Noobie looking for phase converter advice

[Deerhurst]

I recently picked up my first piece of equipment to start my home shop and Im trying to figure out a phase converter. I am planning to add a lathe eventually.

I have a Bridgeport with a 2hp spindle and a 3hp hydraulic pump (synchro trace 2). It has an electronics cabinet and all the motors are controlled by the main panel so no VFDs. Im thinking I should be looking at a 7.5hp converter at minimum? Does this sound right?

Im thinking a rotary is best for my application (eventually want to wire it into the shop for each machine as I wont be able to run multiples at one time) vs a static. I know of a phase a matic that popped magic smoke with a small lathe on it (a question for later) and Im worried that the faux 3rd leg may cause issues with the contactors on my machine.

I see many recommendations for American Rotary here. I will be calling or emailing them soon to see what they say.

Any pointers, directions, etc would be much appreciated.

 

[Gordon Heaton]

7.5hp should be fine. I personally prefer American Rotary over Phasamatic, but my equipment is old (and dead-reliable) and it does not contain the circuitry that the newer models do.

 

[Deerhurst]

My machine is easily pre-1970s. Bunch of contactors the size of my head in the cabinet. As far as I can tell nothing fancy going on but I will dig into it more when I get it off the trailer.

I will shoot for 7.5hp or larger. I assume no issues with going too large?

 

[dalmatiangirl61]

I know of a phase a matic that popped magic smoke

Under the cover there is a bank of capacitors, thats it, nothing else. Caps are easy to replace, if the smoke came from windings its a boat anchor, you can ohm windings and check for shorts to ground. The voltage on the artificial leg runs high, supposedly with enough load it will drop into a more normal range, PAM sells a transformer to fix the problem. According to salesman at AR, their base model (AR Pro series) does the same, have not tried one to verify. So far its only been a problem with one of my machines, it trips the thermal overload switch. If you can get the dead PAM very cheap/free it could get you going. PAM and AR both use Baldor motors, until someone does a technical side by side comparison I say its a toss up on which is better. I have a PAM R20.

 

[hvnlymachining]

Going larger doesn't cause problems except adding to your power bill and initial cost. ( And giving you more excuses to buy bigger machines) it also allows using multiple machines at the same time. Just keep in mind total load on your shop feed lines.

I've run both static and rotary phase converters ( still do), you have to be careful with placement of the third "wild" leg always.

 

[mksj]

It is standard practice when using an RPC to not use the wild leg to power transformers and/or electronics, only use it to power the 3rd phase of the motor leg. The other two legs are pass through and would be either directly power the contactors or when using a transformer do not connect the wild leg to the transformer. Most RPC sites have recommendations as to RPC size for motor load, in general you need an RPC idler 2X the largest motor it will be used for.

 

[Deerhurst]

Under the cover there is a bank of capacitors, thats it, nothing else. Caps are easy to replace, if the smoke came from windings its a boat anchor, you can ohm windings and check for shorts to ground. The voltage on the artificial leg runs high, supposedly with enough load it will drop into a more normal range, PAM sells a transformer to fix the problem. According to salesman at AR, their base model (AR Pro series) does the same, have not tried one to verify. So far its only been a problem with one of my machines, it trips the thermal overload switch. If you can get the dead PAM very cheap/free it could get you going. PAM and AR both use Baldor motors, until someone does a technical side by side comparison I say its a toss up on which is better. I have a PAM R20.

When I got there to see why their lathe wasn't spinning I found they had the 220 in spread across one input pin and one output pin and the 3 phase out scattered too and had been trying to power the machine. I'm betting their cap died. They said lots of smoke from the box. I havnt gone down to check it out yet or check the motor.

I will forward the repair info to them that it's basically a cap in a box.

That PAM is my first exposure to phase converters.

 

[Deerhurst]

It is standard practice when using an RPC to not use the wild leg to power transformers and/or electronics, only use it to power the 3rd phase of the motor leg. The other two legs are pass through and would be either directly power the contactors or when using a transformer do not connect the wild leg to the transformer. Most RPC sites have recommendations as to RPC size for motor load, in general you need an RPC idler 2X the largest motor it will be used for.

Hmm. Guess I'm going to have to trace things with a meter once I get it off the trailer and make sure the same legs are always running contactors in the cabinet. I think I have the electrical schematics in the cabinet. Will check when it is unloaded. (Kinda hope they are dated so I can see how old this machine is)

Speaking of sizing, I think I read somewhere that each additional motor being run kinda stacks a little to the capacity of the RPC. If I get a 7.5hp I could run my 2 and 3hp motors with no issues as long as I fire up the 3hp first. Is this correct?


Also, as far as making my own, I've found basic schematics and some inexpensive kits for the converter box but a motor is needed. Any recommendations on this? How do I choose a motor to make a RPC?

 

[Deerhurst]

Going larger doesn't cause problems except adding to your power bill and initial cost. ( And giving you more excuses to buy bigger machines) it also allows using multiple machines at the same time. Just keep in mind total load on your shop feed lines.

I've run both static and rotary phase converters ( still do), you have to be careful with placement of the third "wild" leg always.

I think my mill is well big enough!!

Any thoughts on what is better? Static or rotary?

 

[dalmatiangirl61]

When I got there to see why their lathe wasn't spinning I found they had the 220 in spread across one input pin and one output pin and the 3 phase out scattered too and had been trying to power the machine. I'm betting their cap died. They said lots of smoke from the box. I havnt gone down to check it out yet or check the motor.

I will forward the repair info to them that it's basically a cap in a box.

That PAM is my first exposure to phase converters.

Mine has 3 wires, T1, T2 and T3, 220v in/out goes to T1 and T2, T3 is the artificial leg, don't ask me, it works. To be clear, there is not dedicated input/output sides.

 

[hvnlymachining]

I think my mill is well big enough!!

Any thoughts on what is better? Static or rotary?

Static does not provide three phase power, just third leg starting. So you only get about 50% of your motor stated HP. Rotary gives constant three phase power, so it's by far better for any motor that will be used above that half capacity. Also static can't be used for hard starting motors like pumps or non clutched lathes.
The only machines we use static phase converters on are shapers and Bridgeport type mills. I far prefer rotary for the lathes.

 

[Mark R. Williams]

I recently picked up my first piece of equipment to start my home shop and Im trying to figure out a phase converter. I am planning to add a lathe eventually.

I have a Bridgeport with a 2hp spindle and a 3hp hydraulic pump (synchro trace 2). It has an electronics cabinet and all the motors are controlled by the main panel so no VFDs. Im thinking I should be looking at a 7.5hp converter at minimum? Does this sound right?

Im thinking a rotary is best for my application (eventually want to wire it into the shop for each machine as I wont be able to run multiples at one time) vs a static. I know of a phase a matic that popped magic smoke with a small lathe on it (a question for later) and Im worried that the faux 3rd leg may cause issues with the contactors on my machine.

I see many recommendations for American Rotary here. I will be calling or emailing them soon to see what they say.

Any pointers, directions, etc would be much appreciated.

I have a RONK-CON rotary transformer rated for 20 KVA Max has the whole setup mounted to a pallet. It was purchased to install on a shop to feed the whole shop 3 phase panel but they ended up scrapping the project before we installed it so it never got installed, I'd gladly sell it.

 

[Deerhurst]

Static does not provide three phase power, just third leg starting. So you only get about 50% of your motor stated HP. Rotary gives constant three phase power, so it's by far better for any motor that will be used above that half capacity. Also static can't be used for hard starting motors like pumps or non clutched lathes.
The only machines we use static phase converters on are shapers and Bridgeport type mills. I far prefer rotary for the lathes.

Sounds like rotary might be in my best interest with the hydraulic pump then. I don't know when I'd ever use a full 2HP on the spindle. I doubt I've ever gotten close on the series 1 machines at work.

I did stall the lathe once when it got stuck engaged for threading. Was quite the crash. Needless to say that lathe is never to be used for threading again. It was questionable before that happened. I'll go use the Hardinge next door for threading.

 

[Deerhurst]

I have a RONK-CON rotary transformer rated for 20 KVA Max has the whole setup mounted to a pallet. It was purchased to install on a shop to feed the whole shop 3 phase panel but they ended up scrapping the project before we installed it so it never got installed, I'd gladly sell it.

Feel free to PM me. Don't think I'll need anything quite that big but I know others looking for rotary units too with much more tools than me.

 

[Deerhurst]

Talked to American Rotary. They recommended the ADX10. They said that is due to the pump and said it should handle pump startup loads better.


Thoughts?