Running a Bandsaw Mill on a Three-Phase Converter
From contributor B:
Yes, you can run an LT300 3ph mill from a single phase electric service using a 3ph converter. We have an LT40 with a 25hp 3ph motor that we are running using a 50hp 3ph converter. Wood-Mizer worked with us and the people at RONK (the phase converter manufacturer we used) to select the right size converter for our application.
Wood-Mizer has wiring instructions for installing a phase converter and specs for fusing, etc. A Wood-Mizer salesman can send you the information or put you in touch with their electrical engineer to supply the details. They can even supply a phase converter.
From contributor C:
To contributor B: How many single phase amps are you using when sawing, using that converter? You must have a fairly big service there.
From the original questioner:
To contributor B: I was referring to single phase service. I wasn't sure if you could because of the 460 on the 30hp 3 phase.
From contributor B:
Iím not an electrician or electrical engineer so check my information before using it. The 25 hp motor on the mill is wired 208 (220) - not 460 - fused at 100 amps per phase. As we were wiring it up (had a qualified electrician doing the work) he was checking the amp reading per phase and I think it was pulling in the upper 70s amps running with no load. Youíll need to check for the 30hp motor on the LT300. Our 25 hp motor came wired 460 but could be re-wired 220v. Thatís what we did because thatís what we had coming in from the power company. The down side to wiring it 220 is that it takes a much larger cable, fuses, etc. to carry the amp load.
We also have a 10 hp 3ph edger that is fused 40 amps per phase. Itís run off the same converter. While we run them both at the same time, we are cautioned not to start both motors at the same time. The two motors sound better when they are both running. I think it has to do with balancing the three phase out.
The power company did come in and replace the transformer with a 50kVA unit. The transformer just services our saw shed Ė not our house or anything else. We have a 400 amp service entrance that has two 200 amp beakers. One side services all the three phase and the other goes to a regular 1ph panel that has all the lights, dust blower, plugs, etc.
Weíve been running this setup for over three years with no problems. But just this last August we had some times when there appears to be some diminished power. Weíve had momentary loss of power too. Iím sure itís something to do with the peak overloads of the whole power grid in the hot weather. The weather has been cooler the last couple of weeks and weíre back to normal now.
From contributor D:
Most phase converters require 200 amp service. If you only have 220/240, you will have to get step up converters to boost the voltage to 460 and then convert that to 3 phase. The LT300 requires 100 amp service to run. The phases cannot have more than a 2% differential between phases and the 460 cannot be less than 5% and no more than 10% of the 460.
From contributor E:
We recently went through the adventure of hooking up an LT-300 to a phase converter. We had a 480 volt single phase service from the power company. A couple of things came up in the process.
1. Make sure the power company hangs a 100KVa transformer on the pole.
2. If you hire out the building of the phase converter be cautious. Our original one was made by a fellow who had been doing it for years. However, he had been doing it for old circle mills and the generated leg was always kept away from any control circuitry. In the LT-300 there are some AC motor controllers that use all 3 phases and you canít have a high voltage in the generated leg. We finally found some folks who build phase converters for CNC machines and theirs seem to be working fine.
3. You will probably want to size the idler motor at 1.5 to 2 times the size of the biggest motor you have to start. After you get it started you can have 2 to 3 times the size of the idler motor in total horsepower of all the motors supplied. The LT-300 has a 30 HP motor, our edger is 30 HP, our air compressor is 10 HP, the hydraulic motor is 7.5 HP, there is a myriad of 2 and 3 HP motors for belts and chains all 3 phase. We are supplying them with one 75 HP idler motor.
4. Make sure you find a good industrial electrician.
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