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Metalworking (rec.crafts.metalworking) Discuss various aspects of working with metal, such as machining, welding, metal joining, screwing, casting, hardening/tempering, blacksmithing/forging, spinning and hammer work, sheet metal work. |
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#1
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VFD won't work on lathe, Why?
Wayne wrote: I'm having a Leeson VFD (Model #174273, leeson.com) installed on a lathe by the seller. It has 220v sgl phase in. I purchased the VFD separately. I know they have experience with VFD's. A service tech working for a drive manufacturer was also there and helped out. I don't think I clearly understood the issue, but here goes... They tell me that the motor doesn't have any torque. They also said that the VFD would need to know what gear range the lathe is in in order to work properly. The motor is not a VFD rated motor. They are uncomfortable selling the lathe with the VFD because of the poor performance. The first guess is the motor is still wired for 440 Volts, and needs to be changed over for 220 V. Assuming the motor is a 220/440 V motor, this should be easy to check, and easy to fix. I assumed as long as I kept the VFD @ 60 hz, I could use the gear ranges on the lathe as if it was hooked up to a normal 3 phase power line. Then I could make small speed adjustments. I did ask if I bought a VFD rated motor if they thought this would solve the issue. It sounded like it would help, but still not work right. Why the heck not? If a good motor, of correct voltage, RPM and HP is installed, it HAS to work! I'm getting Leeson to contact them. I've done searches for VFD information in this NG before I bought. I never heard of anyone having an issue like this. Or having a motor that wouldn't work with a VFD. Yup, I HAVE heard of this before. But, there was usually a reason for it. Either the motor was set for the wrong voltage, was a dual-speed motor or some other complication. All I can say, is I have done this on a Sheldon 15" lathe, and it worked like a DREAM! In this case, it is a Tosvert A5 VFD, a pretty fancy unit, and a bit larger than actually needed. I get variable speed, very slow jog for getting gears to engage, and dynamic braking to stop the chuck like it had a brake. Make sure you get braking resistors in your setup, it makes a real difference on a lathe. Anyway, I can't explain the problem, but I'm pretty sure they are doing SOMETHING wrong, there. If the lathe has a dual speed motor, that really complicates the wiring, and I can understand how they are getting confused. Jon |
#2
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VFD won't work on lathe, Why?
I'm having a Leeson VFD (Model #174273, leeson.com) installed
on a lathe by the seller. It has 220v sgl phase in. I purchased the VFD separately. I know they have experience with VFD's. A service tech working for a drive manufacturer was also there and helped out. I don't think I clearly understood the issue, but here goes... They tell me that the motor doesn't have any torque. They also said that the VFD would need to know what gear range the lathe is in in order to work properly. The motor is not a VFD rated motor. They are uncomfortable selling the lathe with the VFD because of the poor performance. I assumed as long as I kept the VFD @ 60 hz, I could use the gear ranges on the lathe as if it was hooked up to a normal 3 phase power line. Then I could make small speed adjustments. I did ask if I bought a VFD rated motor if they thought this would solve the issue. It sounded like it would help, but still not work right. I'm getting Leeson to contact them. I've done searches for VFD information in this NG before I bought. I never heard of anyone having an issue like this. Or having a motor that wouldn't work with a VFD. I'm puzzled, anybody have any ideas? Thanks, Wayne |
#3
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VFD won't work on lathe, Why?
Something else is wrong, maybe with the VFD.
When the VFD is set at 60 hz., the motor should put out essentially the same power as if it was running from "power company" 3 phase. If that's not happening, something is fundamentally wrong with the motor, the VFD or the way its hooked up or configured. In my experience a "VFD rated motor" is not required. There's tons of people running ordinary motors with VFD's with no problem, and I've never heard of a specific problem traced to the use of a "non-VFD motor". If anyone had's such a problem, please speak up. Keep in mind you do lose significant power as you get away from 60 hz. on the VFD. Depending on your motor, somewhere between 5 hz and 10 hz you go down to zero power. On my 2HP (non-vfd) motor on my lathe, I get some usable torque at 10 hz. so thats the lowest speed I allow. I don't do any heavy cutting at that speed but its useful for tapping, in fact I like the limited torque for that usage. At 30 hz. you'll be a little less than half power. Also as you go up in speed over 60 hz. you lose power. At double speed (120 hz.) I believe you're down to about 1/3 full power. I do mostly prototype work and small run production work, so I'm not pushing my machines to the max. So for both my lathe and mill, the 2HP motor through the VFD gives me plenty of power running my VFD from 10 hz. to 120 hz., although most of the time I'm in the range of 30 hz. to 90 hz. I hardly every change the belt position on the mill and I usually only go in the back gears on the lathe when tapping. However, if you have jobs where you need to run the motor for a long time at lower speeds with some load on it, you need to put an extra fan on it. Most people get a 6" "pancake" fan and tie wrap it or wire it on the end of the motor. If you want to get fancy, put a thermal "snap" switch on it so it only turns on when the motor gets hot. I haven't even bothered to do that yet since most of my low speed work is one offs. So find out if the machine seems to be putting full power out with the VFD set at 60 hz., if not, something fundamental is wrong with the VFD, the motor or the machine itself. Good luck- Paul T. |
#4
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VFD won't work on lathe, Why?
Make sure you get braking resistors in your setup, it makes
a real difference on a lathe. Jon is dead on with this suggestion, the braking resistors work great on both my lathe and mill. I never touch the brake on the mill anymore except to change tooling. Paul T. |
#5
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VFD won't work on lathe, Why?
"Paul T." wrote in message ... Something else is wrong, maybe with the VFD. When the VFD is set at 60 hz., the motor should put out essentially the same power as if it was running from "power company" 3 phase. If that's not happening, something is fundamentally wrong with the motor, the VFD or the way its hooked up or configured. In my experience a "VFD rated motor" is not required. There's tons of people running ordinary motors with VFD's with no problem, and I've never heard of a specific problem traced to the use of a "non-VFD motor". If anyone had's such a problem, please speak up. No personal experience of problems, but the reason why VFD rated motors are specified is that the high frequency switching waveform used in the VFD causes high voltage spikes to appear on the motor as a result of the high dV/dT and the motor's inductance; this can destroy the insulation on a non-VFD rated motor. Aside from the insulation, there should be little or no difference in performance. Martin. -- martindot herewhybrowat herentlworlddot herecom Keep in mind you do lose significant power as you get away from 60 hz. on the VFD. Depending on your motor, somewhere between 5 hz and 10 hz you go down to zero power. On my 2HP (non-vfd) motor on my lathe, I get some usable torque at 10 hz. so thats the lowest speed I allow. I don't do any heavy cutting at that speed but its useful for tapping, in fact I like the limited torque for that usage. At 30 hz. you'll be a little less than half power. Also as you go up in speed over 60 hz. you lose power. At double speed (120 hz.) I believe you're down to about 1/3 full power. I do mostly prototype work and small run production work, so I'm not pushing my machines to the max. So for both my lathe and mill, the 2HP motor through the VFD gives me plenty of power running my VFD from 10 hz. to 120 hz., although most of the time I'm in the range of 30 hz. to 90 hz. I hardly every change the belt position on the mill and I usually only go in the back gears on the lathe when tapping. However, if you have jobs where you need to run the motor for a long time at lower speeds with some load on it, you need to put an extra fan on it. Most people get a 6" "pancake" fan and tie wrap it or wire it on the end of the motor. If you want to get fancy, put a thermal "snap" switch on it so it only turns on when the motor gets hot. I haven't even bothered to do that yet since most of my low speed work is one offs. So find out if the machine seems to be putting full power out with the VFD set at 60 hz., if not, something fundamental is wrong with the VFD, the motor or the machine itself. Good luck- Paul T. |
#6
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VFD won't work on lathe, Why?
In my experience a "VFD rated motor" is not required. There's tons of people running ordinary motors with VFD's with no problem, and I've never heard of a specific problem traced to the use of a "non-VFD motor". If anyone had's such a problem, please speak up. No personal experience of problems, but the reason why VFD rated motors are specified is that the high frequency switching waveform used in the VFD causes high voltage spikes to appear on the motor as a result of the high dV/dT and the motor's inductance; this can destroy the insulation on a non-VFD rated motor. Aside from the insulation, there should be little or no difference in performance. Martin. I concur with Martin from personal experience. At work we fried a few motors and traced the problem back to being non-rated motors for VFD use. In working with the motor reps he confirmed that insulation is the difference. The motors that we fried were running 24x7 and would only last a month or two before failing so in limited machine tool use it should not be a problem. lg no neat sig line |
#7
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VFD won't work on lathe, Why?
what they are telling you makes no sense. if the motor is a 3 phase 220V
motor, AND you hook it correctly to a VFD, AND you plug the VFD into 220, the motor ought to work properly. There is no reason why the VFD need to know gear ratio unless you expect the VFD display to read out in RPM. as others have said, a VFD will drive pretty much any 3 phase motor, and in home use, there seems to be no problem. You are getting the run-around. "Wayne" wrote in message om... I'm having a Leeson VFD (Model #174273, leeson.com) installed on a lathe by the seller. It has 220v sgl phase in. I purchased the VFD separately. I know they have experience with VFD's. A service tech working for a drive manufacturer was also there and helped out. I don't think I clearly understood the issue, but here goes... They tell me that the motor doesn't have any torque. They also said that the VFD would need to know what gear range the lathe is in in order to work properly. The motor is not a VFD rated motor. They are uncomfortable selling the lathe with the VFD because of the poor performance. I assumed as long as I kept the VFD @ 60 hz, I could use the gear ranges on the lathe as if it was hooked up to a normal 3 phase power line. Then I could make small speed adjustments. I did ask if I bought a VFD rated motor if they thought this would solve the issue. It sounded like it would help, but still not work right. I'm getting Leeson to contact them. I've done searches for VFD information in this NG before I bought. I never heard of anyone having an issue like this. Or having a motor that wouldn't work with a VFD. I'm puzzled, anybody have any ideas? Thanks, Wayne |
#8
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VFD won't work on lathe, Why?
I have had a vfd on my lathe 15x40 lathe and my mill for at least 10
years.Single phase in 3 phase out. And I have never had a proplem with it . I have never had a problem with torque.In fact I rarely change gears I keep my lathe in high gear.I have the vfd set for 0 to 120 hertz.that will give me a speed range from 0 rpm to 2400 rpm.But I usually don't go past 60 hertz (1200 rpm).I can drill a hole at 1000rpm and turn the speed knob to 80 rpm and tap a 1/2 -13 thread in high gear. I have been reading this news group every day for many years and I never heard of someone losing a motor to a vfd. |
#9
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VFD won't work on lathe, Why?
On Wed, 09 Jun 2004 02:24:54 GMT, "william_b_noble"
wrote: I'm having a Leeson VFD (Model #174273, leeson.com) installed on a lathe by the seller. It has 220v sgl phase in. I purchased the VFD separately. I suspect I see the problem...... Gunner "A vote for Kerry is a de facto vote for bin Laden." Strider |
#10
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VFD won't work on lathe, Why?
In article ,
larry g wrote: ....... difference. The motors that we fried were running 24x7 and would only last a month or two before failing so in limited machine tool use it should not be a problem. I am curious; What voltage were these motor running on?? Someone reported that normal 230V motors seem to hold up well running from a VFD, but higher voltage motors do not. So I am curious if your failures support of disprove this theory. chuck |
#11
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VFD won't work on lathe, Why?
what they are telling you makes no sense.
Well I'm not so sure. Here is a similar personal experince. I installed a 2HP Teco VFD on a rockwell 11x25 lathe with a 1HP rockwell motor. This lathe also had a mechanical variable speed drive. With the stock motor it would not start if the mechanical VS was set above 800RPM. The motor simply did not have enough torque to overcome the drag and inertia of the VS drive and spindle. I changed some parameters in the VFD to increase the starting torque and made it work pretty well. The caveat is that the motor would probably burn out if operated at low speed with the amount of low RPM torque boost I programmed in. I have sense changed the motor to a 2HP Leeson inverter duty motor and it runs extreamly well without any torque boost. I also replaced all bearings on both jackshafts because they were dry. This may have been part of the original problem. I now have two leeson inverter duty motors and I believe they are an excellent value. I paid 150 for a 2HP inverter duty motor from an on line supplier. electric motor warehouse or something like that. chuck |
#12
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VFD won't work on lathe, Why?
Hmmmm...now that brings up a question. If the VFD is set in a soft
start mode and the gearbox on the lathe is engaged you are essentially starting the motor loaded at the low end of the HZ range which means little to no torque. I would anticipate the thing wouldn't get going or would have problems getting past the low speeds. (assuming the VFD is used as the starting device rather than just providing 3 phase to the machine) Can't remember the exact details of the original question though. Someone said here that a two speed motor would NOT work with a VFD. Not being all that good with motor electrics, I was wondering why this was. I was under the impression that 2 speed 3 phase motors simply energised the poles in the motor differently to achieve the second speed. My lathe has a 5 HP 2 speed and it would be nice to run it off the VFD simply because my current rotary convertor won't run it well on the low range (hates to start). It would be very difficult to change out the motor in this one and I don't have time to monkey around with it anyway. Koz Charles A. Sherwood wrote: what they are telling you makes no sense. Well I'm not so sure. Here is a similar personal experince. I installed a 2HP Teco VFD on a rockwell 11x25 lathe with a 1HP rockwell motor. This lathe also had a mechanical variable speed drive. With the stock motor it would not start if the mechanical VS was set above 800RPM. The motor simply did not have enough torque to overcome the drag and inertia of the VS drive and spindle. I changed some parameters in the VFD to increase the starting torque and made it work pretty well. The caveat is that the motor would probably burn out if operated at low speed with the amount of low RPM torque boost I programmed in. I have sense changed the motor to a 2HP Leeson inverter duty motor and it runs extreamly well without any torque boost. I also replaced all bearings on both jackshafts because they were dry. This may have been part of the original problem. I now have two leeson inverter duty motors and I believe they are an excellent value. I paid 150 for a 2HP inverter duty motor from an on line supplier. electric motor warehouse or something like that. chuck |
#13
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VFD won't work on lathe, Why?
On Wed, 09 Jun 2004 07:05:44 GMT, Gunner wrote:
On Wed, 09 Jun 2004 02:24:54 GMT, "william_b_noble" wrote: I'm having a Leeson VFD (Model #174273, leeson.com) installed on a lathe by the seller. It has 220v sgl phase in. I purchased the VFD separately. I suspect I see the problem...... Gunner Ooops...sorry..I was over tired and misread it. Disregard Gunner "A vote for Kerry is a de facto vote for bin Laden." Strider |
#14
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VFD won't work on lathe, Why?
The reason motors running on 230 are more resistant to voltage spikes is
that they are usually rated 230/460V and the insulation system is actually good for 600V. At least that is the case on quality Nema frame motors. Running at 230 gives a lot more safety margin to supply voltage spikes. Randy "Charles A. Sherwood" wrote in message ... In article , larry g wrote: ...... difference. The motors that we fried were running 24x7 and would only last a month or two before failing so in limited machine tool use it should not be a problem. I am curious; What voltage were these motor running on?? Someone reported that normal 230V motors seem to hold up well running from a VFD, but higher voltage motors do not. So I am curious if your failures support of disprove this theory. chuck |
#15
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VFD won't work on lathe, Why?
I believe the original poster stated that he was trying to use a VFD with a
SINGLE phase motor. That doesn't work. Most of the replies refered to THREE phase motors and their remarks are applical to that. Earle Rich Mont Vernon, NH |
#16
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VFD won't work on lathe, Why?
In article , Gunner says...
I'm having a Leeson VFD (Model #174273, leeson.com) installed on a lathe by the seller. It has 220v sgl phase in. I purchased the VFD separately. I suspect I see the problem...... The abbreviations were confusing, at first I also took that to read he had a single phase motor in the lathe. But I think he really means that the VFD he purchased is designed to run on 220 volt single phase in(put) power source. Jim ================================================== please reply to: JRR(zero) at yktvmv (dot) vnet (dot) ibm (dot) com ================================================== |
#17
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VFD won't work on lathe, Why?
In article ,
Koz wrote: [ ... ] Someone said here that a two speed motor would NOT work with a VFD. Not being all that good with motor electrics, I was wondering why this was. I was under the impression that 2 speed 3 phase motors simply energised the poles in the motor differently to achieve the second speed. My lathe has a 5 HP 2 speed and it would be nice to run it off the VFD simply because my current rotary convertor won't run it well on the low range (hates to start). It would be very difficult to change out the motor in this one and I don't have time to monkey around with it anyway. [ ... lots of HTML snipped from bottom of article ... ] O.K. My *opinion* on this is that the two-speed motors require switching the windings. VFDs should *not* be switched between the VFD and the motor, or you risk damaging the output transistors with voltage spikes. Normal practice is to ask the VFD to stop or start the motor. As far as I can see -- a two-speed motor should work fine with a VFD as long as you *always* remember to stop the motor with the VFD, switch the speeds, and then restart, so you are not switching an electrically-hot motor. The problem here is in *always* remembering to not switch the motor speed while it is running from the VFD. (Note that I am switching a 1HP motor being run from a 7-1/2 HP VFD, so with sufficient over-capacity, it seems to work, even for plug reversing. As for two-speed motors with the so-called static converters, such as Phase-o-Matic -- those are designed for a specific horsepower range to start the motor. Too large or too small a horsepower, and a given converter won't work. Since the switching of the windings changes the horsepower (by a factor of two, IIRC), switching the speed would produce a motor which would not start with the static converter, thus problems there, too. A good healthy rotary converter should handle the two-speed motor with no problems, and no need to remember to always stop the motor *before* switching the speed. Enjoy, DoN. -- Email: | Voice (all times): (703) 938-4564 (too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html --- Black Holes are where God is dividing by zero --- |
#18
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VFD won't work on lathe, Why?
In article ,
ERich10983 wrote: I believe the original poster stated that he was trying to use a VFD with a SINGLE phase motor. That doesn't work. Most of the replies refered to THREE phase motors and their remarks are applical to that. What he said was (cut and pasted from the original article): ================================================== ==================== I'm having a Leeson VFD (Model #174273, leeson.com) installed on a lathe by the seller. It has 220v sgl phase in. I purchased the VFD separately. ================================================== ==================== If the "It has 220v single phase in." applies to the lathe, then yes, he has the problem which you have spotted. Agreed that a single-phase motor will not work with the output of a VFD unless it is kept at 60 Hz. The real question is whether that was supposed to apply to the motor (and lathe), or the VFD. I assumed that it applied to the VFD, as did most of the rest of us. Careful sentence construction is more the exception than the rule here, I fear, so we'll have to see. If the motor is a single-phase one, then why did he buy a VFD in the first place? Enjoy, DoN. -- Email: | Voice (all times): (703) 938-4564 (too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html --- Black Holes are where God is dividing by zero --- |
#19
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VFD won't work on lathe, Why?
Koz wrote in message ...
snipped... Someone said here that a two speed motor would NOT work with a VFD. Not being all that good with motor electrics, I was wondering why this was. I was under the impression that 2 speed 3 phase motors simply energised the poles in the motor differently to achieve the second speed. My lathe has a 5 HP 2 speed and it would be nice to run it off the VFD simply because my current rotary convertor won't run it well on the low range (hates to start). It would be very difficult to change out the motor in this one and I don't have time to monkey around with it anyway. Koz Charles A. Sherwood wrote: -- I have an inverter driving a two speed motor. Works GREAT! From .5 to 180 Hz. What could possibly be the problem? Pete |
#20
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VFD won't work on lathe, Why?
The VFD is single phase in, 3 phase out. The motor
is 3 phase. To my knowledge the motor is a single speed. I passed on the suggestions that I picked up from you guys. I also learned a few things that I didn't know. They are interested in selling the VFD as an option. I'm the prototype customer because I wanted the VFD. (See what happens when you read the newsgroup and everyone likes the VFD's!) After they explained the problems to me, they 1st offered to return my check and my VFD. Good guys. I let them know I'll buy the lathe even if the VFD doesn't work out. An expert from Leeson and an expert from the lathe place were supposed to get together today to discuss it. I didn't hear back yet, so it probably didn't happen today as planned. I'm just going to wait until they figure out what is going on. I'll post back when they respond. Thanks all! |
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