New to the site and new to phase converters. I have two CNC machines (1 runs at 7.5HP and the other at 20HP). If I only need to run one machine at a time what is the max converter I would need.... 20HP?
VFD exist that can be"ganged". I'd want to avoid that, 'coz they are not the cheap ones.
Current-generation Phase-Perfect MAY be "ganged". The diagram in right in the manual. You could use two 10 HP units, so long as both WERE same, and current, models.
Mine are not. One old style "blue case" 10 HP bought used, and of uncertain remaining life expectancy. One current-generation "white case" 10 HP with warranty. OTOH, my largest 3-P load is about 7 to 7.5 HP, so I have no need of ganging them.
Are two 10 HP less-costly than a single 20 HP? I don't think so. MORE expensive, rather.
But shop around. P-T has dealers. Some do a bit of discounting.
Also, I will connect the phase converter to my home. Does running the phase converter in my garage affect the power in my home?
Of course it does. If nothing else, a 20 HP load-motor sucks up a significant portion of the service entrance rated load AT LEAST for starting itself. Lights could dim briefly. But that isn't a disaster.
Service entrance rating is USUALLY optimistic as far as steady-state loads go. It is more of a peak rating that sustained- the last mile' Powerco transformer is USUALLY shared with two, three, even four residences, and normal probability of ALl of them trying to start a heavy load, same secodn is seriously low, even IF all of them are kitted-out with a "shop".
As to rude behaviour reflected back INTO the grid, or "upstream":
- A Phase-Perfect is about as good as it gets, BOTH feed and load side. Innocent as is practical to make it.
- A VFD is generally a very good citizen, utility mains side. Might be a tad rude, load side.
- A DC Drive can be a rude player to the grid and should have at least a Corcom-style RFI/EMI filter, preferably a "Drive Isolation" transformer, feed side.
- An RPC is Sine-Wave-Clean, load side, but generates artifacts up-grid from the way in which it works. Measure that upline rudeness as Total Harmonic Distortion. Unwelcome, but not really a show-stopper.