I have an old Monarch with a 15 horse motor. To this point I've been running it with an old 10 horse VFD that was given to me. This VFD is designed specifically for converting single phase to three phase. It starts my lathe motor just fine and will run most of the gears in the lathe except the top two or three speeds. I am planning a RPC build to power the shop so I can add more three phase equipment down the road with less hassle. Because I'm worried about the inrush issues of starting a 25-30 hp rotary deal, my plan is to run a dual idler setup. I'm going to cap start the first 15 horse motor and use that to start the second 15 horse idler. I'm not afraid of the added complexity and I have basically unlimited access to used components. Is this a dumb idea right from the start? I've read a bunch but haven't seen anybody specifically build a dual idler setup this way. I know guys will start other equipment on the line to add potential, but never a dual idler. I know I could pony start a 25 or 30 horse too and that may be an option if my dual idler doesn't pan out or if you guys think its a horrible idea.
The real reason for this post: The first idler I acquired for the idler is a 15 horse marathon that had an input bearing going out. I brought it home and put new bearings in it. Last night, just for fun, I wired my 10 horse VFD up to it just so that I could hear it run and see how loud it would be in my shop. It's a typical 9 lead motor and I had it wired for low voltage. The drive did this really funny sounding two-step start up when I first fired the idler. I immediately shut it off and double checked everything. Started it again and same thing. Two-step start up. I checked the RPM of the motor with a tach and it's spinning about 1800 rpm like it should. Then I noticed that the readout on my VFD was showing 10 amps just idling this 15 horse motor. My 15 horse lathe motor idles at like 2 or 3 amps with four belts on it. At his point I was getting a little confused. I took the motor out of service before putting bearings on it and it was a functional motor. It spins plenty freely by hand. Why the high idle amps? So at this point I wired the motor for high voltage just out of curiosity. The drive started it fine again, still with the two step thing going on, only this time idle amps were down to 2-3 just like the old motor in my Monarch. I'm 99% sure I wired the motor in my Monarch correctly for low voltage. It's a real nightmare to double check because of how tight it is in there. I never really checked now that I think of it what the drive outputs for voltage. I just assumed 220 in so about 220 out. I can't imagine the monarch would run as good as it does on low voltage if I've had it wired wrong this whole time. Any thoughts?? I'll check the drive when I get home to see what it outputs for voltage. I would be really surprised if it wasn't 220.
The real reason for this post: The first idler I acquired for the idler is a 15 horse marathon that had an input bearing going out. I brought it home and put new bearings in it. Last night, just for fun, I wired my 10 horse VFD up to it just so that I could hear it run and see how loud it would be in my shop. It's a typical 9 lead motor and I had it wired for low voltage. The drive did this really funny sounding two-step start up when I first fired the idler. I immediately shut it off and double checked everything. Started it again and same thing. Two-step start up. I checked the RPM of the motor with a tach and it's spinning about 1800 rpm like it should. Then I noticed that the readout on my VFD was showing 10 amps just idling this 15 horse motor. My 15 horse lathe motor idles at like 2 or 3 amps with four belts on it. At his point I was getting a little confused. I took the motor out of service before putting bearings on it and it was a functional motor. It spins plenty freely by hand. Why the high idle amps? So at this point I wired the motor for high voltage just out of curiosity. The drive started it fine again, still with the two step thing going on, only this time idle amps were down to 2-3 just like the old motor in my Monarch. I'm 99% sure I wired the motor in my Monarch correctly for low voltage. It's a real nightmare to double check because of how tight it is in there. I never really checked now that I think of it what the drive outputs for voltage. I just assumed 220 in so about 220 out. I can't imagine the monarch would run as good as it does on low voltage if I've had it wired wrong this whole time. Any thoughts?? I'll check the drive when I get home to see what it outputs for voltage. I would be really surprised if it wasn't 220.