Digital or Rotary Phase Converters?

The little I know as I get into this hobby is so far the digital converter I bought and paid an electrician to install was unsuccessful. The American rotary phase converter I bought was an easy success. I put the motor outside in a custom built dog house sized enclosure and there is zero sound.
 
I have a 3 phase 12" Logan lathe, a single phase bench mill, and am rebuilding a 3 phase bridgeport clone. I chose to go with a rotary converter because it will expand to other equipment. As I was told, the newer equipment with more electronic controls needs the cleaner power of a rotary verses a static converter, and not a VFD at all. Older equipment can use a static easier but I think you loose something like 20-30% of its power.
 
I think one needs to make a distinction between terminology and products. A digital phase converter can be many things, the ones sold on Amazon are no more than a static converter with maybe some digital controls, and it is a POS based on many reviews. RPC's have been used for many years, but not what I would call clean power for the third leg. Phase Perfect (PP) is clean power per their numbers and reviews, and the provided the cleanist power other then line 3 phase power, and there is tight regulation of the generated leg. Both an RPC and the PP pass through the L1 an L2 line voltages and only generate the third leg. On a RPC the third leg voltage can vary significantly. PP can be used on multiple machines within the power rating of the unit used, and can supply something like 10X is rated power for short periods for motor starting.

VFD is a different setup, it generates all three legs of power, but it does so in such a way (PWM) that it cannot run electronics/controls and is made to directly to the motor, as the coils smooth the wave form. Reliability, they all have long times before failure with little to o maintenance. VFD's these days have MTBF on the order of 20-30 years, this would also apply to the Phase Perfect. RPC is pretty simple, the better factory ones should also last a ling time. With the reduced price of the Phase Perfect, it would be my first choice, and also with older motors it would be the best option if one requires clean 3 phase power. VFD would be next due to compact size and relatively easy install, then RPC followed by a static converter.
 
Dhal22 said:
The little I know as I get into this hobby is so far the digital converter I bought and paid an electrician to install was unsuccessful. The American rotary phase converter I bought was an easy success. I put the motor outside in a custom built dog house sized enclosure and there is zero sound.
Click to expand...
What brand digital converter did you buy?
 
I run vfds, used to run a RPC, and now run a Phase Perfect. For a single Bridgeport I'd use a vfd. If you acquire more machines, you may find that whole shop three phase is a good thing but you can decide then. I would not buy a 5 hp RPC. If any machine comes along with more than 3 hp you will be needing a larger unit so I'd want a minimum of a RPC that can start a 7.5-10 hp machine. Big enough to handle most shop equipment but not so large as to become unbalanced with a1 hp motor. My machines vary from 1-30 hp and a Phase Perfect is really necessary to deliver a balanced load across that wide range of amperage. Once you get into the 10 hp range, the PP is really a game changer. Even my old motors like it. Dave
 
mksj said:
I think one needs to make a distinction between terminology and products. A digital phase converter can be many things, the ones sold on Amazon are no more than a static converter with maybe some digital controls, and it is a POS based on many reviews. RPC's have been used for many years, but not what I would call clean power for the third leg. Phase Perfect (PP) is clean power per their numbers and reviews, and the provided the cleanist power other then line 3 phase power, and there is tight regulation of the generated leg. Both an RPC and the PP pass through the L1 an L2 line voltages and only generate the third leg. On a RPC the third leg voltage can vary significantly. PP can be used on multiple machines within the power rating of the unit used, and can supply something like 10X is rated power for short periods for motor starting.

VFD is a different setup, it generates all three legs of power, but it does so in such a way (PWM) that it cannot run electronics/controls and is made to directly to the motor, as the coils smooth the wave form. Reliability, they all have long times before failure with little to o maintenance. VFD's these days have MTBF on the order of 20-30 years, this would also apply to the Phase Perfect. RPC is pretty simple, the better factory ones should also last a ling time. With the reduced price of the Phase Perfect, it would be my first choice, and also with older motors it would be the best option if one requires clean 3 phase power. VFD would be next due to compact size and relatively easy install, then RPC followed by a static converter.
Click to expand...
Very well said Mark, agree 100%. I think a lot of the bad rap that VFD's get these days, are due to folks buying the cheapest unit they could find on ebay/amazon. All of the VFD's I have used personally, have been from Lenze, Hitachi, TECO, and have been flawless. You get what you pay for. Attention to detail on the install is important as well.
 
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