My old 10 HP phase converter could barely survive my 200 amp welding machine, and the third leg sagged a lot and it vibrated etc.
So, today my wife and son left me alone for a whole day, and I made a new phase converter out of the old one.
The new phase converter lives in the enclosure from an old Ferrups UPS that I demolished a year ago. I put it on 4" casters for ease of moving.
It actually has two idler motors. One is a 10 HP idler, and another is a 7.5 HP idler. The first motor to start is the 10 HP.
If I decide that I need more power, I press a momentary push button switch after the first motor spins up, and that makes the second motor come up. It stays up until the system is switched off.
WITHOUT the second motor, my phase converter is a simple phase converter with starting capacitors between legs 1-3 (3 being the generated leg).
When the second motor is switched on, it also switches on extra capacitors between legs 2 and 3. Thus these capacitors (two between legs 1-3 and two between 2-3) instantly become balancing capacitors.
Effect of this on noise and vibration is very nice.
So, now basically I have a mercedes of phase converters. Some things need to be finished, such as properly placing that pushbutton, adding a distribution system for 3 phase, etc.
I used one Allen Bradley starter for the 10 HP motor, and a simple contactor for the second one. The A-B starter has W63 heaters.
I sawed off the shaft of the 7.5 HP motor with a Harbor freight bandsaw, and was impressed with its performance. (it did not fit the enclosure well).
No pictures yet, as my wife took our camera.
The new one takes about as much space as the old one, but it is taller, it has two levels. On the bottom level, the 10 HP motor lives, and on the upper level, everything else lives -- the 7.5 HP motor and electrics. The 7.5 HP and electrical shit are separated by a wall.
There is a fan on the bottom section and I need to add another fan for the top section.
It looks actually not so bad in the ferrups enclosure, like if it cost me $2000 or some such amount. The ferrups enclosure has better appearance than particle board.
Another helpful thing was putting carpet underneath the motors, thanks to Gunner's earlier suggestion. It helps tremendously. The new RPC only makes a nice humming sound, helping me know it is running.
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