by 2.25 and get 53.333 ohms.
Now measure the resistance across the primary I got 2.2 ohm so I
assumed the impedance due to the inductance is 51.1 ohm...the
difference between the calculated and measured. Then using XL -
Xc = 1/(2*pi*60*51.1) I got 49.7 uF.
Am I on track here? I am assuming the cap would go parallel to
the input, but please correct me if I am mistaken here(thinking
anti rsonant LC circuit).
Thanks,
Mike
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