[Amps] three phase (try again)

[jeff millar]

If the HV supply uses choke input, then probably ok to use a VFD.  Cap
input filters have extreme current peaks at the peak of the line cycle.

I made my own 3 phase converter from a used 3 Phase motor.  Apply 240 to
two legs and it will generate the third voltage on the third leg.  Starting
requires a motor start cap momentarily from one input to the 3rd leg.  In
my case, I use it to power my small lathe. I just set the motor on the
floor and turn on the power, it hums excessively and would rapidly
overheat... but give the shaft a spin by swiping my foot across it and it
takes off.

Use a motor start contactor so if there is a power outage, the motor power
stays off when power comes back.  You would not want to leave a 3 phase
motor stalled on single phase for more than a few seconds.

jeff, wa1hco

On Thu, Dec 29, 2022 at 1:02 PM Paul Decker <kg7hf at comcast.net> wrote:

> Hello group,
>
> I've been exploring ways to get an AN/URT-23D running. It requires about
> 6KW, 60Hz 208V 3-phase power.
>
> I know I can use a rotary phase converter to create three phase from
> single phase.  There are 1 to 3 phase Variable Frequency Drives on Amazon
> for a couple hundred dollars, like the HKS VFD 7.5KW 10HP.
>
> There is a note in the hookup that says:  "Three phase output can only
> connect to pure resistance or pure inductance such as motors or electric
> heaters.
>
> My input is a Delta or Lambda transformer for control, bias, heater, and
> plate voltages.  Would one of these VFD's work to convert single phase to 3
> phase?  Barring any EMI switching issues they may have.
>
> Thanks,
> P
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