On 23 Mar 2004 06:53:03 -0800, (gradstdnt) wrote:
I tried doing this just this past weekend when I balanced out my 7.5
hp idler. Adding the PF caps didn't decrease my line current, it
increased it.

I tried a multitude of run cap and then PF cap combinations while
balancing my converter to run my 5hp lathe. I found my best
combination for loaded balance was 120 mf between L1 and L3 and 80 mf
between L2 and L3. L3 being the manufactured leg. This yielded 243v
between L1 and L3 and 245v between L2 and L3. Incoming line voltage
is 244v. Likewise my currents for L1 are 8.1 amps, L2 7.8amps, and L3
7.7 amps. This to me is pretty close to generating real three phase
power. Unloaded L1 to L3 and L2 to L3 voltages are up around 270
volts.

That's not good. You're using too much tuning capacitance. You want the
unloaded voltage balance to be within 10%, and the loaded balance within
10%. You have the loaded balance within 1%, but the unloaded voltage is
too high. You could overstress circuitry connected to the wild leg when
operating lightly loaded. Let the voltage swing above and below nominal
by about the same amount when going from unloaded to loaded. Then
you'll find that a power correction cap will reduce the primary current.

Gary