nickwigen
New User
- Location
- West Linn Oregon
- Occupation
- Mech Engineer Emeritus ;o)
We had a problem with our Makino S56 after we relocated our shop from an industrial park with 120/208 3-phase to a rural location with single phase power. My searches took me to this site, specifically the thread:
I am used to seeing forums rich on opinion and poor on knowledge so it was a pleasant surprise to find good, qualified information. (I have 40+ years experience as a mechanical engineer and have work on many industrial projects with mostly 460 3-phase so I consider myself knowledgeable but NOT expert around power.)
We installed an American Rotary ADX 60 RPC. The 60 is for 60 hp.
The Makino has 4 motors:
X, Y & Z axis positioners 5.4 hp each
One spindle 18 hp.
After checking out the new RPC power we ran some tests on the Makino with no problems. We put it to work on a job and everything was fine for about an hour. During the hour it went through several tool changes with spindle start/stops etc. At the end of the operation during the spindle stop we heard a bad noise and the spindle coasted to a stop. We got a fault message of a spindle motor failure. The spindle motor on the S56 is integrated into the spindle cartridge as opposed to a typical c-face motor. The spindle turned freely without any bad bearing sounds.
We tested the resistance of the 3 motor leads to ground. Two tested open but the third had continuity to ground. I think this is a bad sign.
The spindle cartridge is on the way to a rebuild facility in Detroit that specializes in this work. They can rewind the motor if necessary. Once it gets there we will get a report of what they find.
Now to the electrics. We don't want to make another expensive noise...
The previous shop was standard 3 phase wye with the grounded neutral. the power from the load center to the Makino was 3 wire with a ground. No neutral.
The output from the RPC is a delta configuration. Here is what we measure:
Leg to Leg is 229 to 233 volts. Pretty balanced.
Legs to ground are: 115, 115 and 195. From what I understand this is not unusual and not necessarily a problem.
Should be install an isolation transformer to convert the 230 volt delta to 120/208 Wye? The Maddox 45 kva we are looking at has multiple taps so we can drop the 233 down to 208. Our thinking that this will duplicate the conditions at the old shop. A transformer is a bit expensive but nothing like spindle motors + lost production. Many thanks for any help.
Grounding delta delta transformers on CNC machines
We have several CNC machines that are ungrounded. Most have 480/240 delta delta transformers sitting right on the machine. We have been told by Mitsubishi, Fanuc, and other machine tool technicians that is part of a problem we have been having with NC units going bad. I will order or machine...
forums.mikeholt.com
I am used to seeing forums rich on opinion and poor on knowledge so it was a pleasant surprise to find good, qualified information. (I have 40+ years experience as a mechanical engineer and have work on many industrial projects with mostly 460 3-phase so I consider myself knowledgeable but NOT expert around power.)
We installed an American Rotary ADX 60 RPC. The 60 is for 60 hp.
The Makino has 4 motors:
X, Y & Z axis positioners 5.4 hp each
One spindle 18 hp.
After checking out the new RPC power we ran some tests on the Makino with no problems. We put it to work on a job and everything was fine for about an hour. During the hour it went through several tool changes with spindle start/stops etc. At the end of the operation during the spindle stop we heard a bad noise and the spindle coasted to a stop. We got a fault message of a spindle motor failure. The spindle motor on the S56 is integrated into the spindle cartridge as opposed to a typical c-face motor. The spindle turned freely without any bad bearing sounds.
We tested the resistance of the 3 motor leads to ground. Two tested open but the third had continuity to ground. I think this is a bad sign.
The spindle cartridge is on the way to a rebuild facility in Detroit that specializes in this work. They can rewind the motor if necessary. Once it gets there we will get a report of what they find.
Now to the electrics. We don't want to make another expensive noise...
The previous shop was standard 3 phase wye with the grounded neutral. the power from the load center to the Makino was 3 wire with a ground. No neutral.
The output from the RPC is a delta configuration. Here is what we measure:
Leg to Leg is 229 to 233 volts. Pretty balanced.
Legs to ground are: 115, 115 and 195. From what I understand this is not unusual and not necessarily a problem.
Should be install an isolation transformer to convert the 230 volt delta to 120/208 Wye? The Maddox 45 kva we are looking at has multiple taps so we can drop the 233 down to 208. Our thinking that this will duplicate the conditions at the old shop. A transformer is a bit expensive but nothing like spindle motors + lost production. Many thanks for any help.
