Rotary phase converter sizing question

[Warren Lake]

Id listen to the people who build the stuff I think the manual for the rotos I bought is over 10 pages long. A planer is not hard start compared to things they had to power. The company I had picked made Rotos for the mennonites and farm areas where they didn't have three phase. The three choices allowed you to pick what was best and you could do more over and above. Hard start 10HP started fine with 10HP roto and ran under full load fine. Each manufacturer is different. The old ones were massive heavy motors, the newer ones or some lighter higher efficiency motors.

[Andrew Hughes]

Id listen to the people who build the stuff I think the manual for the rotos I bought is over 10 pages long. A planer is not hard start compared to things they had to power. The company I had picked made Rotos for the mennonites and farm areas where they didn't have three phase. The three choices allowed you to pick what was best and you could do more over and above. Hard start 10HP started fine with 10HP roto and ran under full load fine. Each manufacturer is different. The old ones were massive heavy motors, the newer ones or some lighter higher efficiency motors.

Warren the roto kinda looks similar to a Kay Rpc. I would bet a box of Daniel Webster cigars they are made by Phasemaster. Or maybe it’s justbthe look of a U frame motor.
Good Luck

[Warren Lake]

Delta TME is gone now which is sad. Likely around 50 years and absolute pros. I was given one of their rotos a 3Hp roto from the wife of one of the cabinetmakers I knew years after buying some of his machines I took it in once and a lady changed out some caps. I think it had 25 years on it at the time. When I bought I bought the same company but with a few gizos, voltage regulation one of them I remember, it kicks in a bank of caps under load then clics out not needed.

[Larry Edgerton]

The caps on my 50 hp are scary! Would not want to get hit by one of those.

I never have checked draw at idle Warren. Its not on idle long because it makes an obnoxious growl at idle.

[Michael Schuch]

A comment for those of you who are running "technically undersized" rotary phase converters. One fact to know is that many machine motors may not ever require the full amount of current rated on the motor (i.e. full load amps). This depends on what kind of machine it is and what you are trying to do with it. For example, a 5HP table saw that is rated at about 16 full load amps will only require about 1300 watts when just spinning the blade. A 16 amp full load would be about 3750 watts. But if you are pushing through some 2" dense hardwood, the current draw will definitely go up. Various machines machine pull different "actual current" depending on what kind of machine it is. One machine that will definitely pull "full load amps" is your dust collector when all blastgates are open.

I agree. My 16" saws (2 radial arm saws [both 7.5hp] and 2 table saws [One 7.5hp and one 5hp]) come no where near pulling full current and start/run easily on my RPC.

When I think of a heavy starting load I think of an air compressor. Even a planer isn't doesn't really start under load.

I built my balanced 10hp idler rotary phase converter over 30 years ago specifically to run my 16" 1947 Redstar radial arm saw. It has handled my RAS admirably as well as every other 3 phase machine I have purchased since then. Most of my machines get converted to VFD's but all of them get plugged into my VFD and run while waiting for a VFD install.

[Warren Lake]

past the heavy duty models were higher than normal amps fof submersible pumps and sealed unit refrigeration. Agree the planer is not hard start the 3Hp roto with no gizmos started and ran the combo machine 3Hp easily and the shaft is a planer, a saw and a mortiser and still not hard start.