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GE 3 phase motor help

aau10

Plastic
Joined
Feb 13, 2017
I just purchased a Hardinge dv-59 lathe that I want to power with a VFD. My question is about the motor. It is a GE 2-speed, mod 5k204a3908, 220v 3ph. The plate says 2.2/2a, 1680/840 rpm, 7.5/3.75hp. The current listed seems more for a .75/.375hp as a 7.5hp usually is in the 15a range. This would make a big difference in the required VFD. Could the plate be wrong on the current or hp? This seems to be a small lathe for a 7.5 hp motor. Any clarifacition would be appreciated.
 

Bill D

Diamond
Joined
Apr 1, 2004
Location
Modesto, CA USA
No result for that model #. Check for overload/fuse amps.
Motor length, diameter, shaft diameter. Is the supply wire more then #12 AWG? A 7.5hp motor will weigh near 100 pounds.
Bill D
 

L Vanice

Diamond
Joined
Feb 8, 2006
Location
Fort Wayne, IN
The first DV-59 lathes were made in 1946. They, and other Hardinge lathes and mills of the 1935-1960 era, usually had 2-speed motors with 3/4 or.75 HP at ~1725 RPM and 3/8 or .375 HP at ~850 RPM with slight variations in rated speed depending on the motor maker. Here is a picture of a typical circa 1944 Hardinge lathe motor nameplate.

1653966706646.jpeg

Looks like your decimal points were misplaced.

I run several Hardinge lathes and mills in my shop with this type motor from a rotary phase converter. I have used a 110 V input/220 V output 1 HP capacity VFD to test run a Hardinge lathe motor wired only to the high speed. You can dial down to 30 HZ to get the half speed/half power low speed feature, so there is no need to use the low speed winding with a VFD. Running from a 110 V outlet can be very convenient and avoids having to supply a 220 V circuit for a low power (1 HP or less) three phase motor.

Larry
 
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wood2steel

Cast Iron
Joined
May 17, 2013
Location
georgia
Aau10, I will check my 16" Southbend in the morning. It has a 2 speed 3 hp/1.5 hp motor (GE, if I recall). Not sure if you will be successful running the vfd on that motor. Most of those were dual winding design and built with a lot less insulation than usual. Had a big issue with motor overheating if the rpms were reduced much for extended periods. Finally put mine back on a std converter. Send a PM with your contact info if you need me to talk you through any of the scenarios I encountered. I had also talked with the company Tech support regarding the motor high/low speed winding design. Good Luck
Johnny
 

texasgeartrain

Titanium
Joined
Feb 23, 2016
Location
Houston, TX
Aau10, I will check my 16" Southbend in the morning. It has a 2 speed 3 hp/1.5 hp motor (GE, if I recall). Not sure if you will be successful running the vfd on that motor. Most of those were dual winding design and built with a lot less insulation than usual. Had a big issue with motor overheating if the rpms were reduced much for extended periods. Finally put mine back on a std converter. Send a PM with your contact info if you need me to talk you through any of the scenarios I encountered. I had also talked with the company Tech support regarding the motor high/low speed winding design. Good Luck
Johnny
I forget the "why's", but I was also thinking a 2 speed motor should not be run by vfd.

2 speed motors are more expensive, and not as easy to come by as regular 3 phase motors too.
 

technocrat

Hot Rolled
Joined
Feb 9, 2009
Location
Oz
I forget the "why's", but I was also thinking a 2 speed motor should not be run by vfd.
You basically need two setups in the vdf for each of the speeds and ideally some way to switch the config automatically. Old motors really are not good to use with VFD's due to poor insulation and bearing overspeed. VFD's can put a lot more energy into the motor windings and also run faster than phase sync speed. Now there VFD duty motors available than expect this usage and you might be better replacing with a single speed VFD duty motor and wiring.
 

L Vanice

Diamond
Joined
Feb 8, 2006
Location
Fort Wayne, IN
You basically need two setups in the vdf for each of the speeds and ideally some way to switch the config automatically. Old motors really are not good to use with VFD's due to poor insulation and bearing overspeed. VFD's can put a lot more energy into the motor windings and also run faster than phase sync speed. Now there VFD duty motors available than expect this usage and you might be better replacing with a single speed VFD duty motor and wiring.
The above is why I connected the VFD only to the high speed winding, treating the two-speed motor as a single speed motor. The trouble with replacing the motors in old Hardinge machines is that they are not a modern frame size. The shafts are 3/4 inch, not available on modern motors, and the mounting dimensions are also different. There is no actual need to run them over 60 HZ and running them at 30 HZ results in the same power and speed as running the low speed winding at 60 HZ. So keeping the old motor is just a lot simpler. And it works.

Larry
 

JST

Diamond
Joined
Jun 16, 2001
Location
St Louis
It looks as if the "7" may be a "1". A 1/2 HP is 2.2A at 230V per the UL "standard ratings".
 

Bill D

Diamond
Joined
Apr 1, 2004
Location
Modesto, CA USA
Test post: The main page index says NA for last post. Been that way for several hours that I know of.
It did not move up when he posted or for my post. It is down below less current posts. So the updates are not being noticed/dated/time by the sorter function
Bill D
 
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rons

Diamond
Joined
Mar 5, 2009
Location
California, USA
Could the plate be wrong on the current or hp? This seems to be a small lathe for a 7.5 hp motor. Any clarifacition would be appreciated.
Probably it was almost the end of shift and the Scribe was getting tired and misplaced the dots. Sometimes it can get confusing because
the size of motor housings for old 1Hp motors are as big as 5 or 7Hp. You can verify the current by connecting two motor leads to 220vac single
phase and spin the rotor with a rope. Use a meter to monitor current.
 

Froneck

Titanium
Joined
Dec 4, 2010
Location
McClure, PA 17059
Usually a 2 speed motor is single voltage only. I have never see a 2 speed motor that is dual voltage but it is possible but the number of wires needed will greatly increase. I have run quite a few machines that are 480VAC 3 phase with 240VAC single phase. I did do it on a large 10HP motor some time ago with a single phase 480 transformer connected to 3 phase RPC. But now I'm running smaller HP motors with the RPC connected to a 3 phase transformer, one being a 2 speed motor on a Moore Jig Borer other is a Gorton MasterMill will single speed motor.They work great without any problems.
I have gotten a few transformers from HGR cheap but not sure if they will be very cheap now since their sale to another company.
 

jim rozen

Diamond
Joined
Feb 26, 2004
Location
peekskill, NY
I think hardinge did make some 9 wire dual voltage, 2 speed motors. Others will have a better story about this.

1) wire the motor to high speed.
2) use a VFD. Don't go much above 60 Hz.
3) don't throw out the switchgear as you may wind up with 3~ power or sell the machine to somebody who does.
 

mksj

Cast Iron
Joined
Aug 10, 2010
Location
Tucson, AZ
A 7.5 Hp motor would be huge compared to a a 0.75Hp, and much heavier. Size should be obvious as to 7.5 vs. .75Hp.

With 2 speed motors, there are different variables as to the winding selection for use with a VFD. If constant Hp, I use the low speed setting otherwise I usually use the high speed setting. Some dual speed (Asian) motors that I have wired to VFD's did not run well on either speed no matter how I programmed the VFD, others have run just fine on a fixed speed. In some cases I have setup the VFD's dual motor function and used a switch to both change the motor wiring configuration and VFD settings with a lock-out. End of the day it was not worth the trouble, tossed the motors and put in a vector motor which performed much better.
 

Jraef

Titanium
Joined
Aug 10, 2004
Location
San Francisco Bay Area
If a 2 speed motor is constant HP, the Hp on the nameplate is the same in either speed.

When the HP value on the nameplate is different, you can just hook up the VFD to the high speed configuration, there is no need to use the low speed once you have the VFD.

For 230V there is a low risk of damaging the motor from using a VFD. If you are worried about it because the motor is special, add a dV/dt filter to the output of the VFD.
 








 
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